A History of Science, Volume 4

Part 3 out of 5

been shown that the pancreas, the spleen, the thyroid gland, the
suprarenal capsules are absolutely essential, each in its own
way, to the health of the organism, through metabolic changes
which they alone seem capable of performing; and it is suspected
that various other tissues, including even the muscles
themselves, have somewhat similar metabolic capacities in
addition to their recognized functions. But so extremely
intricate is the chemistry of the substances involved that in no
single case has the exact nature of the metabolisms wrought by
these organs been fully made out. Each is in its way a chemical
laboratory indispensable to the right conduct of the organism,
but the precise nature of its operations remains inscrutable. The
vast importance of the operations of these intermediate organs is
unquestioned.

A consideration of the functions of that other set of organs
known collectively as the nervous system is reserved for a later
chapter.

VI. THEORIES OF ORGANIC EVOLUTION

GOETHE AND THE METAMORPHOSIS OF PARTS

When Coleridge said of Humphry Davy that he might have been the
greatest poet of his time had he not chosen rather to be the
greatest chemist, it is possible that the enthusiasm of the
friend outweighed the caution of the critic. But however that
may be, it is beyond dispute that the man who actually was the
greatest poet of that time might easily have taken the very
highest rank as a scientist had not the muse distracted his
attention. Indeed, despite these distractions, Johann Wolfgang
von Goethe achieved successes in the field of pure science that
would insure permanent recognition for his name had he never
written a stanza of poetry. Such is the versatility that marks
the highest genius.

It was in 1790 that Goethe published the work that laid the
foundations of his scientific reputation--the work on the
Metamorphoses of Plants, in which he advanced the novel doctrine
that all parts of the flower are modified or metamorphosed
leaves.

"Every one who observes the growth of plants, even
superficially," wrote Goethe, "will notice that certain external
parts of them become transformed at times and go over into the
forms of the contiguous parts, now completely, now to a greater
or less degree. Thus, for example, the single flower is
transformed into a double one when, instead of stamens, petals
are developed, which are either exactly like the other petals of
the corolla in form, and color or else still bear visible signs
of their origin.

"When we observe that it is possible for a plant in this way to
take a step backward, we shall give so much the more heed to the
regular course of nature and learn the laws of transformation
according to which she produces one part through another, and
displays the most varying forms through the modification of one
single organ.

"Let us first direct our attention to the plant at the moment
when it develops out of the seed-kernel. The first organs of its
upward growth are known by the name of cotyledons; they have also
been called seed-leaves.

"They often appear shapeless, filled with new matter, and are
just as thick as they are broad. Their vessels are
unrecognizable and are hardly to be distinguished from the mass
of the whole; they bear almost no resemblance to a leaf, and we
could easily be misled into regarding them as special organs.
Occasionally, however, they appear as real leaves, their vessels
are capable of the most minute development, their similarity to
the following leaves does not permit us to take them for special
organs, but we recognize them instead to be the first leaves of
the stalk.

"The cotyledons are mostly double, and there is an observation to
be made here which will appear still more important as we
proceed--that is, that the leaves of the first node are often
paired, even when the following leaves of the stalk stand
alternately upon it. Here we see an approximation and a joining
of parts which nature afterwards separates and places at a
distance from one another. It is still more remarkable when the
cotyledons take the form of many little leaves gathered about an
axis, and the stalk which grows gradually from their midst
produces the following leaves arranged around it singly in a
whorl. This may be observed very exactly in the growth of the
pinus species. Here a corolla of needles forms at the same time a
calyx, and we shall have occasion to remember the present case in
connection with similar phenomena later.

"On the other hand, we observe that even the cotyledons which are
most like a leaf when compared with the following leaves of the
stalk are always more undeveloped or less developed. This is
chiefly noticeable in their margin which is extremely simple and
shows few traces of indentation.

"A few or many of the next following leaves are often already
present in the seed, and lie enclosed between the cotyledons; in
their folded state they are known by the name of plumules. Their
form, as compared with the cotyledons and the following leaves,
varies in different plants. Their chief point of variance,
however, from the cotyledons is that they are flat, delicate, and
formed like real leaves generally. They are wholly green, rest on
a visible node, and can no longer deny their relationship to the
following leaves of the stalk, to which, however, they are
usually still inferior, in so far as that their margin is not
completely developed.

"The further development, however, goes on ceaselessly in the
leaf, from node to node; its midrib is elongated, and more or
less additional ribs stretch out from this towards the sides. The
leaves now appear notched, deeply indented, or composed of
several small leaves, in which last case they seem to form
complete little branches. The date-palm furnishes a striking
example of such a successive transformation of the simplest leaf
form. A midrib is elongated through a succession of several
leaves, the single fan-shaped leaf becomes torn and diverted, and
a very complicated leaf is developed, which rivals a branch in
form.

"The transition to inflorescence takes place more or less
rapidly. In the latter case we usually observe that the leaves of
the stalk loose their different external divisions, and, on the
other hand, spread out more or less in their lower parts where
they are attached to the stalk. If the transition takes place
rapidly, the stalk, suddenly become thinner and more elongated
since the node of the last-developed leaf, shoots up and collects
several leaves around an axis at its end.

"That the petals of the calyx are precisely the same organs which
have hitherto appeared as leaves on the stalk, but now stand
grouped about a common centre in an often very different form,
can, as it seems to me, be most clearly demonstrated. Already in
connection with the cotyledons above, we noticed a similar
working of nature. The first species, while they are developing
out of the seed-kernel, display a radiate crown of unmistakable
needles; and in the first childhood of these plants we see
already indicated that force of nature whereby when they are
older their flowering and fruit-giving state will be produced.

"We see this force of nature, which collects several leaves
around an axis, produce a still closer union and make these
approximated, modified leaves still more unrecognizable by
joining them together either wholly or partially. The
bell-shaped or so-called one-petalled calices represent these
cloudy connected leaves, which, being more or less indented from
above, or divided, plainly show their origin.

"We can observe the transition from the calyx to the corolla in
more than one instance, for, although the color of the calyx is
still usually green, and like the color of the leaves of the
stalk, it nevertheless often varies in one or another of its
parts--at the tips, the margins, the back, or even, the inward
side--while the outer still remains on green.

"The relationship of the corolla to the leaves of the stalk is
shown in more than one way, since on the stalks of some plants
appear leaves which are already more or less colored long before
they approach inflorescence; others are fully colored when near
inflorescence. Nature also goes over at once to the corolla,
sometimes by skipping over the organs of the calyx, and in such a
case we likewise have an opportunity to observe that leaves of
the stalk become transformed into petals. Thus on the stalk of
tulips, for instance, there sometimes appears an almost
completely developed and colored petal. Even more remarkable is
the case when such a leaf, half green and half of it belonging to
the stalk, remains attached to the latter, while another colored
part is raised with the corolla, and the leaf is thus torn in
two.

"The relationship between the petals and stamens is very close.
In some instances nature makes the transition regular--e.g.,
among the Canna and several plants of the same family. A true,
little-modified petal is drawn together on its upper margin, and
produces a pollen sac, while the rest of the petal takes the
place of the stamen. In double flowers we can observe this
transition in all its stages. In several kinds of roses, within
the fully developed and colored petals there appear other ones
which are drawn together in the middle or on the side. This
drawing together is produced by a small weal, which appears as a
more or less complete pollen sac, and in the same proportion the
leaf approaches the simple form of a stamen.

"The pistil in many cases looks almost like a stamen without
anthers, and the relationship between the formation of the two is
much closer than between the other parts. In retrograde fashion
nature often produces cases where the style and stigma (Narben)
become retransformed into petals--that is, the Ranunculus
Asiaticus becomes double by transforming the stigma and style of
the fruit-receptacle into real petals, while the stamens are
often found unchanged immediately behind the corolla.

"In the seed receptacles, in spite of their formation, of their
special object, and of their method of being joined together, we
cannot fail to recognize the leaf form. Thus, for instance, the
pod would be a simple leaf folded and grown together on its
margin; the siliqua would consist of more leaves folded over
another; the compound receptacles would be explained as being
several leaves which, being united above one centre, keep their
inward parts separate and are joined on their margins. We can
convince ourselves of this by actual sight when such composite
capsules fall apart after becoming ripe, because then every part
displays an opened pod."[1]

The theory thus elaborated of the metamorphosis of parts was
presently given greater generality through extension to the
animal kingdom, in the doctrine which Goethe and Oken advanced
independently, that the vertebrate skull is essentially a
modified and developed vertebra. These were conceptions worthy of
a poet--impossible, indeed, for any mind that had not the poetic
faculty of correlation. But in this case the poet's vision was
prophetic of a future view of the most prosaic science. The
doctrine of metamorphosis of parts soon came to be regarded as of
fundamental importance.

