The Variation of Animals and Plants under Domestication
by
Charles Darwin
Part 9 out of 10
produced this white moss-rose, two weak shoots were thrown up, and buds
from these yielded the beautiful striped moss-rose. The common moss-rose
has yielded by bud-variation, besides the old single red moss-rose, the old
scarlet semi-double moss-rose, and the sage-leaf moss-rose, which "has a
delicate shell-like form, and is of a beautiful blush colour; it is now
(1852) nearly extinct." (11/42. All these statements on the origin of the
several varieties of the moss-rose are given on the authority of Mr.
Shailer, who, together with his father, was concerned in their original
propagation. See 'Gard. Chronicle' 1852 page 759.) A white moss-rose has
been seen to bear a flower half white and half pink. (11/43. 'Gardener's
Chronicle' 1845 page 564.) Although several moss-roses have thus certainly
arisen by bud-variation, the greater number probably owe their origin to
seed of moss-roses. For Mr. Rivers informs me that his seedlings from the
old single moss-rose almost always produced moss-roses; and the old single
moss-rose was, as we have seen, the product by bud-variation of the double
moss-rose originally imported from Italy. That the original moss-rose was
the product of bud-variation is probable, from the facts above given and
from the de Meaux moss-rose (also a variety of R. centifolia) (11/44.
'Transact. Hort. Soc.' volume 2 page 242.) having appeared as a sporting
branch on the common rose de Meaux. Prof. Caspary has carefully described
(11/45. 'Shriften der Phys. Oekon. Gesell. zu Konigsberg' February 3, 1865
s. 4. See also Dr. Caspary's paper in 'Transactions of the Hort. Congress
of Amsterdam' 1865.) the case of a six-year-old white moss-rose, which sent
up several suckers, one of which was thorny, and produced red flowers,
destitute of moss, exactly like those of the Provence rose (R. centifolia):
another shoot bore both kinds of flowers, and in addition longitudinally
striped flowers. As this white moss-rose had been grafted on the Provence
rose, Prof. Caspary attributes the above changes to the influence of the
stock; but from the facts already given, and from others to be given, bud-
variation, with reversion, is probably a sufficient explanation.
Many other instances could be added of roses varying by buds. The white
Provence rose apparently originated in this way. (11/46. 'Gardener's
Chronicle' 1852 page 759.) M. Carriere states (page 36) that he himself
knows of five varieties thus produced by the Baronne Prevost. The double
and highly-coloured Belladonna rose has produced by suckers both semi-
double and almost single white roses (11/47. 'Transact. Hort. Soc.' volume
2 page 242.); whilst suckers from one of these semi-double white roses
reverted to perfectly characterised Belladonnas. In St. Domingo, varieties
of the China rose propagated by cuttings often revert after a year or two
into the old China rose. (11/48. Sir R. Schomburgk 'Proc. Linn. Soc. Bot.'
volume 2 page 132.) Many cases have been recorded of roses suddenly
becoming striped or changing their character by segments: some plants of
the Comtesse de Chabrillant, which is properly rose-coloured, were
exhibited in 1862 (11/49. 'Gardener's Chronicle' 1862 page 619.), with
crimson flakes on a rose ground. I have seen the Beauty of Billiard with a
quarter and with half the flower almost white. 'The Austrian bramble (R.
lutea) not rarely (11/50. Hopkirk 'Flora Anomala' 167.) produces branches
with pure yellow flowers; and Prof. Henslow has seen exactly half the
flower of a pure yellow, and I have seen narrow yellow streaks on a single
petal, of which the rest was of the usual copper colour.
The following cases are highly remarkable. Mr. Rivers, as I am informed by
him, possessed a new French rose with delicate smooth shoots, pale
glaucous-green leaves, and semi-double pale flesh-coloured flowers striped
with dark red; and on branches thus characterised there suddenly appeared
in more than one instance, the famous old rose called the Baronne Prevost,
with its stout thorny shoots, and immense, uniformly and richly coloured
double flowers; so that in this case the shoots, leaves, and flowers, all
at once changed their character by bud-variation. According to M. Verlot
(11/51. 'Sur La Production et la Fixation des Varietes' 1865 page 4.), a
variety called Rosa cannabifolia, which has peculiarly shaped leaflets, and
differs from every member of the family in the leaves being opposite
instead of alternate, suddenly appeared on a plant of R. alba in the
gardens of the Luxembourg. Lastly, "a running shoot" was observed by Mr. H.
Curtis (11/52. 'Journal of Horticulture' March 1865 page 233.) on the old
Aimee Vibert Noisette, and he budded it on Celine; thus a climbing Aimee
Vibert was first produced and afterwards propagated.
DIANTHUS.
It is quite common with the Sweet William (D. barbatus) to see differently
coloured flowers on the same root; and I have observed on the same truss
four differently coloured and shaded flowers. Carnations and pinks (D.
caryophyllus, etc.) occasionally vary by layers; and some kinds are so
little certain in character that they are called by floriculturists "catch-
flowers." (11/53. 'Gardener's Chronicle' 1843 page 135.) Mr. Dickson has
ably discussed the "running" of particoloured or striped carnations, and
says it cannot be accounted for by the compost in which they are grown:
"layers from the same clean flower would come part of them clean and part
foul, even when subjected to precisely the same treatment; and frequently
one flower alone appears influenced by the taint, the remainder coming
perfectly clean." (11/54. Ibid 1842 page 55.) This running of the parti-
coloured flowers apparently is a case of reversion by buds to the original
uniform tint of the species.
I will briefly mention some other cases of bud-variation to show how many
plants belonging to many orders have varied in their flowers; and many
others might be added. I have seen on a snap-dragon (Antirrhinum majus)
white, pink, and striped flowers on the same plant, and branches with
striped flowers on a red-coloured variety. On a double stock (Matthiola
incana) I have seen a branch bearing single flowers; and on a dingy-purple
double variety of the wall-flower (Cheiranthus cheiri), a branch which had
reverted to the ordinary copper colour. On other branches of the same
plant, some flowers were exactly divided across the middle, one half being
purple and the other coppery; but some of the smaller petals towards the
centre of these same flowers were purple longitudinally streaked with
coppery colour, or coppery streaked with purple. A Cyclamen (11/55.
'Gardener's Chronicle' 1867 page 235.) has been observed to bear white and
pink flowers of two forms, the one resembling the Persicum strain, and the
other the Coum strain. Oenothera biennis has been seen (11/56. Gartner
'Bastarderzeugung' s. 305.) bearing flowers of three different colours. The
hybrid Gladiolus colvilii occasionally bears uniformly coloured flowers,
and one case is recorded (11/57. Mr. D. Beaton in 'Cottage Gardener' 1860
page 250.) of all the flowers on a plant thus changing colour. A Fuchsia
has been seen (11/58. 'Gardener's Chronicle' 1850 page 536.) bearing two
kinds of flowers. Mirabilis jalapa is eminently sportive, sometimes bearing
on the same root pure red, yellow, and white flowers, and others striped
with various combinations of these three colours. (11/59. Braun 'Ray Soc.
Bot. Mem.' 1853 page 315; Hopkirk 'Flora Anomala' page 164; Lecoq
'Geograph. Bot. de l'Europe' tome 3 1854 page 405; and 'De la Fecondation'
1862 page 303.) The plants of the Mirabilis, which bear such
extraordinarily variable flowers in most, probably in all, cases, owe their
origin, as shown by Prof. Lecoq, to crosses between differently coloured
varieties.
LEAVES AND SHOOTS.
Changes, through bud-variation, in fruits and flowers have hitherto been
treated of; incidentally some remarkable modifications in the leaves and
shoots of the rose and Paritium, and in a lesser degree in the foliage of
the Pelargonium and Chrysanthemum, have been noticed. I will now add a few
more cases of variation in leaf-buds. Verlot (11/60. 'Des Varietes' 1865
page 5.) states that on Aralia trifoliata, which properly has leaves with
three leaflets, branches frequently appear bearing simple leaves of various
forms; these can be propagated by buds or by grafting, and have given rise,
as he states, to several nominal species.
With respect to trees, the history of but few of the many varieties with
curious or ornamental foliage is known; but several probably have
originated by bud-variation. Here is one case:--An old ash-tree (Fraxinus
excelsior) in the grounds of Necton, as Mr. Mason states, "for many years
has had one bough of a totally different character to the rest of the tree,
or of any other ash-tree which I have seen; being short-jointed and densely
covered with foliage." It was ascertained that this variety could be
propagated by grafts. (11/61. W. Mason in 'Gardener's Chronicle' 1843 page
878.) The varieties of some trees with cut leaves, as the oak-leaved
laburnum, the parsley-leaved vine, and especially the fern-leaved beech,
are apt to revert by buds to the common forms. (11/62. Alex. Braun 'Ray
Soc. Bot. Mem.' 1853 page 315; 'Gardener's Chron.' 1841 page 329.) The
fern-like leaves of the beech sometimes revert only partially, and the
branches display here and there sprouts bearing common leaves, fern-like,
and variously shaped leaves. Such cases differ but little from the so-
called heterophyllus varieties, in which the tree habitually bears leaves
of various forms; but it is probable that most heterophyllous trees have
originated as seedlings. There is a sub-variety of the weeping willow with
leaves rolled up into a spiral coil; and Mr. Masters states that a tree of
this kind kept true in his garden for twenty-five years, and then threw out
a single upright shoot bearing flat leaves. (11/63. Dr. M.T. Masters 'Royal
Institution Lecture' March 16, 1860.)
I have often noticed single twigs and branches on beech and other trees
with their leaves fully expanded before those on the other branches had
opened; and as there was nothing in their exposure or character to account
for this difference, I presume that they had appeared as bud-variations,
like the early and late fruit-maturing varieties of the peach and
nectarine.
Cryptogamic plants are liable to bud-variation, for fronds on the same fern
often display remarkable deviations of structure. Spores, which are of the
nature of buds, taken from such abnormal fronds, reproduce, with remarkable
fidelity, the same variety, after passing through the sexual stage. (11/64.
See Mr. W.K. Bridgeman's curious paper in 'Annals and Mag. of Nat. Hist.'
December 1861; also Mr. J. Scott 'Bot. Soc. Edinburgh' June 12, 1862.)
With respect to colour, leaves often become by bud-variation zoned,
blotched, or spotted with white, yellow, and red; and this occasionally
occurs even with plants in a state of nature. Variegation, however, appears
still more frequently in plants produced from seed; even the cotyledons or
seed-leaves being thus affected. (11/65. 'Journal of Horticulture' 1861
page 336; Verlot 'Des Varietes' page 76.) There have been endless disputes
whether variegation should be considered as a disease. In a future chapter
we shall see that it is much influenced, both in the case of seedlings and
of mature plants, by the nature of the soil. Plants which have become
variegated as seedlings, generally transmit their character by seed to a
large proportion of their progeny; and Mr. Salter has given me a list of
eight genera in which this occurred. (11/66. See also Verlot 'Des Varietes'
page 74.) Sir F. Pollock has given me more precise information: he sowed
seed from a variegated plant of Ballota nigra which was found growing wild,
and thirty per cent of the seedlings were variegated; seed from these
latter being sown, sixty per cent came up variegated. When branches become
variegated by bud-variation, and the variety is attempted to be propagated
by seed, the seedlings are rarely variegated: Mr. Salter found this to be
the case with plants belonging to eleven genera, in which the greater
number of the seedlings proved to be green-leaved; yet a few were slightly
variegated, or were quite white, but none were worth keeping. Variegated
plants, whether originally produced from seeds or buds, can generally be
propagated by budding, grafting, etc.; but all are apt to revert by bud-
variation to their ordinary foliage. This tendency, however, differs much
in the varieties of even the same species; for instance, the golden-striped
variety of Euonymus japonicus "is very liable to run back to the green-
leaved, while the silver-striped variety hardly ever changes." (11/67.
'Gardener's Chron.' 1844 page 86.) I have seen a variety of the holly, with
its leaves having a central yellow patch, which had everywhere partially
reverted to the ordinary foliage, so that on the same small branch there
were many twigs of both kinds. In the pelargonium, and in some other
plants, variegation is generally accompanied by some degree of dwarfing, as
is well exemplified in the "Dandy" pelargonium. When such dwarf varieties
sport back by buds or suckers to the ordinary foliage, the dwarfed stature
still remains. (11/68. Ibid 1861 page 963.) It is remarkable that plants
propagated from branches which have reverted from variegated to plain
leaves (11/69. Ibid 1861 page 433; 'Cottage Gardener' 1860 page 2.) do not
always (or never, as one observer asserts) perfectly resemble the original
plain-leaved plant from which the variegated branch arose: it seems that a
plant, in passing by bud-variation from plain leaves to variegated, and
back again from variegated to plain, is generally in some degree affected
so as to assume a slightly different aspect.
BUD-VARIATION BY SUCKERS, TUBERS, AND BULBS.
All the cases hitherto given of bud-variation in fruits, flowers, leaves,
and shoots, have been confined to buds on the stems or branches, with the
exception of a few cases incidentally noticed of varying suckers in the
rose, pelargonium, and chrysanthemum. I will now give a few instances of
variation in subterranean buds, that is, by suckers, tubers, and bulbs; not
that there is any essential difference between buds above and beneath the
ground. Mr. Salter informs me that two variegated varieties of Phlox
originated as suckers; but I should not have thought these worth
mentioning, had not Mr. Salter found, after repeated trials, that he could
not propagate them by "root-joints," whereas, the variegated Tussilago
farfara can thus be safely propagated (11/70. M. Lemoine quoted in
'Gardener's Chronicle' 1867 page 74 has lately observed that the Symphytum
with variegated leaves cannot be propagated by division of the roots. He
also found that out of 500 plants of a Phlox with striped flowers, which
had been propagated by root-division, only seven or eight produced striped
flowers. See also on striped Pelargoniums 'Gardener's Chronicle' 1867 page
1000.); but this latter plant may have originated as a variegated seedling,
which would account for its greater fixedness of character. The Barberry
(Berberis vulgaris) offers an analogous case; there is a well-known variety
with seedless fruit, which can be propagated by cuttings or layers; but
suckers always revert to the common form, which produces fruit containing
seeds. (11/71. Anderson 'Recreations in Agriculture' volume 5 page 152.) My
father repeatedly tried this experiment, and always with the same result. I
may here mention that maize and wheat sometimes produce new varieties from
the stock or root, as does the sugar-cane. (11/72. For wheat see
'Improvement of the Cereals' by P. Shirreff 1873 page 47. For maize and
sugar-cane Carriere ibid pages 40, 42. With respect to the sugar-cane Mr.
J. Caldwell of Mauritius says ('Gardener's Chronicle' 1874 page 316) the
Ribbon cane has here "sported into a perfectly green cane and a perfectly
red cane from the same head. I verified this myself, and saw at least 200
instances in the same plantation, and the fact has completely upset all our
preconceived ideas of the difference of colour being permanent. The
conversion of a striped cane into a green cane was not uncommon, but the
change into a red cane universally disbelieved, and that both events should
occur in the same plant incredible. I find, however, in Fleischman's
'Report on Sugar Cultivation in Louisiana for 1848 by the American Patent
Office, the circumstance is mentioned, but he says he never saw it
himself.")
Turning now to tubers: in the common Potato (Solanum tuberosum) a single
bud or eye sometimes varies and produces a new variety; or, occasionally,
and this is a much more remarkable circumstance, all the eyes in a tuber
vary in the same manner and at the same time, so that the whole tuber
assumes a new character. For instance, a single eye in a tuber of the old
FORTY-FOLD POTATO, which is a purple variety, was observed (11/73.
'Gardener's Chronicle' 1857 page 662.) to become white; this eye was cut
out and planted separately, and the kind has since been largely propagated.
KEMP'S POTATO is properly white, but a plant in Lancashire produced two
tubers which were red, and two which were white; the red kind was
propagated in the usual manner by eyes, and kept true to its new colour,
and, being found a more productive variety, soon became widely known under
the name of TAYLOR'S FORTY-FOLD. (11/74. 'Gard. Chronicle' 1841 page 814.)
The old FORTY-FOLD POTATO, as already stated, is a purple variety; but a
plant long cultivated on the same ground produced, not, as in the case
above given, a single white eye, but a whole white tuber, which has since
been propagated and keeps true. (11/75. Ibid 1857 page 613.) Several cases
have been recorded of large portions of whole rows of potatoes slightly
changing their character. (11/76. Ibid 1857 page 679. See also Philips
'Hist. of Vegetables' volume 2 page 91 for other and similar accounts.)
Dahlias propagated by tubers under the hot climate of St. Domingo vary
much; Sir R. Schomburgk gives the case of the "Butterfly variety," which
the second year produced on the same plant "double and single flowers; here
white petals edged with maroon; there of a uniform deep maroon." (11/77.
'Journal of Proc. Linn. Soc.' volume 2 Botany page 132.) Mr. Bree also
mentions a plant "which bore two different kinds of self-coloured flowers,
as well as a third kind which partook of both colours beautifully
intermixed." (11/78. Loudon's 'Gardener's Mag.' volume 8 1832 page 94.)
Another case is described of a dahlia with purple flowers which bore a
white flower streaked with purple. (11/79. 'Gard. Chronicle' 1850 page 536;
and 1842 page 729.)
Considering how long and extensively many Bulbous plants have been
cultivated, and how numerous are the varieties produced from seed, these
plants have not perhaps varied so much by offsets,--that is, by the
production of new bulbs,--as might have been expected. With the Hyacinth,
however, several instances have been given by M. Carriere. A case also has
been recorded of a blue variety which for three successive years gave
offsets producing white flowers with a red centre. (11/80. 'Des Jacinthes'
etc. Amsterdam 1768 page 122.) Another hyacinth bore (11/81. 'Gardener's
Chronicle' 1845 page 212.) on the same truss a perfectly pink and a
perfectly blue flower. I have seen a bulb producing at the same time one
stalk or truss with fine blue flowers, another with fine red flowers, and a
third with blue flowers on one side and red on the other; several of the
flowers being also longitudinally striped red and blue.
Mr. John Scott informs me that in 1862 Imatophyllum miniatum, in the
Botanic Gardens of Edinburgh, threw up a sucker which differed from the
normal form, in the leaves being two-ranked instead of four-ranked. The
leaves were also smaller, with the upper surface raised instead of being
channelled.
In the propagation of TULIPS, seedlings are raised, called selfs or
breeders, which, "consist of one plain colour on a white or yellow bottom.
These, being cultivated on a dry and rather poor soil, become broken or
variegated and produce new varieties. The time that elapses before they
break varies from one to twenty years or more, and sometimes this change
never takes place." (11/82. Loudon's 'Encyclopaedia of Gardening' page
1024.) The broken or variegated colours which give value to all tulips are
due to bud-variation; for although the Bybloemens and some other kinds have
been raised from several distinct breeders, yet all the Baguets are said to
have come from a single breeder or seedling. This bud-variation, in
accordance with the views of MM. Vilmorin and Verlot (11/83. 'Production
des Varietes' 1865 p. 63.) is probably an attempt to revert to that uniform
colour which is natural to the species. A tulip, however, which has already
become broken, when treated with too strong manure, is liable to flush or
lose by a second act of reversion its variegated colours. Some kinds, as
Imperatrix Florum, are much more liable than others to flushing; and Mr.
Dickson maintains (11/84. 'Gardener's Chronicle' 1841 page 782; 1842 page
55.) that this can no more be accounted for than the variation of any other
plant. He believes that English growers, from care in choosing seed from
broken flowers instead of from plain flowers, have to a certain extent
diminished the tendency in flowers already broken to flushing or secondary
reversion. Iris xiphium, according to M. Carriere (page 65), behaves in
nearly the same manner, as do so many tulips.
During two consecutive years all the early flowers in a bed of Tigridia
conchiflora (11/85. 'Gardener's Chron.' 1849 page 565.) resembled those of
the old T. pavonia; but the later flowers assumed their proper colour of
fine yellow, spotted with crimson. An apparently authentic account has been
published (11/86. 'Transact. Lin. Soc.' volume 2 page 354.) of two forms of
Hemerocallis, which have been universally considered as distinct species,
changing into each other; for the roots of the large-flowered tawny H.
fulva, being divided and planted in a different soil and place, produced
the small-flowered H. flava, as well as some intermediate forms. It is
doubtful whether such cases as these latter, as well as the "flushing" of
broken tulips and the "running" of particoloured carnations,--that is,
their more or less complete return to a uniform tint,--ought to be classed
under bud-variation, or ought to be retained for the chapter in which I
treat of the direct action of the conditions of life on organic beings.
These cases, however, have this much in bud-variation, that the change is
effected through buds and not through seminal reproduction. But, on the
other hand, there is this difference--that in ordinary cases of bud-
variation, one bud alone changes, whilst in the foregoing cases all the
buds on the same plant were modified together. With the potato, we have
seen an intermediate case, for all the eyes in one tuber simultaneously
changed their character.
I will conclude with a few allied cases, which may be ranked either under
bud-variation, or under the direct action of the conditions of life. When
the common Hepatica is transplanted from its native woods, the flowers
change colour, even during the first year. (11/87. Godron 'De l'Espece'
tome 2 page 84.) It is notorious that the improved varieties of the
Heartsease (Viola tricolor), when transplanted, often produce flowers
widely different in size, form, and colour: for instance, I transplanted a
large uniformly-coloured dark purple variety, whilst in full flower, and it
then produced much smaller, more elongated flowers, with the lower petals
yellow; these were succeeded by flowers marked with large purple spots, and
ultimately, towards the end of the same summer, by the original large dark
purple flowers. The slight changes which some fruit-trees undergo from
being grafted and regrafted on various stocks (11/88. M. Carriere has
lately described in the 'Revue Horticole' December 1, 1866 page 457, an
extraordinary case. He twice inserted grafts of the Aria vestita on thorn-
trees (epines) growing in pots; and the grafts, as they grew, produced
shoots with bark, buds, leaves, petioles, petals, and flower-stalks, all
widely different from those of the Aria. The grafted shoots were also much
hardier, and flowered earlier, than those on the ungrafted Aria.) were
considered by Andrew Knight (11/89. 'Transact. Hort. Soc.' volume 2 page
160.) as closely allied to "sporting branches," or bud-variations. Again,
we have the case of young fruit-trees changing their character as they grow
old; seedling pears, for instance, lose with age their spines and improve
in the flavour of their fruit. Weeping birch-trees, when grafted on the
common variety, do not acquire a perfect pendulous habit until they grow
old: on the other hand, I shall hereafter give the case of some weeping
ashes which slowly and gradually assumed an upright habit of growth. All
such changes, dependent on age, may be compared with the changes, alluded
to in the last chapter, which many trees naturally undergo; as in the case
of the Deodar and Cedar of Lebanon, which are unlike in youth, whilst they
closely resemble each other in old age; and as with certain oaks, and with
some varieties of the lime and hawthorn. (11/90. For the cases of oaks see
Alph. De Candolle in 'Bibl. Univers.' Geneva November 1862; for limes etc.
Loudon's 'Gard. Mag.' volume 11 1835 page 503.)]
GRAFT-HYBRIDS.
Before giving a summary on Bud-variation I will discuss some singular and
anomalous cases, which are more or less closely related to this same
subject. I will begin with the famous case of Adam's laburnum or Cytisus
adami, a form or hybrid intermediate between two very distinct species,
namely, C. laburnum and purpureus, the common and purple laburnum; but as
this tree has often been described, I will be as brief as I can.
[Throughout Europe, in different soils and under different climates,
branches on this tree have repeatedly and suddenly reverted to the two
parent species in their flowers and leaves. To behold mingled on the same
tree tufts of dingy-red, bright yellow, and purple flowers, borne on
branches having widely different leaves and manner of growth, is a
surprising sight. The same raceme sometimes bears two kinds of flowers; and
I have seen a single flower exactly divided into halves, one side being
bright yellow and the other purple; so that one half of the standard-petal
was yellow and of larger size, and the other half purple and smaller. In
another flower the whole corolla was bright yellow, but exactly half the
calyx was purple. In another, one of the dingy-red wing-petals had a narrow
bright yellow stripe on it; and lastly, in another flower, one of the
stamens, which had become slightly foliaceous, was half yellow and half
purple; so that the tendency to segregation of character or reversion
affects even single parts and organs. (11/91. For analogous facts see Braun
'Rejuvenescence' in 'Ray Soc. Bot. Mem.' 1853 page 320; and 'Gardener's
Chronicle' 1842 page 397; also Braun in 'Sitzungsberichte der Ges.
naturforschender Freunde' June 1873 page 63.) The most remarkable fact
about this tree is that in its intermediate state, even when growing near
both parent-species, it is quite sterile; but when the flowers become pure
yellow or pure purple they yield seed. I believe that the pods from the
yellow flowers yield a full complement of seed; they certainly yield a
larger number. Two seedlings raised by Mr. Herbert from such seed (11/92.
'Journal of Hort. Soc.' volume 2 1847 page 100.) exhibited a purple tinge
on the stalks of their flowers; but several seedlings raised by myself
resembled in every character the common laburnum, with the exception that
some of them had remarkably long racemes: these seedlings were perfectly
fertile. That such purity of character and fertility should be suddenly
reacquired from so hybridised and sterile a form is an astonishing
phenomenon. The branches with purple flowers appear at first sight exactly
to resemble those of C. purpureus; but on careful comparison I found that
they differed from the pure species in the shoots being thicker, the leaves
a little broader, and the flowers slightly shorter, with the corolla and
calyx less brightly purple: the basal part of the standard-petal also
plainly showed a trace of the yellow stain. So that the flowers, at least
in this instance, had not perfectly recovered their true character; and in
accordance with this, they were not perfectly fertile, for many of the pods
contained no seed, some produced one, and very few contained as many as two
seeds; whilst numerous pods on a tree of the pure C. purpureus in my garden
contained three, four, and five fine seeds. The pollen, moreover, was very
imperfect, a multitude of grains being small and shrivelled; and this is a
singular fact; for, as we shall immediately see, the pollen-grains in the
dingy-red and sterile flowers on the parent-tree, were, in external
appearance, in a much better state, and included very few shrivelled
grains. Although the pollen of the reverted purple flowers was in so poor a
condition, the ovules were well formed, and the seeds, when mature,
germinated freely with me. Mr. Herbert raised plants from seeds of the
reverted purple flowers, and they differed a VERY LITTLE from the usual
state of C. purpureus. Some which I raised in the same manner did not
differ at all, either in the character of their flowers or of the whole
bush, from the pure C. purpureus. Prof. Caspary has examined the ovules of
the dingy-red and sterile flowers in several plants of C. adami on the
Continent (11/93. See 'Transact. of Hort. Congress of Amsterdam' 1865; but
I owe most of the following information to Prof. Caspary's letters.) and
finds them generally monstrous. In three plants examined by me in England,
the ovules were likewise monstrous, the nucleus varying much in shape, and
projecting irregularly beyond the proper coats. The pollen grains, on the
other hand, judging from their external appearance, were remarkably good,
and readily protruded their tubes. By repeatedly counting, under the
microscope, the proportional number of bad grains, Prof. Caspary
ascertained that only 2.5 per cent were bad, which is a less proportion
than in the pollen of three pure species of Cytisus in their cultivated
state, viz., C. purpureus, laburnum, and alpinus. Although the pollen of C.
adami is thus in appearance good, it does not follow, according to M.
Naudin's observation (11/94. 'Nouvelles Archives du Museum' tome 1 page
143.) on Mirabilis, that it would be functionally effective. The fact of
the ovules of C. adami being monstrous, and the pollen apparently sound, is
all the more remarkable, because it is opposed to what usually occurs not
only with most hybrids (11/95. See on this head Naudin ibid page 141.), but
with two hybrids in the same genus, namely in C. purpureo-elongatus, and C.
alpino-laburnum. In both these hybrids, the ovules, as observed by Prof.
Caspary and myself, were well-formed, whilst many of the pollen-grains were
ill-formed; in the latter hybrid 20.3 per cent, and in the former no less
than 84.8 per cent of the grains were ascertained by Prof. Caspary to be
bad. This unusual condition of the male and female reproductive elements in
C. adami has been used by Prof. Caspary as an argument against this plant
being considered as an ordinary hybrid produced from seed; but we should
remember that with hybrids the ovules have not been examined nearly so
frequently as the pollen, and they may be much oftener imperfect than is
generally supposed. Dr. E. Bornet, of Antibes, informs me (through Mr. J.