But the doctrine had implications that few of its early advocates
realized. If all the parts of a flower--sepal, petal, stamen,
pistil, with their countless deviations of contour and color--are
but modifications of the leaf, such modification implies a
marvellous differentiation and development. To assert that a
stamen is a metamorphosed leaf means, if it means anything, that
in the long sweep of time the leaf has by slow or sudden
gradations changed its character through successive generations,
until the offspring, so to speak, of a true leaf has become a
stamen. But if such a metamorphosis as this is possible--if the
seemingly wide gap between leaf and stamen may be spanned by the
modification of a line of organisms--where does the possibility
of modification of organic type find its bounds? Why may not the
modification of parts go on along devious lines until the remote
descendants of an organism are utterly unlike that organism? Why
may we not thus account for the development of various species of
beings all sprung from one parent stock? That, too, is a poet's
dream; but is it only a dream? Goethe thought not. Out of his
studies of metamorphosis of parts there grew in his mind the
belief that the multitudinous species of plants and animals about
us have been evolved from fewer and fewer earlier parent types,
like twigs of a giant tree drawing their nurture from the same
primal root. It was a bold and revolutionary thought, and the
world regarded it as but the vagary of a poet.

ERASMUS DARWIN

Just at the time when this thought was taking form in Goethe's
brain, the same idea was germinating in the mind of another
philosopher, an Englishman of international fame, Dr. Erasmus
Darwin, who, while he lived, enjoyed the widest popularity as a
poet, the rhymed couplets of his Botanic Garden being quoted
everywhere with admiration. And posterity repudiating the verse
which makes the body of the book, yet grants permanent value to
the book itself, because, forsooth, its copious explanatory
foot-notes furnish an outline of the status of almost every
department of science of the time.

But even though he lacked the highest art of the versifier,
Darwin had, beyond peradventure, the imagination of a poet
coupled with profound scientific knowledge; and it was his poetic
insight, correlating organisms seemingly diverse in structure and
imbuing the lowliest flower with a vital personality, which led
him to suspect that there are no lines of demarcation in nature.
"Can it be," he queries, "that one form of organism has developed
from another; that different species are really but modified
descendants of one parent stock?" The alluring thought nestled
in his mind and was nurtured there, and grew in a fixed belief,
which was given fuller expression in his Zoonomia and in the
posthumous Temple of Nature.

Here is his rendering of the idea as versified in the Temple of
Nature:

"Organic life beneath the shoreless waves
Was born, and nursed in Ocean's pearly caves;
First forms minute, unseen by spheric glass,
Move on the mud, or pierce the watery mass;
These, as successive generations bloom,
New powers acquire and larger limbs assume;
Whence countless groups of vegetation spring,
And breathing realms of fin, and feet, and wing.

"Thus the tall Oak, the giant of the wood,
Which bears Britannia's thunders on the flood;
The Whale, unmeasured monster of the main;
The lordly lion, monarch of the plain;
The eagle, soaring in the realms of air,
Whose eye, undazzled, drinks the solar glare;
Imperious man, who rules the bestial crowd,
Of language, reason, and reflection proud,
With brow erect, who scorns this earthy sod,
And styles himself the image of his God--
Arose from rudiments of form and sense,
An embryon point or microscopic ens!"[2]

Here, clearly enough, is the idea of evolution. But in that day
there was little proof forthcoming of its validity that could
satisfy any one but a poet, and when Erasmus Darwin died, in
1802, the idea of transmutation of species was still but an
unsubstantiated dream.

It was a dream, however, which was not confined to Goethe and
Darwin. Even earlier the idea had come more or less vaguely to
another great dreamer--and worker--of Germany, Immanuel Kant, and
to several great Frenchmen, including De Maillet, Maupertuis,
Robinet, and the famous naturalist Buffon--a man who had the
imagination of a poet, though his message was couched in most
artistic prose. Not long after the middle of the eighteenth
century Buffon had put forward the idea of transmutation of
species, and he reiterated it from time to time from then on till
his death in 1788. But the time was not yet ripe for the idea of
transmutation of species to burst its bonds.

And yet this idea, in a modified or undeveloped form, had taken
strange hold upon the generation that was upon the scene at the
close of the eighteenth century. Vast numbers of hitherto unknown
species of animals had been recently discovered in previously
unexplored regions of the globe, and the wise men were sorely
puzzled to account for the disposal of all of these at the time
of the deluge. It simplified matters greatly to suppose that
many existing species had been developed since the episode of the
ark by modification of the original pairs. The remoter bearings
of such a theory were overlooked for the time, and the idea that
American animals and birds, for example, were modified
descendants of Old-World forms--the jaguar of the leopard, the
puma of the lion, and so on--became a current belief with that
class of humanity who accept almost any statement as true that
harmonizes with their prejudices without realizing its
implications.

Thus it is recorded with eclat that the discovery of the close
proximity of America at the northwest with Asia removes all
difficulties as to the origin of the Occidental faunas and
floras, since Oriental species might easily have found their way
to America on the ice, and have been modified as we find them by
"the well-known influence of climate." And the persons who gave
expression to this idea never dreamed of its real significance.
In truth, here was the doctrine of evolution in a nutshell, and,
because its ultimate bearings were not clear, it seemed the most
natural of doctrines. But most of the persons who advanced it
would have turned from it aghast could they have realized its
import. As it was, however, only here and there a man like Buffon
reasoned far enough to inquire what might be the limits of such
assumed transmutation; and only here and there a Darwin or a
Goethe reached the conviction that there are no limits.

LAMARCK VERSUS CUVIER

And even Goethe and Darwin had scarcely passed beyond that
tentative stage of conviction in which they held the thought of
transmutation of species as an ancillary belief not ready for
full exposition. There was one of their contemporaries, however,
who, holding the same conception, was moved to give it full
explication. This was the friend and disciple of Buffon, Jean
Baptiste de Lamarck. Possessed of the spirit of a poet and
philosopher, this great Frenchman had also the widest range of
technical knowledge, covering the entire field of animate nature.
The first half of his long life was devoted chiefly to botany, in
which he attained high distinction. Then, just at the beginning
of the nineteenth century, he turned to zoology, in particular to
the lower forms of animal life. Studying these lowly organisms,
existing and fossil, he was more and more impressed with the
gradations of form everywhere to be seen; the linking of diverse
families through intermediate ones; and in particular with the
predominance of low types of life in the earlier geological
strata. Called upon constantly to classify the various forms of
life in the course of his systematic writings, he found it more
and more difficult to draw sharp lines of demarcation, and at
last the suspicion long harbored grew into a settled conviction
that there is really no such thing as a species of organism in
nature; that "species" is a figment of the human imagination,
whereas in nature there are only individuals.

That certain sets of individuals are more like one another than
like other sets is of course patent, but this only means, said
Lamarck, that these similar groups have had comparatively recent
common ancestors, while dissimilar sets of beings are more
remotely related in consanguinity. But trace back the lines of
descent far enough, and all will culminate in one original stock.
All forms of life whatsoever are modified descendants of an
original organism. From lowest to highest, then, there is but one
race, one species, just as all the multitudinous branches and
twigs from one root are but one tree. For purposes of convenience
of description, we may divide organisms into orders, families,
genera, species, just as we divide a tree into root, trunk,
branches, twigs, leaves; but in the one case, as in the other,
the division is arbitrary and artificial.

In Philosophie Zoologique (1809), Lamarck first explicitly
formulated his ideas as to the transmutation of species, though
he had outlined them as early as 1801. In this memorable
publication not only did he state his belief more explicitly and
in fuller detail than the idea had been expressed by any
predecessor, but he took another long forward step, carrying him
far beyond all his forerunners except Darwin, in that he made an
attempt to explain the way in which the transmutation of species
had been brought about. The changes have been wrought, he said,
through the unceasing efforts of each organism to meet the needs
imposed upon it by its environment. Constant striving means the
constant use of certain organs. Thus a bird running by the
seashore is constantly tempted to wade deeper and deeper in
pursuit of food; its incessant efforts tend to develop its legs,
in accordance with the observed principle that the use of any
organ tends to strengthen and develop it. But such slightly
increased development of the legs is transmitted to the off
spring of the bird, which in turn develops its already improved
legs by its individual efforts, and transmits the improved
tendency. Generation after generation this is repeated, until the
sum of the infinitesimal variations, all in the same direction,
results in the production of the long-legged wading-bird. In a
similar way, through individual effort and transmitted tendency,
all the diversified organs of all creatures have been
developed--the fin of the fish, the wing of the bird, the hand of
man; nay, more, the fish itself, the bird, the man, even.
Collectively the organs make up the entire organism; and what is
true of the individual organs must be true also of their
ensemble, the living being.

Whatever might be thought of Lamarck's explanation of the cause
of transmutation--which really was that already suggested by
Erasmus Darwin--the idea of the evolution for which he contended
was but the logical extension of the conception that American
animals are the modified and degenerated descendants of European
animals. But people as a rule are little prone to follow ideas to
their logical conclusions, and in this case the conclusions were
so utterly opposed to the proximal bearings of the idea that the
whole thinking world repudiated them with acclaim. The very
persons who had most eagerly accepted the idea of transmutation
of European species into American species, and similar limited
variations through changed environment, because of the relief
thus given the otherwise overcrowded ark, were now foremost in
denouncing such an extension of the doctrine of transmutation as
Lamarck proposed.

And, for that matter, the leaders of the scientific world were
equally antagonistic to the Lamarckian hypothesis. Cuvier in
particular, once the pupil of Lamarck, but now his colleague, and
in authority more than his peer, stood out against the
transmutation doctrine with all his force. He argued for the
absolute fixity of species, bringing to bear the resources of a
mind which, as a mere repository of facts, perhaps never was
excelled. As a final and tangible proof of his position, he
brought forward the bodies of ibises that had been embalmed by
the ancient Egyptians, and showed by comparison that these do not
differ in the slightest particular from the ibises that visit the
Nile to-day.