Traherne Moggridge) that with hybrid Cisti the ovarium is frequently
deformed, the ovules being in some cases quite absent, and in other cases
incapable of fertilisation.
Several theories have been propounded to account for the origin of C.
adami, and for the transformations which it undergoes. The whole case has
been attributed by some authors to bud-variation; but considering the wide
difference between C. laburnum and purpureus, both of which are natural
species, and considering the sterility of the intermediate form, this view
may be summarily rejected. We shall presently see that, with hybrid plants,
two embryos differing in their characters may be developed within the same
seed and cohere; and it has been supposed that C. adami thus originated.
Many botanists maintain that C. adami is a hybrid produced in the common
way by seed, and that it has reverted by buds to its two parent-forms.
Negative results are not of much value; but Reisseck, Caspary, and myself,
tried in vain to cross C. laburnum and purpureus; when I fertilised the
former with pollen of the latter, I had the nearest approach to success,
for pods were formed, but in sixteen days after the withering of the
flowers, they fell off. Nevertheless, the belief that C. adami is a
spontaneously produced hybrid between these two species is supported by the
fact that such hybrids have arisen in this genus. In a bed of seedlings
from C. elongatus, which grew near to C. purpureus, and was probably
fertilised by it through the agency of insects (for these, as I know by
experiment, play an important part in the fertilisation of the laburnum),
the sterile hybrid C. purpureo-elongatus appeared. (11/96. Braun in 'Bot.
Mem. Ray. Soc.' 1853 page 23.) Thus, also, Waterer's laburnum, the C.
alpino-laburnum (11/97. This hybrid has never been described. It is exactly
intermediate in foliage, time of flowering, dark striae at the base of the
standard petal, hairiness of the ovarium, and in almost every other
character, between C. laburnum and alpinus; but it approaches the former
species more nearly in colour, and exceeds it in the length of the racemes.
We have before seen that 20.3 per cent of its pollen-grains are ill-formed
and worthless. My plant, though growing not above thirty or forty yards
from both parent-species, during some seasons yielded no good seeds; but in
1866 it was unusually fertile, and its long racemes produced from one to
occasionally even four pods. Many of the pods contained no good seeds, but
generally they contained a single apparently good seed, sometimes two, and
in one case three seeds. Some of these seeds germinated, and I raised two
trees from them; one resembles the present form; the other has a remarkable
dwarf character with small leaves, but has not yet flowered.) spontaneously
appeared, as I am informed by Mr. Waterer, in a bed of seedlings.
On the other hand, we have a clear and distinct account given to Poiteau
(11/98. 'Annales de la Soc. de l'Hort. de Paris' tome 7 1830 page 93.) by
M. Adam, who raised the plant, showing that C. adami is not an ordinary
hybrid; but is what may be called a graft-hybrid, that is, one produced
from the united cellular tissue of two distinct species. M. Adam inserted
in the usual manner a shield of the bark of C. purpureus into a stock of C.
laburnum; and the bud lay dormant, as often happens, for a year; the shield
then produced many buds and shoots, one of which grew more upright and
vigorous with larger leaves than the shoots of C. purpureus, and was
consequently propagated. Now it deserves especial notice that these plants
were sold by M. Adam, as a variety of C. purpureus, before they had
flowered; and the account was published by Poiteau after the plants had
flowered, but before they had exhibited their remarkable tendency to revert
into the two parent species. So that there was no conceivable motive for
falsification, and it is difficult to see how there could have been any
error. (11/99. An account was given in the 'Gardener's Chronicle' 1857
pages 382, 400, of a common laburnum on which grafts of C. purpureus had
been inserted, and which gradually assumed the character of C. adami; but I
have little doubt that C. adami had been sold to the purchaser, who was not
a botanist, in the place of C. purpureus. I have ascertained that this
occurred in another instance.) If we admit as true M. Adam's account, we
must admit the extraordinary fact that two distinct species can unite by
their cellular tissue, and subsequently produce a plant bearing leaves and
sterile flowers intermediate in character between the scion and stock, and
producing buds liable to reversion; in short, resembling in every important
respect a hybrid formed in the ordinary way by seminal reproduction.]
I will therefore give all the facts which I have been able to collect on
the formation of hybrids between distinct species or varieties, without the
intervention of the sexual organs. For if, as I am now convinced, this is
possible, it is a most important fact, which will sooner or later change
the views held by physiologists with respect to sexual reproduction. A
sufficient body of facts will afterwards be adduced, showing that the
segregation or separation of the characters of the two parent-forms by bud-
variation, as in the case of Cytisus adami, is not an unusual though a
striking phenomenon. We shall further see that a whole bud may thus revert,
or only half, or some smaller segment.
[The famous bizzarria Orange offers a strictly parallel case to that of
Cytisus adami. The gardener who in 1644 in Florence raised this tree,
declared that it was a seedling which had been grafted; and after the graft
had perished, the stock sprouted and produced the bizzarria. Gallesio, who
carefully examined several living specimens and compared them with the
description given by the original describer, P. Nato (11/100. Gallesio 'Gli
Agrumi dei Giard. Bot. Agrar. di. Firenze' 1839 page 11. In his 'Traite du
Citrus' 1811 page 146, he speaks as if the compound fruit consisted in part
of a lemon, but this apparently was a mistake.), states that the tree
produces at the same time leaves, flowers, and fruit identical with the
bitter orange and with the citron of Florence, and likewise compound fruit,
with the two kinds either blended together, both externally and internally,
or segregated in various ways. This tree can be propagated by cuttings, and
retains its diversified character. The so-called trifacial orange of
Alexandria and Smyrna (11/101. 'Gardener's Chron.' 1855 page 628. See also
Prof. Caspary in 'Transact. Hort. Congress of Amsterdam' 1865.) resembles
in its general nature the bizzarria, and differs only in the orange being
of the sweet kind; this and the citron are blended together in the same
fruit, or are separately produced on the same tree; nothing is known of its
origin. In regard to the bizzarria, many authors believe that it is a
graft-hybrid; Gallesio, on the other hand, thinks that it is an ordinary
hybrid, with the habit of partially reverting by buds to the two parent-
forms; and we have seen that the species in this genus often cross
spontaneously.
It is notorious that when the variegated Jessamine is budded on the common
kind, the stock sometimes produces buds bearing variegated leaves: Mr.
Rivers, as he informs me, has seen instances of this. The same thing occurs
with the Oleander. (11/102. Gartner 'Bastarderzeugung' s. 611 gives many
references on this subject.) Mr. Rivers, on the authority of a trustworthy
friend, states that some buds of a golden-variegated ash, which were
inserted into common ashes, all died except one; but the ash-stocks were
affected (11/103. A nearly similar account was given by Brabley in 1724 in
his 'Treatise on Husbandry' volume 1 page 199.) and produced, both above
and below the points of insertion of the plates of bark bearing the dead
buds, shoots which bore variegated leaves. Mr. J. Anderson Henry has
communicated to me a nearly similar case: Mr. Brown, of Perth, observed
many years ago, in a Highland glen, an ash-tree with yellow leaves; and
buds taken from this tree were inserted into common ashes, which in
consequence were affected, and produced the Blotched Breadalbane Ash. This
variety has been propagated, and has preserved its character during the
last fifty years. Weeping ashes, also, were budded on the affected stocks,
and became similarly variegated. It has been repeatedly proved that several
species of Abutilon, on which the variegated A. thompsonii has been
grafted, become variegated. (11/104. Morren 'Bull. de l'Acad. R. des
Sciences de Belgique' 2de series tome 28 1869 page 434. Also Magnus
'Gesellschaft naturforschender Freunde, Berlin' February 21, 1871 page 13;
ibid June 21, 1870 and October 17, 1871. Also 'Bot. Zeitung' February 24,
1871.)
Many authors consider variegation as the result of disease; and the
foregoing cases may be looked at as the direct result of the inoculation of
a disease or some weakness. This has been almost proved to be the case by
Morren in the excellent paper just referred to, who shows that even a leaf
inserted by its footstalk into the bark of the stock is sufficient to
communicate variegation to it, though the leaf soon perishes. Even fully
formed leaves on the stock of Abutilon are sometimes affected by the graft
and become variegated. Variegation is much influenced, as we shall
hereafter see, by the nature of the soil in which the plants are grown; and
it does not seem improbable that whatever change in the sap or tissues
certain soils induce, whether or not called a disease, might spread from
the inserted piece of bark to the stock. But a change of this kind cannot
be considered to be of the nature of a graft-hybrid.
There is a variety of the hazel with dark-purple leaves, like those of the
copper-beech: no one has attributed this colour to disease, and it
apparently is only an exaggeration of a tint which may often be seen on the
leaves of the common hazel. When this variety is grafted on the common
hazel (11/105. Loudon's 'Arboretum' volume 4 page 2595.), it sometimes
colours, as has been asserted, the leaves below the graft; although
negative evidence is not of much value, I may add that Mr. Rivers, who has
possessed hundreds of such grafted trees, has never seen an instance.
Gartner (11/106. 'Bastarderzeugung' s. 619.) quotes two separate accounts
of branches of dark and white-fruited vines which had been united in
various ways, such as being split longitudinally, and then joined, etc.;
and these branches produced distinct bunches of grapes of the two colours,
and other bunches with berries, either striped, or of an intermediate and
new tint. Even the leaves in one case were variegated. These facts are the
more remarkable because Andrew Knight never succeeded in raising variegated
grapes by fertilising white kinds by pollen of dark kinds; though, as we
have seen, he obtained seedlings with variegated fruits and leaves, by
fertilising a white variety by the already variegated dark Aleppo grape.
Gartner attributes the above-quoted cases merely to bud-variation; but it
is a strange coincidence that the branches which had been grafted in a
peculiar manner should alone thus have varied; and H. Adorne de Tscharner
positively asserts that he produced the described result more than once,
and could do so at will, by splitting and uniting the branches in the
manner described by him.
I should not have quoted the following case had not the author of 'Des
Jacinthes' (11/107. Amsterdam 1768 page 124.) impressed me with the belief
not only of his extensive knowledge, but of his truthfulness: he says that
bulbs of blue and red hyacinths may be cut in two, and that they will grow
together and throw up a united stem (and this I have myself seen) with
flowers of the two colours on the opposite sides. But the remarkable point
is, that flowers are sometimes produced with the two colours blended
together, which makes the case closely analogous with that of the blended
colours of the grapes on the united vine branches.
In the case of roses it is supposed that several graft-hybrids have been
formed, but there is much doubt about these cases, owing to the frequency
of ordinary bud-variations. The most trustworthy instance known to me is
one, recorded by Mr. Poynter (11/108. 'Gardener's Chron.' 1860 page 672
with a woodcut.) who assures me in a letter of the entire accuracy of the
statement. Rosa devoniensis had been budded some years previously on a
white Banksian rose; and from the much enlarged point of junction, whence
the Devoniensis and Banksian still continued to grow, a third branch
issued, which was neither pure Banksian nor pure Devoniensis, but partook
of the character of both; the flowers resembled, but were superior in
character to those of the variety called Lamarque (one of the Noisettes),
while the shoots were similar in their manner of growth to those of the
Banksian rose, with the exception that the longer and more robust shoots
were furnished with prickles. This rose was exhibited before the Floral
Committee of the Horticultural Society of London. Dr. Lindley examined it
and concluded that it had certainly been produced by the mingling of R.
banksiae with some rose like R. devoniensis, "for while it was very greatly
increased in vigour and in size of all the parts, the leaves were half-way
between a Banksian and Tea-scented rose." It appears that rose-growers were
previously aware that the Banksian rose sometimes affects other roses. As
Mr. Poynter's new variety is intermediate in its fruit and foliage between
the stock and scion, and as it arose from the point of junction between the
two, it is very improbable that it owes its origin to mere bud-variation,
independently of the mutual influence of the stock and scion.
Lastly, with respect to potatoes. Mr. R. Trail stated in 1867 before the
Botanical Society of Edinburgh (and has since given me fuller information),
that several years ago he cut about sixty blue and white potatoes into
halves through the eyes or buds, and then carefully joined them, destroying
at the same time the other eyes. Some of these united tubers produced
white, and others blue tubers; some, however, produced tubers partly white
and partly blue; and the tubers from about four or five were regularly
mottled with the two colours. In these latter cases we may conclude that a
stem had been formed by the union of the bisected buds, that is, by graft-
hybridisation.
In the 'Botanische Zeitung' (May 16, 1868), Professor Hildebrand gives an
account with a coloured figure, of his experiments on two varieties which
were found during the same season to be constant in character, namely, a
somewhat elongated rough-skinned red potato and a rounded smooth white one.
He inserted buds reciprocally into both kinds, destroying the other buds.
He thus raised two plants, and each of these produced a tuber intermediate
in character between the two parent-forms. That from the red bud grafted
into the white tuber, was at one end red and rough, as the whole tuber
ought to have been if not affected; in the middle it was smooth with red
stripes, and at the other end smooth and altogether white like that of the
stock.
Mr. Taylor, who had received several accounts of potatoes having been
grafted by wedge-shaped pieces of one variety inserted into another, though
sceptical on the subject, made twenty-four experiments which he described
in detail before the Horticultural Society. (11/109. 'Gardener's Chronicle'
1869 page 220.) He thus raised many new varieties, some like the graft or
like the stock; others having an intermediate character. Several persons
witnessed the digging up of the tubers from these graft-hybrids; and one of
them, Mr. Jameson, a large dealer in potatoes, writes thus, "They were such
a mixed lot, as I have never before or since seen. They were of all colours
and shapes, some very ugly and some very handsome." Another witness says
"some were round, some kidney, pink-eyed kidney, piebald, and mottled red
and purple, of all shapes and sizes." Some of these varieties have been
found valuable, and have been extensively propagated. Mr. Jameson took away
a large piebald potato which he cut into five sets and propagated; these
yielded round, white, red, and piebald potatoes.
Mr. Fitzpatrick followed a different plan (11/110. 'Gard. Chronicle' 1869
page 335.); he grafted together not the tubers but the young stems of
varieties producing black, white, and red potatoes. The tubers borne by
three of these twin or united plants were coloured in an extraordinary
manner; one was almost exactly half black and half white, so that some
persons on seeing it thought that two potatoes had been divided and
rejoined; other tubers were half red and half white, or curiously mottled
with red and white, or with red and black, according to the colours of the
graft and stock.
The testimony of Mr. Fenn is of much value, as he is "a well known potato-
grower" who has raised many new varieties by crossing different kinds in
the ordinary manner. He considers it "demonstrated" that new, intermediate
varieties can be produced by grafting the tubers, though he doubts whether
such will prove valuable. (11/111. 'Gardener's Chronicle' 1869 page 1018
with remarks by Dr. Masters on the adhesion of the united wedges. See also
ibid 1870 pages 1277, 1283.) He made many trials and laid the results,
exhibiting specimens, before the Horticultural Society. Not only were the
tubers affected, some being smooth and white at one end and rough and red
at the other, but the stems and leaves were modified in their manner of
growth, colour and precocity. Some of these graft-hybrids after being
propagated for three years still showed in their haulms their new
character, different from that of the kind from which the eyes had been
taken. Mr. Fenn gave twelve of the tubers of the third generation to Mr.
Alex. Dean, who grew them, and was thus converted into a believer in graft-
hybridisation, having previously been a complete sceptic. For comparison he
planted the pure parent-forms alongside the twelve tubers; and found that
many of the plants from the latter (11/112. 'Gard. Chronicle' 1871 page
837.) were intermediate between the two parent-forms in precocity, in the
tallness, uprightness, jointing, and robustness of the stems, and in the
size and colour of the leaves.
Another experimentalist, Mr. Rintoul, grafted no less than fifty-nine
tubers, which differed in shape (some being kidneys) in smoothness and
colour (11/113. 'Gardener's Chronicle' 1870 page 1506.) and many of the
plants thus raised "were intermediate in the tubers as well as in the
haulms." He describes the more striking cases.
In 1871 I received a letter from Mr. Merrick, of Boston, U.S.A., who states
that, "Mr. Fearing Burr, a very careful experimenter and author of a much
valued book, 'The Garden Vegetables of America' has succeeded in producing
distinctly mottled and most curious potatoes--evidently graft-hybrids, by
inserting eyes from blue or red potatoes into the substance of white ones,
after removing the eyes of the latter. I have seen the potatoes, and they
are very curious."
We will now turn to the experiments made in Germany, since the publication
of Prof. Hildebrand's paper. Herr Magnus relates (11/114. 'Sitzungsberichte
der Gesellschaft naturforschender Freunde zu Berlin' October 17, 1871.) the
results of numerous trials made by Herren Reuter and Lindemuth, both
attached to the Royal Gardens of Berlin. They inserted the eyes of red
potatoes into white ones, and vice versa. Many different forms partaking of
the characters of the inserted bud and of the stock were thus obtained; for
instance, some of the tubers were white with red eyes.
Herr Magnus also exhibited in the following year before the same Society
(November 19, 1872), the produce of grafts between black, white, and red
potatoes, made by Dr. Neubert. These were made by uniting not the tubers
but the young stems, as was done by Mr. Fitzpatrick. The result was
remarkable, inasmuch as all the tubers thus produced were intermediate in
character, though in a variable degree. Those between the black and the
white or the red were the most striking in appearance. Some from between
the white and red had one half of one colour and the other half of the
other colour.
At the next meeting of the society Herr Magnus communicated the results of
Dr. Heimann's experiments in grafting together the tubers of red Saxon,
blue, and elongated white potatoes. The eyes were removed by a cylindrical
instrument, and inserted into corresponding holes in other varieties. The
plants thus produced yielded a great number of tubers, which were
intermediate between the two parent-forms in shape, and in the colour both
of the flesh and skin.
Herr Reuter experimented (11/115. Ibid November 17, 1874. See also
excellent remarks by Herr Magnus.) by inserting wedges of the elongated
White Mexican potato into a Black Kidney potato. Both sorts are known to be
very constant, and differ much not only in form and colour, but in the eyes
of the Black Kidney being deeply sunk, whereas those of the White Mexican
are superficial and of a different shape. The tubers produced by these
hybrids were intermediate in colour and form; and some which resembled in
form the graft, i.e. the Mexican, had eyes deeply sunk and of the same
shape as in the stock or Black Kidney.]
Any one who will attentively consider the abstract now given, of the
experiments made by many observers in several countries, will, I think, be
convinced that by grafting two varieties of the potato together in various
ways, hybridised plants can be produced. It should be observed that several
of the experimentalists are scientific horticulturists, and some of them
potato-growers on a large scale, who, though beforehand sceptical, have
been fully convinced of the possibility, even of the ease, of making graft-
hybrids. The only way of escaping from this conclusion is to attribute all
the many recorded cases to simple bud-variation. Undoubtedly the potato, as
we have seen in this chapter, does sometimes, though not often, vary by
buds; but it should be especially noted that it is experienced potato-
growers, whose business it is to look out for new varieties, who have
expressed unbounded astonishment at the number of new forms produced by
graft-hybridisation. It may be argued that it is merely the operation of
grafting, and not the union of two kinds, which causes so extraordinary an
amount of bud-variation; but this objection is at once answered by the fact
that potatoes are habitually propagated by the tubers being cut into
pieces, and the sole difference in the case of graft-hybrids is that either
a half or a smaller segment or a cylinder is placed in close opposition
with the tissue of another variety. Moreover, in two cases, the young stems
were grafted together, and the plants thus united yielded the same results
as when the tubers were united. It is an argument of the greatest weight
that when varieties are produced by simple bud-variation, they frequently
present quite new characters; whereas in all the numerous cases above
given, as Herr Magnus likewise insists, the graft-hybrids are intermediate
in character between the two forms employed. That such a result should
follow if the one kind did not affect the other is incredible.
Characters of all kinds are affected by graft hybridisation, in whatever
way the grafting may have been effected. The plants thus raised yield
tubers which partake of the widely different colours, form, state of
surface, position and shape of the eye of the parents; and according to two
careful observers they are also intermediate in certain constitutional
peculiarities. But we should bear in mind that in all the varieties of the
potato, the tubers differ much more than any other part.
The potato affords the best evidence of the possibility of the formation of
graft-hybrids, but we must not overlook the account given of the origin of
the famous Cytisus adami by M. Adam, who had no conceivable motive for
deception, and the exactly parallel account of the origin of the Bizzarria
orange, namely by graft-hybridisation. Nor must the cases be undervalued in
which different varieties or species of vines, hyacinths and roses, have
been grafted together, and have yielded intermediate forms. It is evident
that graft-hybrids can be made much more easily with some plants, as the
potato, than with others, for instance our common fruit trees; for these
latter have been grafted by the million during many centuries, and though
the graft is often slightly affected, it is very doubtful whether this may
not be accounted for, merely by a more or less free supply of nutriment.
Nevertheless, the cases above given seem to me to prove that under certain
unknown conditions graft-hybridisation can be effected.
Herr Magnus asserts with much truth that graft-hybrids resemble in all
respects seminal hybrids, including their great diversity of character.
There is, however, a partial exception, inasmuch as the characters of the
two parent forms are not often homogeneously blended together in graft-
hybrids. They much more commonly appear in a segregated condition,--that
is, in segments either at first, or subsequently through reversion. It
would seem that the reproductive elements are not so completely blended by
grafting as by sexual generation. But segregation of this kind occurs by no
means rarely, as will be immediately shown, in seminal hybrids. Finally it
must, I think, be admitted that we learn from the foregoing cases a highly
important physiological fact, namely, that the elements that go to the
production of a new being, are not necessarily formed by the male and
female organs. They are present in the cellular tissue in such a state that
they can unite without the aid of the sexual organs, and thus give rise to
a new bud partaking of the characters of the two parent-forms.
ON THE SEGREGATION OF THE PARENTAL CHARACTERS IN SEMINAL HYBRIDS BY BUD-
VARIATION.
I will now give a sufficient number of cases to show that segregation of
this kind, namely, by buds, may occur in ordinary hybrids raised from seed.
[Hybrids were raised by Gartner between Tropaeolum minus and majus (11/116.
'Bastarderzeugung' s. 549. It is, however, doubtful whether these plants
should be ranked as species or varieties.) which at first produced flowers
intermediate in size, colour, and structure between their two parents; but
later in the season some of these plants produced flowers in all respects
like those of the mother-form, mingled with flowers still retaining the
usual intermediate condition. A hybrid Cereus between C. speciosissimus and
phyllanthus (11/117. Gartner ibid s. 550.) plants which are widely
different in appearance, produced for the first three years angular, five-
sided stems, and then some flat stems like those of C. phyllanthus.
Kolreuter also gives cases of hybrid Lobelias and Verbascums, which at
first produced flowers of one colour, and later in the season, flowers of a
different colour. (11/118. 'Journal de Physique' tome 23 1873 page 100.
'Act. Acad. St. Petersburgh' 1781 part 1 page 249.) Naudin (11/119.
'Nouvelles Archives du Museum' tome 1 page 49.) raised forty hybrids from
Datura laevis fertilised by D. stramonium; and three of these hybrids
produced many capsules, of which a half, or quarter, or lesser segment was
smooth and of small size, like the capsule of the pure D. laevis, the
remaining part being spinose and of larger size, like the capsule of the
pure D. stramonium: from one of these composite capsules, plants perfectly
resembling both parent-forms were raised.
Turning now to varieties. A SEEDLING apple, conjectured to be of crossed
parentage, has been described in France (11/120. L'Hermes January 14, 1837
quoted in Loudon's 'Gardener's Mag.' volume 13 page 230.) which bears fruit
with one half larger than the other, of a red colour, acid taste, and
peculiar odour; the other side being greenish-yellow and very sweet: it is
said scarcely ever to include perfectly developed seed. I suppose that this
is not the same tree as that which Gaudichaud (11/121. 'Comptes Rendus'
tome 34 1852 page 746.) exhibited before the French institute, bearing on
the same branch two distinct kinds of apples, one a reinette rouge, and the
other like a reinette canada jaunatre: this double-bearing variety can be
propagated by grafts, and continues to produce both kinds; its origin is
unknown. The Rev. J.D. La Touche sent me a coloured drawing of an apple
which he brought from Canada, of which half, surrounding and including the
whole of the calyx and the insertion of the foot-stalk, is green, the other
half being brown and of the nature of the pomme gris apple, with the line
of separation between the two halves exactly defined. The tree was a
grafted one, and Mr. La Touche thinks that the branches which bore this
curious apple sprung from the point of junction of the graft and stock: had
this fact been ascertained, the case would probably have come into the
class of graft-hybrids already given. But the branch may have sprung from
the stock, which no doubt was a seedling.
Prof. H. Lecoq, who has made a great number of crossings between the
differently coloured varieties of Mirabilis jalapa (11/122. 'Geograph. Bot.
de l'Europe' tome 3 1854 page 405; and 'De la Fecondation' 1862 page 302.)
finds that in the seedlings the colours rarely combine, but form distinct
stripes; or half the flower is of one colour and half of a different
colour. Some varieties regularly bear flowers striped with yellow, white,
and red; but plants of such varieties occasionally produce on the same root
branches with uniformly coloured flowers of all three tints, and other
branches with half-and-half coloured flowers, and others with marbled
flowers. Gallesio (11/123. 'Traite du Citrus' 1811 page 45.) crossed
reciprocally white and red carnations, and the seedlings were striped; but
some of the striped plants also bore entirely white and entirely red
flowers. Some of these plants produced one year red flowers alone, and in
the following year striped flowers; or conversely, some plants, after
having borne for two or three years striped flowers, would revert and bear
exclusively red flowers. It may be worth mentioning that I fertilised the
PURPLE SWEET-PEA (Lathyrus odoratus) with pollen from the light-coloured
PAINTED LADY: seedlings raised from the same pod were not intermediate in
character, but perfectly resembled either parent. Later in the summer, the
plants which had at first borne flowers identical with those of the PAINTED
LADY, produced flowers streaked and blotched with purple; showing in these
darker marks a tendency to reversion to the mother-variety. Andrew Knight
(11/124. 'Transact. Linn. Soc.' volume 9 page 268.) fertilised two white
grapes with pollen of the Aleppo grape, which is darkly variegated both in
its leaves and fruit. The result was that the young seedlings were not at
first variegated, but all became variegated during the succeeding summer;
besides this, many produced on the same plant bunches of grapes which were
all black, or all white, or lead-coloured striped with white, or white
dotted with minute black stripes; and grapes of all these shades could
frequently be found on the same foot-stalk.
I will append a very curious case, not of bud-variation, but of two
cohering embryos, different in character and contained within the same
seed. A distinguished botanist, Mr. G.H. Thwaites (11/125. 'Annals and Mag.
of Nat. Hist.' March 1848.) states that a seed from Fuchsia coccinea
fertilised by F. fulgens, contained two embryos, and was "a true vegetable
twin." The two plants produced from the two embryos were "extremely
different in appearance and character," though both resembled other hybrids
of the same parentage produced at the same time. These twin plants "were
closely coherent, below the two pairs of cotyledon-leaves, into a single
cylindrical stem, so that they had subsequently the appearance of being
branches on one trunk." Had the two united stems grown up to their full
height, instead of dying, a curiously mixed hybrid would have been
produced. A mongrel melon described by Sageret (11/126. 'Pomologie
Physiolog.' 1830 page 126.) may perhaps have thus originated; for the two
main branches, which arose from two cotyledon-buds, produced very different
fruit,--on the one branch like that of the paternal variety, and on the
other branch like to a certain extent that of the maternal variety, the
melon of China.]
In most of these cases of crossed varieties, and in some of the cases of
crossed species, the colours proper to both parents appeared in the
seedlings, as soon as they first flowered, in the form of stripes or larger
segments, or as whole flowers or fruit of different kinds borne on the same
plant; and in this case the appearance of the two colours cannot strictly
be said to be due to reversion, but to some incapacity of fusion. When,
however, the later flowers or fruit produced during the same season, or
during a succeeding year or generation, become striped or half-and-half,
etc., the segregation of the two colours is strictly a case of reversion by
bud-variation. Whether all the many recorded cases of striped flowers and
fruit are due to previous hybridisation and reversion is by no means clear,
for instance with peaches and nectarines, moss-roses, etc. In a future
chapter I shall show that, with animals of crossed parentage, the same
individual has been known to change its character during growth, and to
revert to one of its parents which it did not at first resemble. Finally,
from the various facts now given, there can be no doubt that the same
individual plant, whether a hybrid or a mongrel, sometimes returns in its
leaves, flowers, and fruit, either wholly or by segments, to both parent-
forms.