Cuvier's reasoning has such great historical interest--being the
argument of the greatest opponent of evolution of that day--that
we quote it at some length.

"The following objections," he says, "have already been started
against my conclusions. Why may not the presently existing races
of mammiferous land quadrupeds be mere modifications or varieties
of those ancient races which we now find in the fossil state,
which modifications may have been produced by change of climate
and other local circumstances, and since raised to the present
excessive difference by the operations of similar causes during a
long period of ages?

"This objection may appear strong to those who believe in the
indefinite possibility of change of form in organized bodies, and
think that, during a succession of ages and by alterations of
habitudes, all the species may change into one another, or one of
them give birth to all the rest. Yet to these persons the
following answer may be given from their own system: If the
species have changed by degrees, as they assume, we ought to find
traces of this gradual modification. Thus, between the
palaeotherium and the species of our own day, we should be able
to discover some intermediate forms; and yet no such discovery
has ever been made. Since the bowels of the earth have not
preserved monuments of this strange genealogy, we have no right
to conclude that the ancient and now extinct species were as
permanent in their forms and characters as those which exist at
present; or, at least, that the catastrophe which destroyed them
did not leave sufficient time for the productions of the changes
that are alleged to have taken place.

"In order to reply to those naturalists who acknowledge that the
varieties of animals are restrained by nature within certain
limits, it would be necessary to examine how far these limits
extend. This is a very curious inquiry, and in itself exceedingly
interesting under a variety of relations, but has been hitherto
very little attended to. . . . . . . . .

Wild animals which subsist upon herbage feel the influence of
climate a little more extensively, because there is added to it
the influence of food, both in regard to its abundance and its
quality. Thus the elephants of one forest are larger than those
of another; their tusks also grow somewhat longer in places where
their food may happen to be more favorable for the production of
the substance of ivory. The same may take place in regard to the
horns of stags and reindeer. But let us examine two elephants,
the most dissimilar that can be conceived, we shall not discover
the smallest difference in the number and articulations of the
bones, the structure of the teeth, etc. . . . . . . . .

"Nature appears also to have guarded against the alterations of
species which might proceed from mixture of breeds by influencing
the various species of animals with mutual aversion from one
another. Hence all the cunning and all the force that man is able
to exert is necessary to accomplish such unions, even between
species that have the nearest resemblances. And when the mule
breeds that are thus produced by these forced conjunctions happen
to be fruitful, which is seldom the case, this fecundity never
continues beyond a few generations, and would not probably
proceed so far without a continuance of the same cares which
excited it at first. Thus we never see in a wild state
intermediate productions between the hare and the rabbit, between
the stag and the doe, or between the marten and the weasel. But
the power of man changes this established order, and continues to
produce all these intermixtures of which the various species are
susceptible, but which they would never produce if left to
themselves.

"The degrees of these variations are proportional to the
intensity of the causes that produced them--namely, the slavery
or subjection under which those animals are to man. They do not
proceed far in half-domesticated species. In the cat, for
example, a softer or harsher fur, more brilliant or more varied
colors, greater or less size--these form the whole extent of
variety in the species; the skeleton of the cat of Angora differs
in no regular and constant circumstances from the wild-cat of
Europe. . . . . . . .

The most remarkable effects of the influence of man are produced
upon that animal which he has reduced most completely under
subjection. Dogs have been transported by mankind into every part
of the world and have submitted their action to his entire
direction. Regulated in their unions by the pleasure or caprice
of their masters, the almost endless varieties of dogs differ
from one another in color, in length, and abundance of hair,
which is sometimes entirely wanting; in their natural instincts;
in size, which varies in measure as one to five, mounting in some
instances to more than a hundredfold in bulk; in the form of
their ears, noses, and tails; in the relative length of their
legs; in the progressive development of the brain, in several of
the domesticated varieties occasioning alterations even in the
form of the head, some of them having long, slender muzzles with
a flat forehead, others having short muzzles with a forehead
convex, etc., insomuch that the apparent difference between a
mastiff and a water-spaniel and between a greyhound and a pugdog
are even more striking than between almost any of the wild
species of a genus. . . . . . . .

It follows from these observations that animals have certain
fixed and natural characters which resist the effects of every
kind of influence, whether proceeding from natural causes or
human interference; and we have not the smallest reason to
suspect that time has any more effect on them than climate.

"I am aware that some naturalists lay prodigious stress upon the
thousands which they can call into action by a dash of their
pens. In such matters, however, our only way of judging as to the
effects which may be produced by a long period of time is by
multiplying, as it were, such as are produced by a shorter time.
With this view I have endeavored to collect all the ancient
documents respecting the forms of animals; and there are none
equal to those furnished by the Egyptians, both in regard to
their antiquity and abundance. They have not only left us
representatives of animals, but even their identical bodies
embalmed and preserved in the catacombs.

"I have examined, with the greatest attention, the engraved
figures of quadrupeds and birds brought from Egypt to ancient
Rome, and all these figures, one with another, have a perfect
resemblance to their intended objects, such as they still are
to-day.

"From all these established facts, there does not seem to be the
smallest foundation for supposing that the new genera which I
have discovered or established among extraneous fossils, such as
the paleoetherium, anoplotherium, megalonyx, mastodon,
pterodactylis, etc., have ever been the sources of any of our
present animals, which only differ so far as they are influenced
by time or climate. Even if it should prove true, which I am far
from believing to be the case, that the fossil elephants,
rhinoceroses, elks, and bears do not differ further from the
existing species of the same genera than the present races of
dogs differ among themselves, this would by no means be a
sufficient reason to conclude that they were of the same species;
since the races or varieties of dogs have been influenced by the
trammels of domesticity, which those other animals never did, and
indeed never could, experience."[3]

To Cuvier's argument from the fixity of Egyptian mummified birds
and animals, as above stated, Lamarck replied that this proved
nothing except that the ibis had become perfectly adapted to its
Egyptian surroundings in an early day, historically speaking, and
that the climatic and other conditions of the Nile Valley had not
since then changed. His theory, he alleged, provided for the
stability of species under fixed conditions quite as well as for
transmutation under varying conditions.

But, needless to say, the popular verdict lay with Cuvier; talent
won for the time against genius, and Lamarck was looked upon as
an impious visionary. His faith never wavered, however. He
believed that he had gained a true insight into the processes of
animate nature, and he reiterated his hypotheses over and over,
particularly in the introduction to his Histoire Naturelle des
Animaux sans Vertebres, in 1815, and in his Systeme des
Connaissances Positives de l'Homme, in 1820. He lived on till
1829, respected as a naturalist, but almost unrecognized as a
prophet.

TENTATIVE ADVANCES

While the names of Darwin and Goethe, and in particular that of
Lamarck, must always stand out in high relief in this generation
as the exponents of the idea of transmutation of species, there
are a few others which must not be altogether overlooked in this
connection. Of these the most conspicuous is that of Gottfried
Reinhold Treviranus, a German naturalist physician, professor of
mathematics in the lyceum at Bremen.

It was an interesting coincidence that Treviranus should have
published the first volume of his Biologie, oder Philosophie der
lebenden Natur, in which his views on the transmutation of
species were expounded, in 1802, the same twelvemonth in which
Lamarck's first exposition of the same doctrine appeared in his
Recherches sur l'Organisation des Corps Vivants. It is singular,
too, that Lamarck, in his Hydrogelogie of the same date, should
independently have suggested "biology" as an appropriate word to
express the general science of living things. It is significant
of the tendency of thought of the time that the need of such a
unifying word should have presented itself simultaneously to
independent thinkers in different countries.

That same memorable year, Lorenz Oken, another philosophical
naturalist, professor in the University of Zurich, published the
preliminary outlines of his Philosophie der Natur, which, as
developed through later publications, outlined a theory of
spontaneous generation and of evolution of species. Thus it
appears that this idea was germinating in the minds of several of
the ablest men of the time during the first decade of our
century. But the singular result of their various explications
was to give sudden check to that undercurrent of thought which
for some time had been setting towards this conception. As soon
as it was made clear whither the concession that animals may be
changed by their environment must logically trend, the recoil
from the idea was instantaneous and fervid. Then for a generation
Cuvier was almost absolutely dominant, and his verdict was
generally considered final.

There was, indeed, one naturalist of authority in France who had
the hardihood to stand out against Cuvier and his school, and who
was in a position to gain a hearing, though by no means to divide
the following. This was Etienne Geoffroy Saint-Hilaire, the
famous author of the Philosophie Anatomique, and for many years
the colleague of Lamarck at the Jardin des Plantes. Like Goethe,
Geoffroy was pre-eminently an anatomist, and, like the great
German, he had early been impressed with the resemblances between
the analogous organs of different classes of beings. He
conceived the idea that an absolute unity of type prevails
throughout organic nature as regards each set of organs. Out of
this idea grew his gradually formed belief that similarity of
structure might imply identity of origin--that, in short, one
species of animal might have developed from another.