ON THE DIRECT OR IMMEDIATE ACTION OF THE MALE ELEMENT ON THE MOTHER FORM.
Another remarkable class of facts must be here considered, firstly, because
they have a high physiological importance, and secondly, because they have
been supposed to account for some cases of bud-variation. I refer to the
direct action of the male element, not in the ordinary way on the ovules,
but on certain parts of the female plant, or in case of animals on the
subsequent progeny of the female by a second male. I may premise that with
plants the ovarium and the coats of the ovules are obviously parts of the
female, and it could not have been anticipated that they would have been
affected by the pollen of a foreign variety or species, although the
development of the embryo, inside the embryonic sack, inside the ovule and
ovarium, of course, depends on the male element.
[Even as long ago as 1729 it was observed (11/127. 'Philosophical
Transact.' volume 43 1744-45 page 525.) that white and blue varieties of
the Pea, when planted near each other, mutually crossed, no doubt through
the agency of bees, and in the autumn blue and white peas were found within
the same pods. Wiegmann made an exactly similar observation in the present
century. The same result has followed several times when a variety with
peas of one colour has been artificially crossed by a differently-coloured
variety. (11/128. Mr. Goss 'Transact. Hort. Soc.' volume 5 page 234: and
Gartner 'Bastarderzeugung' 1849 ss. 81 and 499.) These statements led
Gartner, who was highly sceptical on the subject, carefully to try a long
series of experiments: he selected the most constant varieties, and the
result conclusively showed that the colour of the skin of the pea is
modified when pollen of a differently coloured variety is used. This
conclusion has since been confirmed by experiments made by the Rev. J.M.
Berkeley. (11/129. 'Gardener's Chronicle' 1854 page 404.)
Mr. Laxton of Stamford, whilst making experiments on peas for the express
purpose of ascertaining the influence of foreign pollen on the mother-
plant, has recently (11/130. Ibid 1866 page 900.) observed an important
additional fact. He fertilised the Tall Sugar-pea, which bears very thin
green pods, becoming brownish-white when dry, with pollen of the Purple-
podded pea, which, as its name expresses, has dark-purple pods with very
thick skin, becoming pale reddish purple when dry. Mr. Laxton has
cultivated the tall sugar-pea during twenty years, and has never seen or
heard of it producing a purple pod: nevertheless, a flower fertilised by
pollen from the purple-pod yielded a pod clouded with purplish-red which
Mr. Laxton kindly gave to me. A space of about two inches in length towards
the extremity of the pod, and a smaller space near the stalk, were thus
coloured. On comparing the colour with that of the purple pod, both pods
having been first dried and then soaked in water, it was found to be
identically the same; and in both the colour was confined to the cells
lying immediately beneath the outer skin of the pod. The valves of the
crossed pod were also decidedly thicker and stronger than those of the pods
of the mother-plant, but this may possibly have been an accidental
circumstance, for I know not how far their thickness is a variable
character in the Tall Sugar-pea.
The peas of the Tall Sugar-pea, when dry, are pale greenish-brown, thickly
covered with dots of dark purple so minute as to be visible only through a
lens, and Mr. Laxton has never seen or heard of this variety producing a
purple pea; but in the crossed pod one of the peas was of a uniform
beautiful violet-purple tint, and a second was irregularly clouded with
pale purple. The colour lies in the outer of the two coats which surround
the pea. As the peas of the purple-podded variety when dry are of a pale
greenish-buff, it would at first appear that this remarkable change of
colour in the peas in the crossed pod could not have been caused by the
direct action of the pollen of the purple-pod: but when we bear in mind
that this latter variety has purple flowers, purple marks on its stipules,
and purple pods; and that the Tall Sugar-pea likewise has purple flowers
and stipules, and microscopically minute purple dots on the peas, we can
hardly doubt that the tendency to the production of purple in both parents
has in combination modified the colour of the peas in the crossed pod.
After having examined these specimens, I crossed the same two varieties,
and the peas in one pod but not the pods themselves, were clouded and
tinted with purplish-red in a much more conspicuous manner than the peas in
the uncrossed pods produced at the same time by the same plants. I may
notice as a caution that Mr. Laxton sent me various other crossed peas
slightly, or even greatly, modified in colour; but the change in these
cases was due, as had been suspected by Mr. Laxton, to the altered colour
of the cotyledons, seen through the transparent coats of the peas; and as
the cotyledons are parts of the embryo, these cases are not in any way
remarkable.
Turning now to the genus Matthiola. The pollen of one kind of stock
sometimes affects the colour of the seeds of another kind, used as the
mother-plant. I give the following case the more readily, as Gartner
doubted similar statements previously made with respect to the stock by
other observers. A well-known horticulturist, Major Trevor Clarke, informs
me (11/131. See also a paper by this observer read before the International
Hort. and Bot. Congress of London 1866.) that the seeds of the large red-
flowered BIENNIAL stock, Matthiola annua (Cocardeau of the French), are
light brown, and those of the purple branching Queen stock (M. incana) are
violet-black; and he found that, when flowers of the red stock were
fertilised by pollen from the purple stock, they yielded about fifty per
cent of BLACK seeds. He sent me four pods from a red flowered plant, two of
which had been fertilised by their own pollen, and they included pale brown
seed; and two which had been crossed by pollen from the purple kind, and
they included seeds all deeply tinged with black. These latter seeds
yielded purple-flowered plants like their father; whilst the pale brown
seeds yielded normal red-flowered plants; and Major Clarke, by sowing
similar seeds, has observed on a greater scale the same result. The
evidence in this case of the direct action of the pollen of one species on
the colour of the seeds of another species appears to me conclusive.
Gallesio (11/132. 'Traite du Citrus' page 40.) fertilised the flowers of an
orange with pollen from the lemon; and one fruit thus produced bore a
longitudinal stripe of peel having the colour, flavour, and other
characters of the lemon. Mr. Anderson (11/133. 'Transact. Hort. Soc.'
volume 3 page 318. See also volume 5 page 65.) fertilised a green-fleshed
melon with pollen from a scarlet-fleshed kind; in two of the fruits "a
sensible change was perceptible: and four other fruits were somewhat
altered both internally and externally." The seeds of the two first-
mentioned fruits produced plants partaking of the good properties of both
parents. In the United States, where Cucurbitaceae are largely cultivated,
it is the popular belief (11/134. Prof. Asa Gray 'Proc. Acad. Sc.' Boston
volume 4 1860 page 21. I have received statements to the same effect from
other persons in the United States.) that the fruit is thus directly
affected hy foreign pollen; and I have received a similar statement with
respect to the cucumber in England. It is believed that grapes have been
thus affected in colour, size, and shape: in France a pale-coloured grape
had its juice tinted by the pollen of the dark-coloured Teinturier; in
Germany a variety bore berries which were affected by the pollen of two
adjoining kinds; some of the berries being only partially affected or
mottled. (11/135. For the French case see 'Journ. Hort. Soc.' volume 1 new
series 1866 page 50. For Germany see M. Jack quoted in Henfrey's 'Botanical
Gazette' volume 1 page 277. A case in England has recently been alluded to
by the Rev. J.M. Berkeley before the Hort. Soc. of London.)
As long ago as 1751 (11/136. 'Philosophical Transactions' volume 47 1751-52
page 206.) it was observed that, when differently-coloured varieties of
maize grew near each other, they mutually affected each other's seeds, and
this is now a popular belief in the United States. Dr. Savi (11/137.
Gallesio 'Teoria della Riproduzione' 1816 page 95.) tried the experiment
with care: he sowed yellow and black-seeded maize together, and on the same
ear some of the seeds were yellow, some black, and some mottled, the
differently coloured seeds being arranged irregularly or in rows. Prof.
Hildebrand has repeated the experiment (11/138. 'Bot. Zeitung' May 1868
page 326.) with the precaution of ascertaining that the mother-plant was
true. A kind bearing yellow grains was fertilised with pollen of a kind
having brown grains, and two ears produced yellow grains mingled with
others of a dirty violet tint. A third ear had only yellow grains, but one
side of the spindle was tinted of a reddish-brown; so that here we have the
important fact of the influence of the foreign pollen extending to the
axis. Mr. Arnold, in Canada, varied the experiment in an interesting
manner: "a female flower was subjected first to the action of pollen from a
yellow variety, and then to that from a white variety; the result was an
ear, each grain of which was yellow below and white above." (11/139. See
Dr. J. Stockton-Hough 'American Naturalist' January 1874 page 29.) With
other plants it has occasionally been observed that the crossed offspring
showed the influence of two kinds of pollen, but in this case the two kinds
affected the mother-plant.
Mr. Sabine states (11/140. 'Transact. Hort. Soc.' volume 5 page 69.) that
he has seen the form of the nearly globular seed-capsule of Amaryllis
vittata altered by the application of the pollen of another species, of
which the capsule has gibbous angles. With an allied genus, a well-known
botanist, Maximowicz, has described in detail the striking results of
reciprocally fertilising Lilium bulbiferum and davuricum with each other's
pollen. Each species produced fruit not like its own, but almost identical
with that of the pollen-bearing species; but from an accident only the
fruit of the latter species was carefully examined; the seeds were
intermediate in the development of their wings. (11/141. 'Bull. de l'Acad.
Imp. de St. Petersburg' tome 17 page 275, 1872. The author gives references
to those cases in the So1anaceae of fruit affected by foreign pollen, but
as it does not appear that the mother-plant was artificially fertilised, I
have not entered into details.)
Fritz Muller fertilised Cattleya leopoldi with pollen of Epidendron
cinnabarinum; and the capsules contained very few seeds; but these
presented a most wonderful appearance, which, from the description given,
two botanists, Hildebrand and Maximowicz, attribute to the direct action of
the pollen of the Epidendron. (11/142. 'Bot. Zeitung' September 1868 page
631. For Maximowicz's judgment see the paper last referred to.)
Mr. J. Anderson Henry (11/143. 'Journal of Horticulture' January 20, 1863
page 46.) crossed Rhododendron dalhousiae with the pollen of R. nuttallii,
which is one of the largest-flowered and noblest species of the genus. The
largest pod produced by the former species, when fertilised with its own
pollen, measured 1 2/8 inch in length and 1 1/2 in girth; whilst three of
the pods which had been fertilised by pollen of R. nuttallii measured 1 5/8
inch in length and no less than 2 inches in girth. Here the effect of the
foreign pollen was apparently confined to increasing the size of the
ovarium; but we must be cautious in assuming, as the following case shows,
that size had been transferred from the male parent to the capsule of the
female plant. Mr. Henry fertilised Arabis blepharophylla with pollen of A.
soyeri, and the pods thus produced, of which he was so kind as to send me
detailed measurements and sketches, were much larger in all their
dimensions than those naturally produced by either the male or female
parent-species. In a future chapter we shall see that the organs of
vegetation in hybrid plants, independently of the character of either
parent, are sometimes developed to a monstrous size; and the increased size
of the pods in the foregoing cases may be an analogous fact. On the other
hand, M. de Saporta informs me that an isolated female plant of Pistacia
vera is very apt to be fertilised by the pollen of neighbouring plants of
P. terebinthus, and in this case the fruits are only half their proper
size, which he attributes to the influence of the pollen of P. terebinthus.
No case of the direct action of the pollen of one variety on another is
better authenticated or more remarkable than that of the common apple. The
fruit here consists of the lower part of the calyx and of the upper part of
the flower-peduncle (11/144. See on this head the high authority of Prof.
Decaisne in a paper translated in 'Journ. Hort. Soc.' volume 1 new series
1866 page 48.) in a metamorphosed condition, so that the effect of the
foreign pollen has extended even beyond the limits of the ovarium. Cases of
apples thus affected were recorded by Bradley in the early part of the last
century; and other cases are given in old volumes of the 'Philosophical
Transactions' (11/145. Volume 43 1744-45 page 525 volume 45 1747-48 page
602.); in one of these a Russeting apple and an adjoining kind mutually
affected each other's fruit; and in another case a smooth apple affected a
rough-coated kind. Another instance has been given (11/146. 'Transact.
Hort. Soc.' volume 5 pages 65 and 68. See also Prof. Hildebrand with a
coloured figure in 'Bot. Zeitung' May 15, 1868 page 327. Puvis also has
collected 'De La Degeneration' 1837 page 36) several other instances; but
it is not in all cases possible to distinguish between the direct action of
foreign pollen and bud-variations.) of two very different apple-trees
growing close to each other, which bore fruit resembling each other, but
only on the adjoining branches. It is, however, almost superfluous to
adduce these or other cases, after that of the St. Valery apple, the
flowers which, from the abortion of the stamens, do not produce pollen, but
are fertilised by the girls of the neighbourhood with pollen of many kinds;
and they bear fruit, "differing from one another in size, flavour, and
colour, but resembling in character the hermaphrodite kinds by which they
have been fertilised." (11/147. T. de Clermont-Tonnerre in 'Mem. de la Soc.
Linn. de Paris' tome 3 1825 page 164.)]
I have now shown, on the authority of several excellent observers, in the
case of plants belonging to widely different orders, that the pollen of one
species or variety, when applied to the female of a distinct form,
occasionally causes the coats of the seeds, the ovarium or fruit, including
even the calyx and upper part of the peduncle of the apple, and the axis of
the ear in maize, to be modified. Sometimes the whole ovarium or all the
seeds are thus affected; sometimes only a certain number of the seeds, as
in the case of the pea, or only a part of the ovarium, as with the striped
orange, mottled grapes, and maize, is thus affected. It must not be
supposed that any direct or immediate effect invariably follows the use of
foreign pollen: this is far from being the case; nor is it known on what
conditions the result depends. Mr. Knight (11/148. 'Transact. of Hort.
Soc.' volume 5 page 68.) expressly states that he has never seen the fruit
thus affected, though he crossed thousands of apple and other fruit-trees.
There is not the least reason to believe that a branch which has borne seed
or fruit directly modified by foreign pollen is itself affected, so as
afterwards to produce modified buds; such an occurrence, from the temporary
connection of the flower with the stem, would be hardly possible. Hence,
but very few, if any, of the cases of bud-variation in the fruit of trees,
given in the early part of this chapter can be accounted for by the action
of foreign pollen; for such fruits have commonly been propagated by budding
or grafting. It is also obvious that changes of colour in flowers, which
necessarily supervene long before they are ready for fertilisation, and
changes in the shape or colour of leaves, when due to the appearance of
modified buds, can have no relation to the action of foreign pollen.