Geoffroy's grasp of this idea of transmutation was by no means so
complete as that of Lamarck, and he seems never to have fully
determined in his own mind just what might be the limits of such
development of species. Certainly he nowhere includes all organic
creatures in one line of descent, as Lamarck had done;
nevertheless, he held tenaciously to the truth as he saw it, in
open opposition to Cuvier, with whom he held a memorable debate
at the Academy of Sciences in 1830--the debate which so aroused
the interest and enthusiasm of Goethe, but which, in the opinion
of nearly every one else, resulted in crushing defeat for
Geoffrey, and brilliant, seemingly final, victory for the
advocate of special creation and the fixity of species.

With that all ardent controversy over the subject seemed to end,
and for just a quarter of a century to come there was published
but a single argument for transmutation of species which
attracted any general attention whatever. This oasis in a desert
generation was a little book called Vestiges of the Natural
History of Creation, which appeared anonymously in England in
1844, and which passed through numerous editions, and was the
subject of no end of abusive and derisive comment. This book, the
authorship of which remained for forty years a secret, is now
conceded to have been the work of Robert Chambers, the well-known
English author and publisher. The book itself is remarkable as
being an avowed and unequivocal exposition of a general doctrine
of evolution, its view being as radical and comprehensive as that
of Lamarck himself. But it was a resume of earlier efforts rather
than a new departure, to say nothing of its technical
shortcomings, which may best be illustrated by a quotation.

"The whole question," says Chambers, "stands thus: For the
theory of universal order--that is, order as presiding in both
the origin and administration of the world--we have the testimony
of a vast number of facts in nature, and this one in
addition--that whatever is left from the domain of ignorance, and
made undoubted matter of science, forms a new support to the same
doctrine. The opposite view, once predominant, has been
shrinking for ages into lesser space, and now maintains a footing
only in a few departments of nature which happen to be less
liable than others to a clear investigation. The chief of these,
if not almost the only one, is the origin of the organic
kingdoms. So long as this remains obscure, the supernatural will
have a certain hold upon enlightened persons. Should it ever be
cleared up in a way that leaves no doubt of a natural origin of
plants and animals, there must be a complete revolution in the
view which is generally taken of the relation of the Father of
our being.

"This prepares the way for a few remarks on the present state of
opinion with regard to the origin of organic nature. The great
difficulty here is the apparent determinateness of species. These
forms of life being apparently unchangeable, or at least always
showing a tendency to return to the character from which they
have diverged, the idea arises that there can have been no
progression from one to another; each must have taken its special
form, independently of other forms, directly from the appointment
of the Creator. The Edinburgh Review writer says, 'they were
created by the hand of God and adapted to the conditions of the
period.' Now it is, in the first place, not certain that species
constantly maintain a fixed character, for we have seen that what
were long considered as determinate species have been transmuted
into others. Passing, however, from this fact, as it is not
generally received among men of science, there remain some great
difficulties in connection with the idea of special creation.
First we should have to suppose, as pointed out in my former
volume, a most startling diversity of plan in the divine
workings, a great general plan or system of law in the leading
events of world-making, and a plan of minute, nice operation, and
special attention in some of the mere details of the process. The
discrepancy between the two conceptions is surely overpowering,
when we allow ourselves to see the whole matter in a steady and
rational light. There is, also, the striking fact of an
ascertained historical progress of plants and animals in the
order of their organization; marine and cellular plants and
invertebrated animals first, afterwards higher examples of both.
In an arbitrary system we had surely no reason to expect mammals
after reptiles; yet in this order they came. The writer in the
Edinburgh Review speaks of animals as coming in adaptation to
conditions, but this is only true in a limited sense. The groves
which formed the coal-beds might have been a fitting habitation
for reptiles, birds, and mammals, as such groves are at the
present day; yet we see none of the last of these classes and
hardly any traces of the two first at that period of the earth.
Where the iguanodon lived the elephant might have lived, but
there was no elephant at that time. The sea of the Lower Silurian
era was capable of supporting fish, but no fish existed. It
hence forcibly appears that theatres of life must have remained
unserviceable, or in the possession of a tenantry inferior to
what might have enjoyed them, for many ages: there surely would
have been no such waste allowed in a system where Omnipotence was
working upon the plan of minute attention to specialities. The
fact seems to denote that the actual procedure of the peopling of
the earth was one of a natural kind, requiring a long space of
time for its evolution. In this supposition the long existence
of land without land animals, and more particularly without the
noblest classes and orders, is only analogous to the fact, not
nearly enough present to the minds of a civilized people, that to
this day the bulk of the earth is a waste as far as man is
concerned.

"Another startling objection is in the infinite local variation
of organic forms. Did the vegetable and animal kingdoms consist
of a definite number of species adapted to peculiarities of soil
and climate, and universally distributed, the fact would be in
harmony with the idea of special exertion. But the truth is that
various regions exhibit variations altogether without apparent
end or purpose. Professor Henslow enumerates forty-five distinct
flowers or sets of plants upon the surface of the earth,
notwithstanding that many of these would be equally suitable
elsewhere. The animals of different continents are equally
various, few species being the same in any two, though the
general character may conform. The inference at present drawn
from this fact is that there must have been, to use the language
of the Rev. Dr. Pye Smith, 'separate and original creations,
perhaps at different and respectively distinct epochs.' It seems
hardly conceivable that rational men should give an adherence to
such a doctrine when we think of what it involves. In the single
fact that it necessitates a special fiat of the inconceivable
Author of this sand-cloud of worlds to produce the flora of St.
Helena, we read its more than sufficient condemnation. It surely
harmonizes far better with our general ideas of nature to suppose
that, just as all else in this far-spread science was formed on
the laws impressed upon it at first by its Author, so also was
this. An exception presented to us in such a light appears
admissible only when we succeed in forbidding our minds to follow
out those reasoning processes to which, by another law of the
Almighty, they tend, and for which they are adapted."[4]

Such reasoning as this naturally aroused bitter animadversions,
and cannot have been without effect in creating an undercurrent
of thought in opposition to the main trend of opinion of the
time. But the book can hardly be said to have done more than
that. Indeed, some critics have denied it even this merit. After
its publication, as before, the conception of transmutation of
species remained in the popular estimation, both lay and
scientific, an almost forgotten "heresy."

It is true that here and there a scientist of greater or less
repute--as Von Buch, Meckel, and Von Baer in Germany, Bory
Saint-Vincent in France, Wells, Grant, and Matthew in England,
and Leidy in America--had expressed more or less tentative
dissent from the doctrine of special creation and immutability of
species, but their unaggressive suggestions, usually put forward
in obscure publications, and incidentally, were utterly
overlooked and ignored. And so, despite the scientific advances
along many lines at the middle of the century, the idea of the
transmutability of organic races had no such prominence, either
in scientific or unscientific circles, as it had acquired fifty
years before. Special creation held the day, seemingly unopposed.

DARWIN AND THE ORIGIN OF SPECIES

But even at this time the fancied security of the
special-creation hypothesis was by no means real. Though it
seemed so invincible, its real position was that of an apparently
impregnable fortress beneath which, all unbeknown to the
garrison, a powder-mine has been dug and lies ready for
explosion. For already there existed in the secluded work-room of
an English naturalist, a manuscript volume and a portfolio of
notes which might have sufficed, if given publicity, to shatter
the entire structure of the special-creation hypothesis. The
naturalist who, by dint of long and patient effort, had
constructed this powder-mine of facts was Charles Robert Darwin,
grandson of the author of Zoonomia.

As long ago as July 1, 1837, young Darwin, then twenty-eight
years of age, had opened a private journal, in which he purposed
to record all facts that came to him which seemed to have any
bearing on the moot point of the doctrine of transmutation of
species. Four or five years earlier, during the course of that
famous trip around the world with Admiral Fitzroy, as naturalist
to the Beagle, Darwin had made the personal observations which
first tended to shake his belief of the fixity of species. In
South America, in the Pampean formation, he had discovered "great
fossil animals covered with armor like that on the existing
armadillos," and had been struck with this similarity of type
between ancient and existing faunas of the same region. He was
also greatly impressed by the manner in which closely related
species of animals were observed to replace one another as he
proceeded southward over the continent; and "by the
South-American character of most of the productions of the
Galapagos Archipelago, and more especially by the manner in which
they differ slightly on each island of the group, none of the
islands appearing to be very ancient in a geological sense."

At first the full force of these observations did not strike him;
for, under sway of Lyell's geological conceptions, he tentatively
explained the relative absence of life on one of the Galapagos
Islands by suggesting that perhaps no species had been created
since that island arose. But gradually it dawned upon him that
such facts as he had observed "could only be explained on the
supposition that species gradually become modified." From then
on, as he afterwards asserted, the subject haunted him; hence the
journal of 1837.

It will thus be seen that the idea of the variability of species
came to Charles Darwin as an inference from personal observations
in the field, not as a thought borrowed from books. He had, of
course, read the works of his grandfather much earlier in life,
but the arguments of Zoonomia and The Temple of Nature had not
served in the least to weaken his acceptance of the current
belief in fixity of species. Nor had he been more impressed with
the doctrine of Lamarck, so closely similar to that of his
grandfather. Indeed, even after his South-American experience
had aroused him to a new point of view he was still unable to see
anything of value in these earlier attempts at an explanation of
the variation of species. In opening his journal, therefore, he
had no preconceived notion of upholding the views of these or any
other makers of hypotheses, nor at the time had he formulated any
hypothesis of his own. His mind was open and receptive; he was
eager only for facts which might lead him to an understanding of
a problem which seemed utterly obscure. It was something to feel
sure that species have varied; but how have such variations been
brought about?