The proofs of the action of foreign pollen on the mother-plant have been
given in considerable detail, because this action, as we shall see in a
future chapter, is of the highest theoretical importance, and because it is
in itself a remarkable and apparently anomalous circumstance. That it is
remarkable under a physiological point of view is clear, for the male
element not only affects, in accordance with its proper function, the germ,
but at the same time various parts of the mother-plant, in the same manner,
as it affects the same part in the seminal offspring from the same two
parents. We thus learn that an ovule is not indispensable for the reception
of the influence of the male element. But this direct action of the male
element is not so anomalous as it at first appears, for it comes into play
in the ordinary fertilisation of many flowers. Gartner gradually increased
the number of pollen grains until he succeeded in fertilising a Malva, and
has (11/149. Beitrage zur Kenntniss der Befruchtung' 1844 s. 347-351.)
proved that many grains are first expended in the development, or, as he
expresses it, in the satiation, of the pistil and ovarium. Again, when one
plant is fertilised by a widely distinct species, it often happens that the
ovarium is fully and quickly developed without any seeds being formed; or
the coats of the seeds are formed without any embryo being developed
within. Prof. Hildebrand, also, has lately shown (11/150. 'Die
Fruchtbildung der Orchideen, ein Beweis fur die doppelte Wirkung des
Pollens' 'Botanische Zeitung' No. 44 et seq. October 30, 1865; and August
4, 1865 s. 249.) that, in the normal fertilisation of several Orchideae,
the action of the plant's own pollen is necessary for the development of
the ovarium; and that this development takes place not only long before the
pollen-tubes have reached the ovules, but even before the placentae and
ovules have been formed; so that with these orchids the pollen acts
directly on the ovarium. On the other hand, we must not overrate the
efficacy of pollen in the case of hybridised plants, for an embryo may be
formed and its influence excite the surrounding tissues of the mother-
plant, and then perish at a very early age and be thus overlooked. Again,
it is well known that with many plants the ovarium may be fully developed,
though pollen be wholly excluded. Lastly, Mr. Smith, the late Curator at
Kew (as I hear through Dr. Hooker), observed with an orchid, the Bonatea
speciosa, the singular fact that the development of the ovarium could be
effected by the mechanical irritation of the stigma. Nevertheless, from the
number of the pollen-grains expended "in the satiation of the ovarium and
pistil,"--from the generality of the formation of the ovarium and seed-
coats in hybridised plants which produce no seeds,--and from Dr.
Hildebrand's observations on orchids, we may admit that in most cases the
swelling of the ovarium, and the formation of the seed-coats are at least
aided, if not wholly caused, by the direct action of the pollen,
independently of the intervention of the fertilised germ. Therefore, in the
previously given cases we have only to believe in the further power of
pollen, when applied to a distinct species or variety, to influence the
shape, size, colour, texture, etc., of certain parts of the mother-plant.
Turning now to the animal kingdom. If we could imagine the same flower to
yield seeds during successive years, then it would not be very surprising
that a flower of which the ovarium had been modified by foreign pollen
should next year produce, when self-fertilised, offspring modified by the
previous male influence. Closely analogous cases have actually occurred
with animals. In the case often quoted from Lord Morton (11/151. 'Philos.
Transact.' 1821 page 20.) a nearly purely-bred Arabian chestnut mare bore a
hybrid to a quagga; she was subsequently sent to Sir Gore Ouseley, and
produced two colts by a black Arabian horse. These colts were partially
dun-coloured, and were striped on the legs more plainly than the real
hybrid, or even than the quagga. One of the two colts had its neck and some
other parts of its body plainly marked with stripes. Stripes on the body,
not to mention those on the legs, are extremely rare,--I speak after having
long attended to the subject,--with horses of all kinds in Europe, and are
almost unknown in the case of Arabians. But what makes the case still more
striking is that in these colts the hair of the mane resembled that of the
quagga, being short, stiff, and upright. Hence there can be no doubt that
the quagga affected the character of the offspring subsequently begot by
the black Arabian horse. Mr. Jenner Weir informs me of a strictly parallel
case: his neighbour Mr. Lethbridge, of Blackheath, has a horse, bred by
Lord Mostyn, which had previously borne a foal by a quagga. This horse is
dun with a dark stripe down the back, faint stripes on the forehead between
the eyes, plain stripes on the inner side of the fore-legs and rather more
faint ones on the hind-legs, with no shoulder-stripe. The mane grows much
lower on the forehead than in the horse, but not so low as in the quagga or
zebra. The hoofs are proportionally longer than in the horse,--so much so
that the farrier who first shod this animal, and knew nothing of its
origin, said, "Had I not seen I was shoeing a horse, I should have thought
I was shoeing a donkey."
With respect to the varieties of our domesticated animals, many similar and
well-authenticated facts have been published (11/152. Dr. Alex. Harvey on
'A remarkable Effect of Cross-breeding' 1851. On the 'Physiology of
Breeding' by Mr. Reginald Orton 1855. 'Intermarriage' by Alex. Walker 1837.
'L'Heredite Naturelle' by Dr. Prosper Lucas tome 2 page 58. Mr. W. Sedgwick
in 'British and Foreign Medico-Chirurgical Review' 1863 July page 183.
Bronn in his 'Geschichte der Natur' 1843 b. 2 s. 127 has collected several
cases with respect to mares, sows, and dogs. Mr. W.C.L. Martin ('History of
the Dog' 1845 page 104) says he can personally vouch for the influence of
the male parent on subsequent litters by other dogs. A French poet, Jacques
Savary, who wrote in 1665 on dogs, was aware of this singular fact. Dr.
Bowerbank has given us the following striking case:--A black, hairless
Barbary bitch was first accidentally impregnated by a mongrel spaniel with
long brown hair, and she produced five puppies, three of which were
hairless and two covered with SHORT brown hair. The next time she was put
to a black, hairless Barbary dog; "but the mischief had been implanted in
the mother, and again about half the litter looked like pure Barbarys, and
the other half like the SHORT-haired progeny of the first father." I have
given in the text one case with pigs; an equally striking one has been
recently published in Germany, 'Illust. Landwirth. Zeitung' 1868 November
17 page 143. It is worth notice that farmers in S. Brazil (as I hear from
Fritz Muller), and at the C. of Good Hope (as I have heard from two
trustworthy persons) are convinced that mares which have once borne mules,
when subsequently put to horses, are extremely liable to produce colts,
striped like a mule. Dr. Wilckens of Pogarth gives ('Jahrbuch
Landwirthschaft' 2 1869 page 325) a striking and analogous case. A merino
ram, having two small lappets or flaps of skin on the neck, was in the
winter of 1861-62 put to several Merino ewes, all of whom bore lambs with
similar flaps on their necks. The ram was killed in the spring of 1862 and
subsequently to his death the ewes were put to other Merino rams, and in
1863 to Southdown rams, none of whom ever have neck lappets: nevertheless,
even as long afterwards as 1867, several of these ewes produced lambs
bearing these appendages.), and others have been communicated to me,
plainly showing the influence of the first male on the progeny subsequently
borne by the mother to other males. It will suffice to give a single
instance, recorded in the 'Philosophical Transactions,' in a paper
following that by Lord Morton: Mr. Giles put a sow of Lord Western's black
and white Essex breed to a wild boar of a deep chestnut colour; and the
"pigs produced partook in appearance of both boar and sow, but in some the
chestnut colour of the boar strongly prevailed." After the boar had long
been dead, the sow was put to a boar of her own black and white breed--a
kind which is well known to breed very true and never to show any chestnut
colour,--yet from this union the sow produced some young pigs which were
plainly marked with the same chestnut tint as in the first litter. Similar
cases have so frequently occurred, that careful breeders avoid putting a
choice female of any animal to an inferior male, on account of the injury
to her subsequent progeny which may be expected to follow.
Some physiologists have attempted to account for these remarkable results
from a previous impregnation, by the imagination of the mother having been
strongly affected; but it will hereafter be seen that there are very slight
grounds for any such belief. Other physiologists attribute the result to
the close attachment and freely intercommunicating blood-vessels between
the modified embryo and mother. But the analogy from the action of foreign
pollen on the ovarium, seed-coats, and other parts of the mother-plant,
strongly supports the belief that with animals the male element acts
directly on the female, and not through the crossed embryo. With birds
there is no close connection between the embryo and mother; yet a careful
observer, Dr. Chapuis, states (11/153. 'Le Pigeon Voyageur Belge' 1865 page
59.) that with pigeons the influence of a first male sometimes makes itself
perceived in the succeeding broods; but this statement requires
confirmation.
CONCLUSION AND SUMMARY OF THE CHAPTER.
The facts given in the latter half of this chapter are well worthy of
consideration, as they show us in how many extraordinary modes the union of
one form with another may lead to the modification of the seminal offspring
or of the buds, afterwards produced.
There is nothing surprising in the offspring of species or varieties
crossed in the ordinary manner being modified; but the case of two plants
within the same seed, which cohere and differ from each other, is curious.
When a bud is formed after the cellular tissue of two species or two
varieties have been united, and it partakes of the characters of both
parents, the case is wonderful. But I need not here repeat what has been so
lately said on this subject. We have also seen that in the case of plants
the male element may affect in a direct manner the tissues of the mother,
and with animals may lead to the modification of her future progeny. In the
vegetable kingdom the offspring from a cross between two species or
varieties, whether effected by seminal generation or by grafting, often
revert, to a greater or less degree, in the first or in a succeeding
generation, to the two parent-forms; and this reversion may affect the
whole flower, fruit, or leaf-bud, or only the half or a smaller segment of
a single organ. In some cases, however, such segregation of character
apparently depends on an incapacity for union rather than on reversion, for
the flowers or fruit which are first produced display by segments the
characters of both parents. The various facts here given ought to be well
considered by any one who wishes to embrace under a single point of view
the many modes of reproduction by gemmation, division, and sexual union,
the reparation of lost parts, variation, inheritance, reversion, and other
such phenomena. Towards the close of the second volume I shall attempt to
connect these facts together by the hypothesis of pangenesis.
In the early half of the present chapter I have given a long list of plants
in which through bud-variation, that is, independently of reproduction by
seed, the fruit has suddenly become modified in size, colour, flavour,
hairiness, shape, and time of maturity; flowers have similarly changed in
shape, colour, in being double, and greatly in the character of the calyx;
young branches or shoots have changed in colour, in bearing spines and in
habit of growth, as in climbing or in weeping; leaves have changed in
becoming variegated, in shape, period of unfolding, and in their
arrangement on the axis. Buds of all kinds, whether produced on ordinary
branches or on subterranean stems, whether simple or much modified and
supplied with a stock of nutriment, as in tubers and bulbs, are all liable
to sudden variations of the same general nature.
In the list, many of the cases are certainly due to reversion to characters
not acquired from a cross, but which were formerly present and have since
been lost for a longer or shorter time;--as when a bud on a variegated
plant produces plain leaves, or when the variously-coloured flowers of the
Chrysanthemum revert to the aboriginal yellow tint. Many other cases
included in the list are probably due to the plants being of crossed
parentage, and to the buds reverting either completely or by segments to
one of the two parent-forms. (11/154. It may be worth while to call
attention to the several means by which flowers and fruit become striped or
mottled. Firstly, by the direct action of the pollen of another variety or
species, as in the cases given of oranges and maize. Secondly, in crosses
of the first generation, when the colours of the two parents do not readily
unite, as with Mirabilis and Dianthus. Thirdly, in crossed plants of a
subsequent generation by reversion, through either bud or seminal
generation. Fourthly, by reversion to a character not originally gained by
a cross, but which had long been lost, as with white-flowered varieties,
which we shall hereafter see often become striped with some other colour.
Lastly, there are cases, as when peaches are produced with a half or
quarter of the fruit like a nectarine, in which the change is apparently
due to mere variation, through either bud or seminal generation.)
We may suspect that the strong tendency in the Chrysanthemum to produce by
bud-variation differently-coloured flowers, results from the varieties
having been at some time intentionally or accidentally crossed; and this is
certainly the case with some kinds of Pelargonium. So it may be to a large
extent with the bud-varieties of the Dahlia, and with the "broken colours
"of Tulips. When, however, a plant reverts by bud-variation to its two
parent forms, or to one of them, it sometimes does not revert perfectly,
but assumes a somewhat new character,--of which fact, instances have been
given, and Carriere gives (11/155. 'Production des Varietes' page 37.)
another in the cherry.
Many cases of bud-variation, however, cannot be attributed to reversion,
but to so-called spontaneous variability, as is so common with cultivated
plants raised from seed. As a single variety of the Chrysanthemum has
produced by buds six other varieties, and as one variety of the gooseberry
has borne at the same time four distinct kinds of fruit, it is scarcely
possible to believe that all these variations are due to reversion. We can
hardly believe, as remarked in a previous chapter, that all the many
peaches which have yielded nectarine-buds are of crossed parentage. Lastly,
in such cases as that of the moss-rose, with its peculiar calyx, and of the
rose which bears opposite leaves, in that of the Imatophyllum, etc., there
is no known natural species or variety from which the characters in
question could have been derived by a cross. We must attribute all such
cases to the appearance of absolutely new characters in the buds. The
varieties which have thus arisen cannot be distinguished by any external
character from seedlings; this is notoriously the case with the varieties
of the Rose, Azalea, and many other plants. It deserves notice that all the
plants which have yielded bud-variations have likewise varied greatly by
seed.
The plants which have varied by buds belong to so many orders that we may
infer that almost every plant would be liable to variation, if placed under
the proper exciting conditions. These conditions, as far as we can judge,
mainly depend on long-continued and high cultivation; for almost all the
plants in the foregoing list are perennials, and have been largely
propagated in many soils, under different climates, by cuttings, offsets,
bulbs, tubers, and especially by budding or grafting. The instances of
annuals varying by buds, or producing on the same plant differently
coloured flowers, are comparatively rare: Hopkirk (11/156. 'Flora Anomala'
page 164.) has seen this with Convolvulus tricolor; and it is not uncommon
with the Balsam and annual Delphinium. According to Sir R. Schomburgk,
plants from the warmer temperate regions, when cultivated under the hot
climate of St. Domingo, are eminently liable to bud-variation. I am
informed by Mr. Sedgwick that moss-roses which have often been taken to
Calcutta always there lose their mossiness; but change of climate is by no
means a necessary contingent, as we see with the gooseberry, currant, and
in many other cases. Plants living under their natural conditions are very
rarely subject to bud-variation. Variegated leaves have, however, been
observed under such circumstances; and I have given an instance of
variation by buds on an ash-tree planted in ornamental grounds, but it is
doubtful whether such a tree can be considered as living under strictly
natural conditions. Gartner has seen white and dark-red flowers produced
from the same root of the wild Achillea millefolium; and Prof. Caspary has
seen a completely wild Viola lutea bearing flowers of two different colours
and sizes. (11/157. 'Schriften der physisch-okon. Gesell. zu Konigsberg' b.
6 February 3, 1865 s. 4.)
As wild plants are so rarely liable to bud-variation, whilst highly
cultivated plants long propagated by artificial means have yielded many
varieties by this form of reproduction, we are led through a series such as
the following,--namely, all the eyes in the same tuber of the potato
varying in the same manner,--all the fruit on a purple plum-tree suddenly
becoming yellow,--all the fruit on a double-flowered almond suddenly
becoming peach like,--all the buds on grafted trees being in a very slight
degree affected by the stock on which they have been worked,--all the
flowers on a transplanted heartsease changing for a time in colour, size,
and shape,--we are led by such a series to look at every case of bud-
variation as the direct result of the conditions of life to which the plant
has been exposed. On the other hand, plants of the same variety may be
cultivated in two adjoining beds, apparently under exactly the same
conditions, and those in the one bed, as Carriere insists (11/158.
'Production des Varietes' pages 58, 70.) will produce many bud-variations,
and those in the other not a single one. Again, if we look to such cases as
that of a peach-tree which, after having been cultivated by tens of
thousands during many years in many countries, and after having annually
produced millions of buds, all of which have apparently been exposed to
precisely the same conditions, yet at last suddenly produces a single bud
with its whole character greatly transformed, we are driven to the
conclusion that the transformation stands in no DIRECT relation to the
conditions of life.
We have seen that varieties produced from seeds and from buds resemble each
other so closely in general appearance that they cannot be distinguished.
Just as certain species and groups of species, when propagated by seed, are
more variable than other species or genera, so it is in the case of certain
bud-varieties. Thus, the Queen of England Chrysanthemum has produced by
this latter process no less than six, and Rollisson's Unique Pelargonium
four distinct varieties; moss-roses have also produced several other moss-
roses. The Rosaceae have varied by buds more than any other group of
plants; but this may be in large part due to so many members having been
long cultivated; but within this same group, the peach has often varied by
buds, whilst the apple and pear, both grafted trees extensively cultivated,
have afforded, as far as I can ascertain, extremely few instances of bud-
variation.
The law of analogous variation holds good with varieties produced by buds,
as with those produced from seed: more than one kind of rose has sported
into a moss-rose; more than one kind of camellia has assumed an hexagonal
form; and at least seven or eight varieties of the peach have produced
nectarines.
The laws of inheritance seem to be nearly the same with seminal and bud-
varieties. We know how commonly reversion comes into play with both, and it
may affect the whole, or only segments of a leaf, flower, or fruit. When
the tendency to reversion affects many buds on the same tree, it becomes
covered with different kinds of leaves, flowers, or fruit; but there is
reason to believe that such fluctuating varieties have generally arisen
from seed. It is well known that, out of a number of seedling varieties,
some transmit their character much more truly by seed than others; so with
bud-varieties, some retain their character by successive buds more truly
than others; of which instances have been given with two kinds of
variegated Euonymus and with certain kinds of tulips and pelargoniums.
Notwithstanding the sudden production of bud-varieties, the characters thus
acquired are sometimes capable of transmission by seminal reproduction: Mr.
Rivers has found that moss-roses generally reproduce themselves by seed;
and the mossy character has been transferred by crossing from one species
of rose to another. The Boston nectarine, which appeared as a bud-
variation, produced by seed a closely allied nectarine. On the other hand,
seedlings from some bud-variations have proved variable to an extreme
degree. (11/159. Carriere 'Production des Varietes' page 39.) We have also
heard, on the authority of Mr. Salter, that seeds taken from a branch with
leaves variegated through bud-variation, transmit this character very
feebly; whilst many plants, which were variegated as seedlings, transmit
variegation to a large proportion of their progeny.
Although I have been able to collect a good many cases of bud-variation, as
shown in the previous lists, and might probably, by searching foreign
horticultural works, have collected very many more cases, yet their total
number is as nothing in comparison with that of seminal varieties. With
seedlings raised from the more variable cultivated plants, the variations
are almost infinitely numerous, but their differences are generally slight:
only at long intervals of time a strongly marked modification appears. On
the other hand, it is a singular and inexplicable fact that, when plants
vary by buds, the variations, though they occur with comparative rarity,
are often, or even generally, strongly pronounced. It struck me that this
might perhaps be a delusion, and that slight changes often occurred in
buds, but were overlooked or not recorded from being of no value.
Accordingly, I applied to two great authorities on this subject, namely, to
Mr. Rivers with respect to fruit-trees, and to Mr. Salter with respect to
flowers. Mr. Rivers is doubtful, but does not remember having noticed very
slight variations in fruit-buds. Mr. Salter informs me that with flowers
such do occur, but, if propagated, they generally lose their new character
in the following year; yet he concurs with me that bud-variations usually
at once assume a decided and permanent character. We can hardly doubt that
this is the rule, when we reflect on such cases as that of the peach, which
has been so carefully observed, and of which such trifling seminal
varieties have been propagated, yet this tree has repeatedly produced by
bud-variation nectarines, and only twice (as far as I can learn) any other
variety, namely, the Early and Late Grosse Mignonne peaches; and these
differ from the parent-tree in hardly any character except the period of
maturity.
To my surprise, I hear from Mr. Salter that he brings the principle of
selection to bear on variegated plants propagated by buds, and has thus
greatly improved and fixed several varieties. He informs me that at first a
branch often produces variegated leaves on one side alone, and that the
leaves are marked only with an irregular edging or with a few lines of
white and yellow. To improve and fix such varieties, he finds it necessary
to encourage the buds at the bases of the most distinctly marked leaves,
and to propagate from them alone. By following with perseverance this plan
during three or four successive seasons, a distinct and fixed variety can
generally be secured.
Finally, the facts given in this chapter prove in how close and remarkable
a manner the germ of a fertilised seed and the small cellular mass forming
a bud, resemble each other in all their functions--in their power of
inheritance with occasional reversion,--and in their capacity for variation
of the same general nature, in obedience to the same laws. This
resemblance, or rather identity of character, is shown in the most striking
manner by the fact that the cellular tissue of one species or variety, when
budded or grafted on another, may give rise to a bud having an intermediate
character. We have seen that variability does not depend on sexual
generation, though much more frequently its concomitant than of bud
reproduction. We have seen that bud-variability is not solely dependent on
reversion or atavism to long-lost characters, or to those formerly acquired
from a cross, but appears often to be spontaneous. But when we ask
ourselves what is the cause of any particular bud-variation, we are lost in
doubt, being driven in some cases to look to the direct action of the
external conditions of life as sufficient, and in other cases to feel a
profound conviction that these have played a quite subordinate part, of not
more importance than the nature of the spark which ignites a mass of
combustible matter.
CHAPTER 1.XII.
INHERITANCE.
WONDERFUL NATURE OF INHERITANCE.
PEDIGREES OF OUR DOMESTICATED ANIMALS.
INHERITANCE NOT DUE TO CHANCE.
TRIFLING CHARACTERS INHERITED.
DISEASES INHERITED.
PECULIARITIES IN THE EYE INHERITED.
DISEASES IN THE HORSE.
LONGEVITY AND VIGOUR.
ASYMMETRICAL DEVIATIONS OF STRUCTURE.
POLYDACTYLISM AND REGROWTH OF SUPERNUMERARY DIGITS AFTER AMPUTATION.
CASES OF SEVERAL CHILDREN SIMILARLY AFFECTED FROM NON-AFFECTED PARENTS.
WEAK AND FLUCTUATING INHERITANCE: IN WEEPING TREES, IN DWARFNESS, COLOUR OF
FRUIT AND FLOWERS.
COLOUR OF HORSES.
NON-INHERITANCE IN CERTAIN CASES.
INHERITANCE OF STRUCTURE AND HABITS OVERBORNE BY HOSTILE CONDITIONS OF
LIFE, BY INCESSANTLY RECURRING VARIABILITY, AND BY REVERSION.
CONCLUSION.
The subject of inheritance is an immense one, and has been treated by many
authors. One work alone, 'De l'Heredite Naturelle' by Dr. Prosper Lucas,
runs to the length of 1562 pages. We must confine ourselves to certain
points which have an important bearing on the general subject of variation,
both with domestic and natural productions. It is obvious that a variation
which is not inherited throws no light on the derivation of species, nor is
of any service to man, except in the case of perennial plants, which can be
propagated by buds.
If animals and plants had never been domesticated, and wild ones alone had
been observed, we should probably never have heard the saying, that "like
begets like." The proposition would have been as self-evident as that all
the buds on the same tree are alike, though neither proposition is strictly
true. For, as has often been remarked, probably no two individuals are
identically the same. All wild animals recognise each other, which shows
that there is some difference between them; and when the eye is well
practised, the shepherd knows each sheep, and man can distinguish a fellow-
man out of millions on millions of other men. Some authors have gone so far
as to maintain that the production of slight differences is as much a
necessary function of the powers of generation, as the production of
offspring like their parents. This view, as we shall see in a future
chapter, is not theoretically probable, though practically it holds good.
The saying that "like begets like" has, in fact, arisen from the perfect
confidence felt by breeders, that a superior or inferior animal will
generally reproduce its kind; but this very superiority or inferiority
shows that the individual in question has departed slightly from its type.
The whole subject of inheritance is wonderful. When a new character arises,
whatever its nature may be, it generally tends to be inherited, at least in
a temporary and sometimes in a most persistent manner. What can be more
wonderful than that some trifling peculiarity, not primordially attached to
the species, should be transmitted through the male or female sexual cells,
which are so minute as not to be visible to the naked eye, and afterwards
through the incessant changes of a long course of development, undergone
either in the womb or in the egg, and ultimately appear in the offspring
when mature, or even when quite old, as in the case of certain diseases? Or
again, what can be more wonderful than the well-ascertained fact that the
minute ovule of a good milking cow will produce a male, from whom a cell,
in union with an ovule, will produce a female, and she, when mature, will
have large mammary glands, yielding an abundant supply of milk, and even
milk of a particular quality? Nevertheless, the real subject of surprise
is, as Sir H. Holland has well remarked (12/1. 'Medical Notes and
Reflections' 3rd edition 1855 page 267.) not that a character should be
inherited, but that any should ever fail to be inherited. In a future
chapter, devoted to an hypothesis which I have termed pangenesis, an
attempt will be made to show the means by which characters of all kinds are
transmitted from generation to generation.
Some writers (12/2. Mr. Buckle in his 'History of Civilisation' expresses
doubts on the subject, owing to the want of statistics. See also Mr. Bowen,
Professor of Moral Philosophy, in 'Proc. American Acad. of Sciences' volume
5 page 102.), who have not attended to natural history, have attempted to
show that the force of inheritance has been much exaggerated. The breeders
of animals would smile at such simplicity; and if they condescended to make
any answer, might ask what would be the chance of winning a prize if two
inferior animals were paired together? They might ask whether the half-wild
Arabs were led by theoretical notions to keep pedigrees of their horses?
Why have pedigrees been scrupulously kept and published of the Shorthorn
cattle, and more recently of the Hereford breed? Is it an illusion that
these recently improved animals safely transmit their excellent qualities
even when crossed with other breeds? have the Shorthorns, without good
reason, been purchased at immense prices and exported to almost every
quarter of the globe, a thousand guineas having been given for a bull? With
greyhounds pedigrees have likewise been kept, and the names of such dogs,
as Snowball, Major, etc., are as well known to coursers as those of Eclipse
and Herod on the turf. Even with the Gamecock, pedigrees of famous strains
were formerly kept, and extended back for a century. With pigs, the
Yorkshire and Cumberland breeders "preserve and print pedigrees;" and to
show how such highly-bred animals are valued, I may mention that Mr. Brown,
who won all the first prizes for small breeds at Birmingham in 1850, sold a
young sow and boar of his breed to Lord Ducie for 43 guineas; the sow alone
was afterwards sold to the Rev. F. Thursby for 65 guineas; who writes, "She
paid me very well, having sold her produce for 300 pounds, and having now
four breeding sows from her." (12/3. For greyhounds see Low 'Domestic
Animals of the British Islands' 1845 page 721. For game-fowls see 'The
Poultry Book' by Mr. Tegetmeier 1866 page 123. For pigs see Mr. Sidney's
edition of 'Youatt on the Pig' 1860 pages 11, 22.) Hard cash paid down,
over and over again, is an excellent test of inherited superiority. In
fact, the whole art of breeding, from which such great results have been
attained during the present century, depends on the inheritance of each
small detail of structure. But inheritance is not certain; for if it were,
the breeder's art (12/4. 'The Stud Farm' by Cecil page 39.) would be
reduced to a certainty, and there would be little scope left for that
wonderful skill and perseverance shown by the men who have left an enduring
monument of their success in the present state of our domesticated animals.
It is hardly possible, within a moderate compass, to impress on the mind of
those who have not attended to the subject, the full conviction of the
force of inheritance which is slowly acquired by rearing animals, by
studying the many treatises which have been published on the various
domestic animals, and by conversing with breeders. I will select a few
facts of the kind, which, as far as I can judge, have most influenced my
own mind. With man and the domestic animals, certain peculiarities have
appeared in an individual, at rare intervals, or only once or twice in the
history of the world, but have reappeared in several of the children and
grandchildren. Thus Lambert, "the porcupine-man," whose skin was thickly
covered with warty projections, which were periodically moulted, had all
his six children and two grandsons similarly affected. (12/5.
'Philosophical Transactions' 1755 page 23. I have seen only second-hand
accounts of the two grandsons. Mr. Sedgwick, in a paper to which I shall
hereafter often refer, states that FOUR generations were affected, and in
each the males alone.) The face and body being covered with long hair,
accompanied by deficient teeth (to which I shall hereafter refer), occurred
in three successive generations in a Siamese family; but this case is not
unique, as a woman (12/6. Barbara Van Beck, figured, as I am informed by
the Rev. W.D. Fox, in Woodburn's 'Gallery of Rare Portraits' 1816 volume 2)
with a completely hairy face who was exhibited in London in 1663, and
another instance has recently occurred. Colonel Hallam (12/7. 'Proc.