It was not long before Darwin found a clew which he thought might
lead to the answer he sought. In casting about for facts he had
soon discovered that the most available field for observation lay
among domesticated animals, whose numerous variations within
specific lines are familiar to every one. Thus under
domestication creatures so tangibly different as a mastiff and a
terrier have sprung from a common stock. So have the Shetland
pony, the thoroughbred, and the draught-horse. In short, there is
no domesticated animal that has not developed varieties deviating
more or less widely from the parent stock. Now, how has this been
accomplished? Why, clearly, by the preservation, through
selective breeding, of seemingly accidental variations. Thus one
horseman, by constantly selecting animals that "chance" to have
the right build and stamina, finally develops a race of
running-horses; while another horseman, by selecting a different
series of progenitors, has developed a race of slow, heavy
draught animals.

So far, so good; the preservation of "accidental" variations
through selective breeding is plainly a means by which races may
be developed that are very different from their original parent
form. But this is under man's supervision and direction. By what
process could such selection be brought about among creatures in
a state of nature? Here surely was a puzzle, and one that must be
solved before another step could be taken in this direction.

The key to the solution of this puzzle came into Darwin's mind
through a chance reading of the famous essay on "Population"
which Thomas Robert Malthus had published almost half a century
before. This essay, expositing ideas by no means exclusively
original with Malthus, emphasizes the fact that organisms tend to
increase at a geometrical ratio through successive generations,
and hence would overpopulate the earth if not somehow kept in
check. Cogitating this thought, Darwin gained a new insight into
the processes of nature. He saw that in virtue of this tendency
of each race of beings to overpopulate the earth, the entire
organic world, animal and vegetable, must be in a state of
perpetual carnage and strife, individual against individual,
fighting for sustenance and life.

That idea fully imagined, it becomes plain that a selective
influence is all the time at work in nature, since only a few
individuals, relatively, of each generation can come to maturity,
and these few must, naturally, be those best fitted to battle
with the particular circumstances in the midst of which they are
placed. In other words, the individuals best adapted to their
surroundings will, on the average, be those that grow to maturity
and produce offspring. To these offspring will be transmitted the
favorable peculiarities. Thus these peculiarities will become
permanent, and nature will have accomplished precisely what the
human breeder is seen to accomplish. Grant that organisms in a
state of nature vary, however slightly, one from another (which
is indubitable), and that such variations will be transmitted by
a parent to its offspring (which no one then doubted); grant,
further, that there is incessant strife among the various
organisms, so that only a small proportion can come to
maturity--grant these things, said Darwin, and we have an
explanation of the preservation of variations which leads on to
the transmutation of species themselves.

This wonderful coign of vantage Darwin had reached by 1839. Here
was the full outline of his theory; here were the ideas which
afterwards came to be embalmed in familiar speech in the phrases
"spontaneous variation," and the "survival of the fittest,"
through "natural selection." After such a discovery any ordinary
man would at once have run through the streets of science, so to
speak, screaming "Eureka!" Not so Darwin. He placed the
manuscript outline of his theory in his portfolio, and went on
gathering facts bearing on his discovery. In 1844 he made an
abstract in a manuscript book of the mass of facts by that time
accumulated. He showed it to his friend Hooker, made careful
provision for its publication in the event of his sudden death,
then stored it away in his desk and went ahead with the gathering
of more data. This was the unexploded powder-mine to which I have
just referred.

Twelve years more elapsed--years during which the silent worker
gathered a prodigious mass of facts, answered a multitude of
objections that arose in his own mind, vastly fortified his
theory. All this time the toiler was an invalid, never knowing a
day free from illness and discomfort, obliged to husband his
strength, never able to work more than an hour and a half at a
stretch; yet he accomplished what would have been vast
achievements for half a dozen men of robust health. Two friends
among the eminent scientists of the day knew of his labors--Sir
Joseph Hooker, the botanist, and Sir Charles Lyell, the
geologist. Gradually Hooker had come to be more than half a
convert to Darwin's views. Lyell was still sceptical, yet he
urged Darwin to publish his theory without further delay lest he
be forestalled. At last the patient worker decided to comply with
this advice, and in 1856 he set to work to make another and
fuller abstract of the mass of data he had gathered.

And then a strange thing happened. After Darwin had been at work
on his "abstract" about two years, but before he had published a
line of it, there came to him one day a paper in manuscript, sent
for his approval by a naturalist friend named Alfred Russel
Wallace, who had been for some time at work in the East India
Archipelago. He read the paper, and, to his amazement, found
that it contained an outline of the same theory of "natural
selection" which he himself had originated and for twenty years
had worked upon. Working independently, on opposite sides of the
globe, Darwin and Wallace had hit upon the same explanation of
the cause of transmutation of species. "Were Wallace's paper an
abstract of my unpublished manuscript of 1844," said Darwin, "it
could not better express my ideas."

Here was a dilemma. To publish this paper with no word from
Darwin would give Wallace priority, and wrest from Darwin the
credit of a discovery which he had made years before his
codiscoverer entered the field. Yet, on the other hand, could
Darwin honorably do otherwise than publish his friend's paper and
himself remain silent? It was a complication well calculated to
try a man's soul. Darwin's was equal to the test. Keenly alive
to the delicacy of the position, he placed the whole matter
before his friends Hooker and Lyell, and left the decision as to
a course of action absolutely to them. Needless to say, these
great men did the one thing which insured full justice to all
concerned. They counselled a joint publication, to include on the
one hand Wallace's paper, and on the other an abstract of
Darwin's ideas, in the exact form in which it had been outlined
by the author in a letter to Asa Gray in the previous year--an
abstract which was in Gray's hands before Wallace's paper was in
existence. This joint production, together with a full statement
of the facts of the case, was presented to the Linnaean Society
of London by Hooker and Lyell on the evening of July 1, 1858,
this being, by an odd coincidence, the twenty-first anniversary
of the day on which Darwin had opened his journal to collect
facts bearing on the "species question." Not often before in the
history of science has it happened that a great theory has been
nurtured in its author's brain through infancy and adolescence to
its full legal majority before being sent out into the world.

Thus the fuse that led to the great powder-mine had been lighted.
The explosion itself came more than a year later, in November,
1859, when Darwin, after thirteen months of further effort,
completed the outline of his theory, which was at first begun as
an abstract for the Linnaean Society, but which grew to the size
of an independent volume despite his efforts at condensation, and
which was given that ever-to-be-famous title, The Origin of
Species by Means of Natural Selection, or the Preservation of
Favored Races in the Struggle for Life. And what an explosion it
was! The joint paper of 1858 had made a momentary flare, causing
the hearers, as Hooker said, to "speak of it with bated breath,"
but beyond that it made no sensation. What the result was when
the Origin itself appeared no one of our generation need be told.
The rumble and roar that it made in the intellectual world have
not yet altogether ceased to echo after more than forty years of
reverberation.

NEW CHAMPIONS

To the Origin of Species, then, and to its author, Charles
Darwin, must always be ascribed chief credit for that vast
revolution in the fundamental beliefs of our race which has come
about since 1859, and which made the second half of the century
memorable. But it must not be overlooked that no such sudden
metamorphosis could have been effected had it not been for the
aid of a few notable lieutenants, who rallied to the standards of
the leader immediately after the publication of the Origin.
Darwin had all along felt the utmost confidence in the ultimate
triumph of his ideas. "Our posterity," he declared, in a letter
to Hooker, "will marvel as much about the current belief [in
special creation] as we do about fossil shells having been
thought to be created as we now see them." But he fully realized
that for the present success of his theory of transmutation the
championship of a few leaders of science was all-essential. He
felt that if he could make converts of Hooker and Lyell and of
Thomas Henry Huxley at once, all would be well.

His success in this regard, as in others, exceeded his
expectations. Hooker was an ardent disciple from reading the
proof-sheets before the book was published; Lyell renounced his
former beliefs and fell into line a few months later; while
Huxley, so soon as he had mastered the central idea of natural
selection, marvelled that so simple yet all-potent a thought had
escaped him so long, and then rushed eagerly into the fray,
wielding the keenest dialectic blade that was drawn during the
entire controversy. Then, too, unexpected recruits were found in
Sir John Lubbock and John Tyndall, who carried the war eagerly
into their respective territories; while Herbert Spencer, who had
advocated a doctrine of transmutation on philosophic grounds some
years before Darwin published the key to the mystery--and who
himself had barely escaped independent discovery of that
key--lent his masterful influence to the cause. In America the
famous botanist Asa Gray, who had long been a correspondent of
Darwin's but whose advocacy of the new theory had not been
anticipated, became an ardent propagandist; while in Germany
Ernst Heinrich Haeckel, the youthful but already noted zoologist,
took up the fight with equal enthusiasm.

Against these few doughty champions--with here and there another
of less general renown--was arrayed, at the outset, practically
all Christendom. The interest of the question came home to every
person of intelligence, whatever his calling, and the more deeply
as it became more and more clear how far-reaching are the real
bearings of the doctrine of natural selection. Soon it was seen
that should the doctrine of the survival of the favored races
through the struggle for existence win, there must come with it
as radical a change in man's estimate of his own position as had
come in the day when, through the efforts of Copernicus and
Galileo, the world was dethroned from its supposed central
position in the universe. The whole conservative majority of
mankind recoiled from this necessity with horror. And this
conservative majority included not laymen merely, but a vast
preponderance of the leaders of science also.

With the open-minded minority, on the other hand, the theory of
natural selection made its way by leaps and bounds. Its
delightful simplicity--which at first sight made it seem neither
new nor important--coupled with the marvellous comprehensiveness
of its implications, gave it a hold on the imagination, and
secured it a hearing where other theories of transmutation of
species had been utterly scorned. Men who had found Lamarck's
conception of change through voluntary effort ridiculous, and the
vaporings of the Vestiges altogether despicable, men whose
scientific cautions held them back from Spencer's deductive
argument, took eager hold of that tangible, ever-present
principle of natural selection, and were led on and on to its
goal. Hour by hour the attitude of the thinking world towards
this new principle changed; never before was so great a
revolution wrought so suddenly.

Nor was this merely because "the times were ripe" or "men's minds
prepared for evolution." Darwin himself bears witness that this
was not altogether so. All through the years in which he brooded
this theory he sounded his scientific friends, and could find
among them not one who acknowledged a doctrine of transmutation.
The reaction from the stand-point of Lamarck and Erasmus Darwin
and Goethe had been complete, and when Charles Darwin avowed his
own conviction he expected always to have it met with ridicule or
contempt. In 1857 there was but one man speaking with any large
degree of authority in the world who openly avowed a belief in
transmutation of species--that man being Herbert Spencer. But
the Origin of Species came, as Huxley has said, like a flash in
the darkness, enabling the benighted voyager to see the way. The
score of years during which its author had waited and worked had
been years well spent. Darwin had become, as he himself says, a
veritable Croesus, "overwhelmed with his riches in facts"--facts
of zoology, of selective artificial breeding, of geographical
distribution of animals, of embryology, of paleontology. He had
massed his facts about his theory, condensed them and
recondensed, until his volume of five hundred pages was an
encyclopaedia in scope. During those long years of musing he had
thought out almost every conceivable objection to his theory, and
in his book every such objection was stated with fullest force
and candor, together with such reply as the facts at command
might dictate. It was the force of those twenty years of effort
of a master-mind that made the sudden breach in the
breaswtork{sic} of current thought.

Once this breach was effected the work of conquest went rapidly
on. Day by day squads of the enemy capitulated and struck their
arms. By the time another score of years had passed the doctrine
of evolution had become the working hypothesis of the scientific
world. The revolution had been effected.

And from amid the wreckage of opinion and belief stands forth the
figure of Charles Darwin, calm, imperturbable, serene; scatheless
to ridicule, contumely, abuse; unspoiled by ultimate success;
unsullied alike by the strife and the victory--take him for all
in all, for character, for intellect, for what he was and what he
did, perhaps the most Socratic figure of the century. When, in
1882, he died, friend and foe alike conceded that one of the
greatest sons of men had rested from his labors, and all the
world felt it fitting that the remains of Charles Darwin should
be entombed in Westminster Abbey close beside the honored grave
of Isaac Newton. Nor were there many who would dispute the
justice of Huxley's estimate of his accomplishment: "He found a
great truth trodden under foot. Reviled by bigots, and ridiculed
by all the world, he lived long enough to see it, chiefly by his
own efforts, irrefragably established in science, inseparably
incorporated with the common thoughts of men, and only hated and
feared by those who would revile but dare not."

THE ORIGIN OF THE FITTEST

Wide as are the implications of the great truth which Darwin and
his co-workers established, however, it leaves quite untouched
the problem of the origin of those "favored variations" upon
which it operates. That such variations are due to fixed and
determinate causes no one understood better than Darwin; but in
his original exposition of his doctrine he made no assumption as
to what these causes are. He accepted the observed fact of
variation--as constantly witnessed, for example, in the
differences between parents and offspring--and went ahead from
this assumption.

But as soon as the validity of the principle of natural selection
came to be acknowledged speculators began to search for the
explanation of those variations which, for purposes of argument,
had been provisionally called "spontaneous." Herbert Spencer had
all along dwelt on this phase of the subject, expounding the
Lamarckian conceptions of the direct influence of the environment
(an idea which had especially appealed to Buffon and to Geoffroy
Saint-Hilaire), and of effort in response to environment and
stimulus as modifying the individual organism, and thus supplying
the basis for the operation of natural selection. Haeckel also
became an advocate of this idea, and presently there arose a
so-called school of neo-Lamarckians, which developed particular
strength and prominence in America under the leadership of
Professors A. Hyatt and E. D. Cope.

But just as the tide of opinion was turning strongly in this
direction, an utterly unexpected obstacle appeared in the form of
the theory of Professor August Weismann, put forward in 1883,
which antagonized the Lamarckian conception (though not touching
the Darwinian, of which Weismann is a firm upholder) by denying
that individual variations, however acquired by the mature
organism, are transmissible. The flurry which this denial created
has not yet altogether subsided, but subsequent observations seem
to show that it was quite disproportionate to the real merits of
the case. Notwithstanding Professor Weismann's objections, the
balance of evidence appears to favor the view that the Lamarckian
factor of acquired variations stands as the complement of the
Darwinian factor of natural selection in effecting the
transmutation of species.

Even though this partial explanation of what Professor Cope calls
the "origin of the fittest" be accepted, there still remains one
great life problem which the doctrine of evolution does not
touch. The origin of species, genera, orders, and classes of
beings through endless transmutations is in a sense explained;
but what of the first term of this long series? Whence came that
primordial organism whose transmuted descendants make up the
existing faunas and floras of the globe?

There was a time, soon after the doctrine of evolution gained a
hearing, when the answer to that question seemed to some
scientists of authority to have been given by experiment.
Recurring to a former belief, and repeating some earlier
experiments, the director of the Museum of Natural History at
Rouen, M. F. A. Pouchet, reached the conclusion that organic
beings are spontaneously generated about us constantly, in the
familiar processes of putrefaction, which were known to be due to
the agency of microscopic bacteria. But in 1862 Louis Pasteur
proved that this seeming spontaneous generation is in reality due
to the existence of germs in the air. Notwithstanding the
conclusiveness of these experiments, the claims of Pouchet were
revived in England ten years later by Professor Bastian; but then
the experiments of John Tyndall, fully corroborating the results
of Pasteur, gave a final quietus to the claim of "spontaneous
generation" as hitherto formulated.

There for the moment the matter rests. But the end is not yet.
Fauna and flora are here, and, thanks to Lamarck and Wallace and
Darwin, their development, through the operation of those
"secondary causes" which we call laws of nature, has been
proximally explained. The lowest forms of life have been linked
with the highest in unbroken chains of descent. Meantime,
through the efforts of chemists and biologists, the gap between
the inorganic and the organic worlds, which once seemed almost
infinite, has been constantly narrowed. Already philosophy can
throw a bridge across that gap. But inductive science, which
builds its own bridges, has not yet spanned the chasm, small
though it appear. Until it shall have done so, the bridge of
organic evolution is not quite complete; yet even as it stands
to-day it is perhaps the most stupendous scientific structure of
the nineteenth century.

VII. EIGHTEENTH-CENTURY MEDICINE

THE SYSTEM OF BOERHAAVE

At least two pupils of William Harvey distinguished themselves in
medicine, Giorgio Baglivi (1669-1707), who has been called the
"Italian Sydenham," and Hermann Boerhaave (1668-1738). The work
of Baglivi was hardly begun before his early death removed one of
the most promising of the early eighteenth-century physicians.
Like Boerhaave, he represents a type of skilled, practical
clinitian rather than the abstract scientist. One of his
contributions to medical literature is the first accurate
description of typhoid, or, as he calls it, mesenteric fever.

If for nothing else, Boerhaave must always be remembered as the
teacher of Von Haller, but in his own day he was the widest known
and the most popular teacher in the medical world. He was the
idol of his pupils at Leyden, who flocked to his lectures in such
numbers that it became necessary to "tear down the walls of
Leyden to accommodate them." His fame extended not only all over
Europe but to Asia, North America, and even into South America.
A letter sent him from China was addressed to "Boerhaave in
Europe." His teachings represent the best medical knowledge of
his day, a high standard of morality, and a keen appreciation of
the value of observation; and it was through such teachings
imparted to his pupils and advanced by them, rather than to any
new discoveries, that his name is important in medical history.
His arrangement and classification of the different branches of
medicine are interesting as representing the attitude of the
medical profession towards these various branches at that time.

"In the first place we consider Life; then Health, afterwards
Diseases; and lastly their several Remedies.

"Health the first general branch of Physic in our Institutions is
termed Physiology, or the Animal Oeconomy; demonstrating the
several Parts of the human Body, with their Mechanism and
Actions.

"The second branch of Physic is called Pathology, treating of
Diseases, their Differences, Causes and Effects, or Symptoms; by
which the human Body is known to vary from its healthy state.