Zoolog. Soc.' 1833 page 16.) has described a race of two-legged pigs, "the
hinder extremities being entirely wanting;" and this deficiency was
transmitted through three generations. In fact, all races presenting any
remarkable peculiarity, such as solid-hoofed swine, Mauchamp sheep, niata
cattle, etc., are instances of the long-continued inheritance of rare
deviations of structure.
When we reflect that certain extraordinary peculiarities have thus appeared
in a single individual out of many millions, all exposed in the same
country to the same general conditions of life, and, again, that the same
extraordinary peculiarity has sometimes appeared in individuals living
under widely different conditions of life, we are driven to conclude that
such peculiarities are not directly due to the action of the surrounding
conditions, but to unknown laws acting on the organisation or constitution
of the individual;--that their production stands in hardly closer relation
to the conditions of life than does life itself. If this be so, and the
occurrence of the same unusual character in the child and parent cannot be
attributed to both having been exposed to the same unusual conditions, then
the following problem is worth consideration, as showing that the result
cannot be due, as some authors have supposed, to mere coincidence, but must
be consequent on the members of the same family inheriting something in
common in their constitution. Let it be assumed that, in a large
population, a particular affection occurs on an average in one out of a
million, so that the a priori chance that an individual taken at random
will be so affected is only one in a million. Let the population consist of
sixty millions, composed, we will assume, of ten million families, each
containing six members. On these data, Professor Stokes has calculated for
me that the odds will be no less than 8333 millions to 1 that in the ten
million families there will not be even a single family in which one parent
and two children will be affected by the peculiarity in question. But
numerous instances could be given, in which several children have been
affected by the same rare peculiarity with one of their parents; and in
this case, more especially if the grandchildren be included in the
calculation, the odds against mere coincidence become something prodigious,
almost beyond enumeration.
In some respects the evidence of inheritance is more striking when we
consider the reappearance of trifling peculiarities. Dr. Hodgkin formerly
told me of an English family in which, for many generations, some members
had a single lock differently coloured from the rest of the hair. I knew an
Irish gentleman, who, on the right side of his head, had a small white lock
in the midst of his dark hair: he assured me that his grandmother had a
similar lock on the same side, and his mother on the opposite side. But it
is superfluous to give instances; every shade of expression, which may
often be seen alike in parents and children, tells the same story. On what
a curious combination of corporeal structure, mental character, and
training, handwriting depends! yet every one must have noted the occasional
close similarity of the handwriting in father and son, although the father
had not taught his son. A great collector of autographs assured me that in
his collection there were several signatures of father and son hardly
distinguishable except by their dates. Hofacker, in Germany, remarks on the
inheritance of handwriting; and it has even been asserted that English boys
when taught to write in France naturally cling to their English manner of
writing; but for so extraordinary a statement more evidence is requisite.
(12/8. Hofacker 'Ueber die Eigenschaften' etc. 1828 s. 34. With respect to
France, Report by Pariset in 'Comptes Rendus' 1847 page 592.) Gait,
gestures, voice, and general bearing are all inherited, as the illustrious
Hunter and Sir A. Carlisle have insisted. (12/9. Hunter as quoted in
Harlan's 'Med. Researches' page 530. Sir A. Carlisle 'Phil. Transact.' 1814
page 94.) My father communicated to me some striking instances, in one of
which a man died during the early infancy of his son, and my father, who
did not see this son until grown up and out of health, declared that it
seemed to him as if his old friend had risen from the grave, with all his
highly peculiar habits and manners. Peculiar manners pass into tricks, and
several instances could be given of their inheritance; as in the case,
often quoted, of the father who generally slept on his back, with his right
leg crossed over the left, and whose daughter, whilst an infant in the
cradle, followed exactly the same habit, though an attempt was made to cure
her. (12/10. Girou de Buzareingues 'De la Generation' page 282. I have
given an analogous case in my book on 'The Expression of the Emotions.') I
will give one instance which has fallen under my own observation, and which
is curious from being a trick associated with a peculiar state of mind,
namely, pleasureable emotion. A boy had the singular habit, when pleased,
of rapidly moving his fingers parallel to each other, and, when much
excited, of raising both hands, with the fingers still moving, to the sides
of his face on a level with the eyes; when this boy was almost an old man,
he could still hardly resist this trick when much pleased, but from its
absurdity concealed it. He had eight children. Of these, a girl, when
pleased, at the age of four and a half years, moved her fingers in exactly
the same way, and what is still odder, when much excited, she raised both
her hands, with her fingers still moving, to the sides of her face, in
exactly the same manner as her father had done, and sometimes even still
continued to do so when alone. I never heard of any one, excepting this one
man and his little daughter, who had this strange habit; and certainly
imitation was in this instance out of the question.
Some writers have doubted whether those complex mental attributes, on which
genius and talent depend, are inherited, even when both parents are thus
endowed. But he who will study Mr. Galton's able work on 'Hereditary
Genius' will have its doubts allayed.
Unfortunately it matters not, as far as inheritance is concerned, how
injurious a quality or structure may be if compatible with life. No one can
read the many treatises (12/11. The works which I have read and found most
useful are Dr. Prosper Lucas's great work 'Traite de l'Heredite Naturelle'
1847; Mr. W. Sedgwick in 'British and Foreign Medico-Chirurg. Review' April
and July 1861 and April and July 1863: Dr. Garrod on Gout is quoted in
these articles. Sir Henry Holland 'Medical Notes and Reflections' 3rd
edition 1855. Piorry 'De l'Heredite dans les Maladies' 1840. Adams 'A
Philosophical Treatise on Hereditary Peculiarities' 2nd edition 1815. Essay
on 'Hereditary Diseases' by Dr. J. Steinan 1843. See Paget in 'Medical
Times' 1857 page 192 on the Inheritance of Cancer; Dr. Gould in 'Proc. of
American Acad. of Sciences' November 8, 1853 gives a curious case of
hereditary bleeding in four generations. Harlan 'Medical Researches' page
593.) on hereditary disease and doubt this. The ancients were strongly of
this opinion, or, as Ranchin expresses it, Omnes Graeci, Arabes, et Latini
in eo consentiunt. A long catalogue could be given of all sorts of
inherited malformations and of predisposition to various diseases. With
gout, fifty per cent of the cases observed in hospital practice are,
according to Dr. Garrod, inherited, and a greater percentage in private
practice. Every one knows how often insanity runs in families, and some of
the cases given by Mr. Sedgwick are awful,--as of a surgeon, whose brother,
father, and four paternal uncles were all insane, the latter dying by
suicide; of a Jew, whose father, mother, and six brothers and sisters were
all mad; and in some other cases several members of the same family, during
three or four successive generations, have committed suicide. Striking
instances have been recorded of epilepsy, consumption, asthma, stone in the
bladder, cancer, profuse bleeding from the slightest injuries, of the
mother not giving milk, and of bad parturition being inherited. In this
latter respect I may mention an odd case given by a good observer (12/12.
Marshall quoted by Youatt in his work on 'Cattle' page 284.), in which the
fault lay in the offspring, and not in the mother: in a part of Yorkshire
the farmers continued to select cattle with large hind-quarters, until they
made a strain called "Dutch-buttocked," and "the monstrous size of the
buttocks of the calf was frequently fatal to the cow, and numbers of cows
were annually lost in calving."
[Instead of giving numerous details on various inherited malformations and
diseases, I will confine myself to one organ, that which is the most
complex, delicate, and probably best-known in the human frame, namely, the
eye, with its accessory parts. (12/13. Almost any other organ might have
been selected. For instance Mr. J. Tomes 'System of Dental Surgery' 2nd
edition 1873 page 114 gives many instances with teeth, and others have been
communicated to me.) To begin with the latter: I have received an account
of a family in which one parent and the children are affected by drooping
eyelids, in so peculiar a manner, that they cannot see without throwing
their heads backwards. Mr. Wade, of Wakefield, has given me an analogous
case of a man who had not his eyelids thus affected at birth, nor owed
their state, as far as was known, to inheritance, but they began to droop
whilst he was an infant after suffering from fits, and he has transmitted
the affection to two out of his three children, as was evident in the
photographs of the whole family sent to me together with this account. Sir
A. Carlisle (12/14. 'Philosoph. Transact.' 1814 page 94.) specifies a
pendulous fold to the eyelids, as inherited. "In a family," says Sir H.
Holland (12/15. 'Medical Notes and Reflections' 3rd edition page 33.)
"where the father had a singular elongation of the upper eyelid, seven or
eight children were born with the same deformity; two or three other
children having it not." Many persons, as I hear from Sir J. Paget, have
two or three hairs in their eyebrows much longer than the others; and even
so trifling a peculiarity as this certainly runs in families.
With respect to the eye itself, the highest authority in England, Mr.
Bowman, has been so kind as to give me the following remarks on certain
inherited imperfections. First, hypermetropia, or morbidly long sight: in
this affection, the organ, instead of being spherical, is too flat from
front to back, and is often altogether too small, so that the retina is
brought too forward for the focus of the humours; consequently a convex
glass is required for clear vision of near objects, and frequently even of
distant ones. This state occurs congenitally, or at a very early age, often
in several children of the same family, where one of the parents has
presented it. (12/16. This affection, as I hear from Mr. Bowman, has been
ably described and spoken of as hereditary by Dr. Donders of Utrecht, whose
work was published in English by the Sydenham Society in 1864.) Secondly,
myopia, or short-sight, in which the eye is egg-shaped and too long from
front to back; the retina in this case lies behind the focus, and is
therefore fitted to see distinctly only very near objects. This condition
is not commonly congenital, but comes on in youth, the liability to it
being well known to be transmissible from parent to child. The change from
the spherical to the ovoidal shape seems the immediate consequence of
something like inflammation of the coats, under which they yield, and there
is ground for believing that it may often originate in causes acting on the
individual affected (12/17. M. Giraud-Teulon has recently collected
abundant statistical evidence, 'Revue des Cours Scientifiques' September
1870 page 625, showing that short sight is due to the habit of viewing
objects from a short distance, c'est le travail assidu, de pres.) and may
thenceforward become transmissible. When both parents are myopic Mr. Bowman
has observed the hereditary tendency in this direction to be heightened,
and some of the children to be myopic at an earlier age or in a higher
degree than their parents. Thirdly, squinting is a familiar example of
hereditary transmission: it is frequently a result of such optical defects
as have been above mentioned; but the more primary and uncomplicated forms
of it are also sometimes in a marked degree transmitted in a family.
Fourthly, CATARACT, or opacity of the crystalline lens, is commonly
observed in persons whose parents have been similarly affected, and often
at an earlier age in the children than in the parents. Occasionally more
than one child in a family is thus afflicted, one of whose parents or other
relations, presents the senile form of the complaint. When cataract affects
several members of a family in the same generation, it is often seen to
commence at about the same age in each: e.g., in one family several infants
or young persons may suffer from it; in another, several persons of middle
age. Mr. Bowman also informs me that he has occasionally seen, in several
members of the same family, various defects in either the right or left
eye; and Mr. White Cooper has often seen peculiarities of vision confined
to one eye reappearing in the same eye in the offspring. (12/18. Quoted by
Mr. Herbert Spencer 'Principles of Biology' volume 1 page 244.)
The following cases are taken from an able paper by Mr. W. Sedgwick, and
from Dr. Prosper Lucas. (12/19. 'British and Foreign Medico-Chirurg.
Review' April 1861 pages 482-6; 'L'Hered. Nat.' tome 1 pages 391-408.)
Amaurosis, either congenital or coming on late in life, and causing total
blindness, is often inherited; it has been observed in three successive
generations. Congenital absence of the iris has likewise been transmitted
for three generations, a cleft-iris for four generations, being limited in
this latter case to the males of the family. Opacity of the cornea and
congenital smallness of the eyes have been inherited. Portal records a
curious case, in which a father and two sons were rendered blind, whenever
the head was bent downwards, apparently owing to the crystalline lens, with
its capsule, slipping through an unusually large pupil into the anterior
chamber of the eye. Day-blindness, or imperfect vision under a bright
light, is inherited, as is night-blindness, or an incapacity to see except
under a strong light: a case has been recorded, by M. Cunier, of this
latter defect having affected eighty-five members of the same family during
six generations. The singular incapacity of distinguishing colours, which
has been called DALTONISM, is notoriously hereditary, and has been traced
through five generations, in which it was confined to the female sex.
With respect to the colour of the iris: deficiency of colouring matter is
well known to be hereditary in albinoes. The iris of one eye being of
different colour from that of the other, and the iris being spotted, are
cases which have been inherited. Mr. Sedgwick gives, in addition, on the
authority of Dr. Osborne (12/20. Dr. Osborne, Pres. of Royal College of
Phys. in Ireland, published this case in the 'Dublin Medical Journal' for
1835.), the following curious instance of strong inheritance: a family of
sixteen sons and five daughters all had eyes "resembling in miniature the
markings on the back of a tortoiseshell cat." The mother of this large
family had three sisters and a brother all similarly marked, and they
derived this peculiarity from their mother, who belonged to a family
notorious for transmitting it to their posterity.
Finally, Dr. Lucas emphatically remarks that there is not one single
faculty of the eye which is not subject to anomalies; and not one which is
not subjected to the principle of inheritance. Mr. Bowman agrees with the
general truth of this proposition; which of course does not imply that all
malformations are necessarily inherited; this would not even follow if both
parents were affected by an anomaly which in most cases was transmissible.]
Even if no single fact had been known with respect to the inheritance of
disease and malformations by man, the evidence would have been ample in the
case of the horse. And this might have been expected, as horses breed much
quicker than man, are matched with care, and are highly valued. I have
consulted many works, and the unanimity of the belief by veterinaries of
all nations in the transmission of various morbid tendencies is surprising.
Authors who have had wide experience give in detail many singular cases,
and assert that contracted feet, with the numerous contingent evils, of
ring-bones, curbs, splints, spavin, founder and weakness of the front legs,
roaring or broken and thick wind, melanosis, specific ophthalmia, and
blindness (the great French veterinary Huzard going so far as to say that a
blind race could soon be formed), crib-biting, jibbing and ill-temper, are
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