"The third part of Physic is termed Semiotica, which shows the
Signs distinguishing between sickness and Health, Diseases and
their Causes in the human Body; it also imports the State and
Degrees of Health and Diseases, and presages their future Events.

"The fourth general branch of Physic is termed Hygiene, or
Prophylaxis.

"The fifth and last part of Physic is called Therapeutica; which
instructs us in the Nature, Preparation and uses of the Materia
Medica; and the methods of applying the same, in order to cure
Diseases and restore lost Health."[1]

From this we may gather that his general view of medicine was not
unlike that taken at the present time.

Boerhaave's doctrines were arranged into a "system" by Friedrich
Hoffmann, of Halle (1660-1742), this system having the merit of
being simple and more easily comprehended than many others. In
this system forces were considered inherent in matter, being
expressed as mechanical movements, and determined by mass,
number, and weight. Similarly, forces express themselves in the
body by movement, contraction, and relaxation, etc., and life
itself is movement, "particularly movement of the heart." Life
and death are, therefore, mechanical phenomena, health is
determined by regularly recurring movements, and disease by
irregularity of them. The body is simply a large hydraulic
machine, controlled by "the aether" or "sensitive soul," and the
chief centre of this soul lies in the medulla.

In the practical application of medicines to diseases Hoffman
used simple remedies, frequently with happy results, for whatever
the medical man's theory may be he seldom has the temerity to
follow it out logically, and use the remedies indicated by his
theory to the exclusion of long-established, although perhaps
purely empirical, remedies. Consequently, many vague theorists
have been excellent practitioners, and Hoffman was one of these.
Some of the remedies he introduced are still in use, notably the
spirits of ether, or "Hoffman's anodyne."

ANIMISTS, VITALISTS, AND ORGANICISTS

Besides Hoffman's system of medicine, there were numerous others
during the eighteenth century, most of which are of no importance
whatever; but three, at least, that came into existence and
disappeared during the century are worthy of fuller notice. One
of these, the Animists, had for its chief exponent Georg Ernst
Stahl of "phlogiston" fame; another, the Vitalists, was
championed by Paul Joseph Barthez (1734-1806); and the third was
the Organicists. This last, while agreeing with the other two
that vital activity cannot be explained by the laws of physics
and chemistry, differed in not believing that life "was due to
some spiritual entity," but rather to the structure of the body
itself.

The Animists taught that the soul performed functions of ordinary
life in man, while the life of lower animals was controlled by
ordinary mechanical principles. Stahl supported this theory
ardently, sometimes violently, at times declaring that there were
"no longer any doctors, only mechanics and chemists." He denied
that chemistry had anything to do with medicine, and, in the
main, discarded anatomy as useless to the medical man. The soul,
he thought, was the source of all vital movement; and the
immediate cause of death was not disease but the direct action of
the soul. When through some lesion, or because the machinery of
the body has become unworkable, as in old age, the soul leaves
the body and death is produced. The soul ordinarily selects the
channels of the circulation, and the contractile parts, as the
route for influencing the body. Hence in fever the pulse is
quickened, due to the increased activity of the soul, and
convulsions and spasmodic movements in disease are due, to the,
same cause. Stagnation of the, blood was supposed to be a
fertile cause of diseases, and such diseases were supposed to
arise mostly from "plethora"--an all-important element in Stahl's
therapeutics. By many this theory is regarded as an attempt on
the part of the pious Stahl to reconcile medicine and theology in
a way satisfactory to both physicians and theologians, but, like
many conciliatory attempts, it was violently opposed by both
doctors and ministers.

A belief in such a theory would lead naturally to simplicity in
therapeutics, and in this respect at least Stahl was consistent.
Since the soul knew more about the body than any physician could
know, Stahl conceived that it would be a hinderance rather than a
help for the physician to interfere with complicated doses of
medicine. As he advanced in age this view of the administration
of drugs grew upon him, until after rejecting quinine, and
finally opium, he at last used only salt and water in treating
his patients. From this last we may judge that his "system," if
not doing much good, was at least doing little harm.

The theory of the Vitalists was closely allied to that of the
Animists, and its most important representative, Paul Joseph
Barthez, was a cultured and eager scientist. After an eventful
and varied career as physician, soldier, editor, lawyer, and
philosopher in turn, he finally returned to the field of
medicine, was made consulting physician by Napoleon in 1802, and
died in Paris four years later.

The theory that he championed was based on the assumption that
there was a "vital principle," the nature of which was unknown,
but which differed from the thinking mind, and was the cause of
the phenomena of life. This "vital principle" differed from the
soul, and was not exhibited in human beings alone, but even in
animals and plants. This force, or whatever it might be called,
was supposed to be present everywhere in the body, and all
diseases were the results of it.

The theory of the Organicists, like that of the Animists and
Vitalists, agreed with the other two that vital activity could
not be explained by the laws of physics and chemistry, but,
unlike them, it held that it was a part of the structure of the
body itself. Naturally the practical physicians were more
attracted by this tangible doctrine than by vague theories "which
converted diseases into unknown derangements of some equally
unknown 'principle.' "

It is perhaps straining a point to include this brief description
of these three schools of medicine in the history of the progress
of the science. But, on the whole, they were negatively at least
prominent factors in directing true progress along its proper
channel, showing what courses were not to be pursued. Some one
has said that science usually stumbles into the right course only
after stumbling into all the wrong ones; and if this be only
partially true, the wrong ones still play a prominent if not a
very creditable part. Thus the medical systems of William Cullen
(1710-1790), and John Brown (1735-1788), while doing little
towards the actual advancement of scientific medicine, played so
conspicuous a part in so wide a field that the "Brunonian system"
at least must be given some little attention.

According to Brown's theory, life, diseases, and methods of cure
are explained by the property of "excitability." All exciting
powers were supposed to be stimulating, the apparent debilitating
effects of some being due to a deficiency in the amount of
stimulus. Thus "the whole phenomena of life, health, as well as
disease, were supposed to consist of stimulus and nothing else."
This theory created a great stir in the medical world, and
partisans and opponents sprang up everywhere. In Italy it was
enthusiastically supported; in England it was strongly opposed;
while in Scotland riots took place between the opposing factions.
Just why this system should have created any stir, either for or
against it, is not now apparent.

Like so many of the other "theorists" of his century, Brown's
practical conclusions deduced from his theory (or perhaps in
spite of it) were generally beneficial to medicine, and some of
them extremely valuable in the treatment of diseases. He first
advocated the modern stimulant, or "feeding treatment" of fevers,
and first recognized the usefulness of animal soups and beef-tea
in certain diseases.

THE SYSTEM OF HAHNEMANN

Just at the close of the century there came into prominence the
school of homoeopathy, which was destined to influence the
practice of medicine very materially and to outlive all the other
eighteenth-century schools. It was founded by Christian Samuel
Friedrich Hahnemann (1755-1843), a most remarkable man, who,
after propounding a theory in his younger days which was at least
as reasonable as most of the existing theories, had the
misfortune to outlive his usefulness and lay his doctrine open to
ridicule by the unreasonable teachings of his dotage,

Hahnemann rejected all the teachings of morbid anatomy and
pathology as useless in practice, and propounded his famous
"similia similibus curantur"--that all diseases were to be cured
by medicine which in health produced symptoms dynamically similar
to the disease under treatment. If a certain medicine produced a
headache when given to a healthy person, then this medicine was
indicated in case of headaches, etc. At the present time such a
theory seems crude enough, but in the latter part of the
eighteenth century almost any theory was as good as the ones
propounded by Animists, Vitalists, and other such schools. It
certainly had the very commendable feature of introducing
simplicity in the use of drugs in place of the complicated
prescriptions then in vogue. Had Hahnemann stopped at this point
he could not have been held up to the indefensible ridicule that
was brought upon him, with considerable justice, by his later
theories. But he lived onto propound his extraordinary theory of
"potentiality"--that medicines gained strength by being
diluted--and his even more extraordinary theory that all chronic
diseases are caused either by the itch, syphilis, or fig-wart
disease, or are brought on by medicines.

At the time that his theory of potentialities was promulgated,
the medical world had gone mad in its administration of huge
doses of compound mixtures of drugs, and any reaction against
this was surely an improvement. In short, no medicine at all was
much better than the heaping doses used in common practice; and
hence one advantage, at least, of Hahnemann's methods. Stated
briefly, his theory was that if a tincture be reduced to
one-fiftieth in strength, and this again reduced to one-fiftieth,
and this process repeated up to thirty such dilutions, the
potency of such a medicine will be increased by each dilution,
Hahnemann himself preferring the weakest, or, as he would call
it, the strongest dilution. The absurdity of such a theory is
apparent when it is understood that long before any drug has been
raised to its thirtieth dilution it has been so reduced in
quantity that it cannot be weighed, measured, or recognized as
being present in the solution at all by any means known to
chemists. It is but just to modern followers of homoeopathy to
say that while most of them advocate small dosage, they do not
necessarily follow the teachings of Hahnemann in this respect,
believing that the theory of the dose "has nothing more to do
with the original law of cure than the psora (itch) theory has;
and that it was one of the later creations of Hahnemann's mind."

Hahnemann's theory that all chronic diseases are derived from
either itch, syphilis, or fig-wart disease is no longer advocated
by his followers, because it is so easily disproved, particularly
in the case of itch. Hahnemann taught that fully three-quarters
of all diseases were caused by "itch struck in," and yet it had
been demonstrated long before his day, and can be demonstrated
any time, that itch is simply a local skin disease caused by a
small parasite.

JENNER AND VACCINATION

All advances in science have a bearing, near or remote, on the
welfare of our race; but it remains to credit to the closing
decade of the eighteenth century a discovery which, in its power
of direct and immediate benefit to humanity, surpasses any other
discovery of this or any previous epoch. Needless to say, I refer
to Jenner's discovery of the method of preventing smallpox by
inoculation with the virus of cow-pox. It detracts nothing from
the merit of this discovery to say that the preventive power of
accidental inoculation had long been rumored among the peasantry
of England. Such vague, unavailing half-knowledge is often the
forerunner of fruitful discovery.

To all intents and purposes Jenner's discovery was original and
unique. Nor, considered as a perfect method, was it in any sense
an accident. It was a triumph of experimental science. The
discoverer was no novice in scientific investigation, but a
trained observer, who had served a long apprenticeship in
scientific observation under no less a scientist than the
celebrated John Hunter. At the age of twenty-one Jenner had gone
to London to pursue his medical studies, and soon after he proved
himself so worthy a pupil that for two years he remained a member
of Hunter's household as his favorite pupil. His taste for
science and natural history soon attracted the attention of Sir
Joseph Banks, who intrusted him with the preparation of the
zoological specimens brought back by Captain Cook's expedition in
1771. He performed this task so well that he was offered the
position of naturalist to the second expedition, but declined it,
preferring to take up the practice of his profession in his
native town of Berkeley.

His many accomplishments and genial personality soon made him a
favorite both as a physician and in society. He was a good
singer, a fair violinist and flute-player, and a very successful
writer of prose and verse. But with all his professional and
social duties he still kept up his scientific investigations,
among other things making some careful observations on the
hibernation of hedgehogs at the instigation of Hunter, the
results of which were laid before the Royal Society. He also
made quite extensive investigations as to the geological
formations and fossils found in his neighborhood.

Even during his student days with Hunter he had been much
interested in the belief, current in the rural districts of
Gloucestershire, of the antagonism between cow-pox and small-pox,
a person having suffered from cow-pox being immuned to small-pox.
At various times Jenner had mentioned the subject to Hunter, and
he was constantly making inquiries of his fellow-practitioners as
to their observations and opinions on the subject. Hunter was too
fully engrossed in other pursuits to give the matter much serious
attention, however, and Jenner's brothers of the profession gave
scant credence to the rumors, although such rumors were common
enough.

At this time the practice of inoculation for preventing
small-pox, or rather averting the severer forms of the disease,
was widely practised. It was customary, when there was a mild
case of the disease, to take some of the virus from the patient
and inoculate persons who had never had the disease, producing a
similar attack in them. Unfortunately there were many objections
to this practice. The inoculated patient frequently developed a
virulent form of the disease and died; or if he recovered, even
after a mild attack, he was likely to be "pitted" and disfigured.
But, perhaps worst of all, a patient so inoculated became the
source of infection to others, and it sometimes happened that
disastrous epidemics were thus brought about. The case was a
most perplexing one, for the awful scourge of small-pox hung
perpetually over the head of every person who had not already
suffered and recovered from it. The practice of inoculation was
introduced into England by Lady Mary Wortley Montague
(1690-1762), who had seen it practised in the East, and who
announced her intention of "introducing it into England in spite
of the doctors."

From the fact that certain persons, usually milkmaids, who had
suffered from cow-pox seemed to be immuned to small-pox, it would
seem a very simple process of deduction to discover that cow-pox
inoculation was the solution of the problem of preventing the
disease. But there was another form of disease which, while
closely resembling cow-pox and quite generally confounded with
it, did not produce immunity. The confusion of these two forms of
the disease had constantly misled investigations as to the
possibility of either of them immunizing against smallpox, and
the confusion of these two diseases for a time led Jenner to
question the possibility of doing so. After careful
investigations, however, he reached the conclusion that there was
a difference in the effects of the two diseases, only one of
which produced immunity from small-pox.

"There is a disease to which the horse, from his state of
domestication, is frequently subject," wrote Jenner, in his
famous paper on vaccination. "The farriers call it the grease.
It is an inflammation and swelling in the heel, accompanied at
its commencement with small cracks or fissures, from which issues
a limpid fluid possessing properties of a very peculiar kind.
This fluid seems capable of generating a disease in the human
body (after it has undergone the modification I shall presently
speak of) which bears so strong a resemblance to small-pox that I
think it highly probable it may be the source of that disease.

"In this dairy country a great number of cows are kept, and the
office of milking is performed indiscriminately by men and maid
servants. One of the former having been appointed to apply
dressings to the heels of a horse affected with the malady I have
mentioned, and not paying due attention to cleanliness,
incautiously bears his part in milking the cows with some
particles of the infectious matter adhering to his fingers. When
this is the case it frequently happens that a disease is
communicated to the cows, and from the cows to the dairy-maids,
which spreads through the farm until most of the cattle and
domestics feel its unpleasant consequences. This disease has
obtained the name of Cow-Pox. It appears on the nipples of the
cows in the form of irregular pustules. At their first appearance
they are commonly of a palish blue, or rather of a color somewhat
approaching to livid, and are surrounded by an inflammation.
These pustules, unless a timely remedy be applied, frequently
degenerate into phagedenic ulcers, which prove extremely
troublesome. The animals become indisposed, and the secretion of
milk is much lessened. Inflamed spots now begin to appear on
different parts of the hands of the domestics employed in
milking, and sometimes on the wrists, which run on to
suppuration, first assuming the appearance of the small
vesications produced by a burn. Most commonly they appear about
the joints of the fingers and at their extremities; but whatever
parts are affected, if the situation will admit the superficial
suppurations put on a circular form with their edges more
elevated than their centre and of a color distinctly approaching
to blue. Absorption takes place, and tumors appear in each
axilla. The system becomes affected, the pulse is quickened;
shiverings, succeeded by heat, general lassitude, and pains about
the loins and limbs, with vomiting, come on. The head is
painful, and the patient is now and then even affected with
delirium. These symptoms, varying in their degrees of violence,
generally continue from one day to three or four, leaving
ulcerated sores about the hands which, from the sensibility of
the parts, are very troublesome and commonly heal slowly,
frequently becoming phagedenic, like those from which they
sprang. During the progress of the disease the lips, nostrils,
eyelids, and other parts of the body are sometimes affected with
sores; but these evidently arise from their being heedlessly
rubbed or scratched by the patient's infected fingers. No
eruptions on the skin have followed the decline of the feverish
symptoms in any instance that has come under my inspection, one
only excepted, and in this case a very few appeared on the arms:
they were very minute, of a vivid red color, and soon died away
without advancing to maturation, so that I cannot determine
whether they had any connection with the preceding symptoms.

"Thus the disease makes its progress from the horse (as I
conceive) to the nipple of the cow, and from the cow to the human
subject.

"Morbid matter of various kinds, when absorbed into the system,
may produce effects in some degree similar; but what renders the
cow-pox virus so extremely singular is that the person that has
been thus affected is forever after secure from the infection of
small-pox, neither exposure to the variolous effluvia nor the
insertion of the matter into the skin producing this
distemper."[2]

In 1796 Jenner made his first inoculation with cowpox matter, and
two months later the same subject was inoculated with small-pox
matter. But, as Jenner had predicted, no attack of small-pox
followed. Although fully convinced by this experiment that the
case was conclusively proven, he continued his investigations,
waiting two years before publishing his discovery. Then,
fortified by indisputable proofs, he gave it to the world. The
immediate effects of his announcement have probably never been
equalled in the history of scientific discovery, unless, perhaps,
in the single instance of the discovery of anaesthesia. In Geneva
and Holland clergymen advocated the practice of vaccination from
their pulpits; in some of the Latin countries religious
processions were formed for receiving vaccination; Jenner's
birthday was celebrated as a feast in Germany; and the first
child vaccinated in Russia was named "Vaccinov" and educated at
public expense. In six years the discovery had penetrated to the
most remote corners of civilization; it had even reached some
savage nations. And in a few years small-pox had fallen from the
position of the most dreaded of all diseases to that of being
practically the only disease for which a sure and easy preventive
was known.

Honors were showered upon Jenner from the Old and the New World,
and even Napoleon, the bitter hater of the English, was among the
others who honored his name. On one occasion Jenner applied to
the Emperor for the release of certain Englishmen detained in
France. The petition was about to be rejected when the name of
the petitioner was mentioned. "Ah," said Napoleon, "we can refuse
nothing to that name!"

It is difficult for us of to-day clearly to conceive the
greatness of Jenner's triumph, for we can only vaguely realize
what a ruthless and ever-present scourge smallpox had been to all
previous generations of men since history began. Despite all
efforts to check it by medication and by direct inoculation, it
swept now and then over the earth as an all-devastating
pestilence, and year by year it claimed one-tenth of all the
beings in Christendom by death as its average quota of victims.
"From small-pox and love but few remain free," ran the old saw. A
pitted face was almost as much a matter of course a hundred years
ago as a smooth one is to-day.

Little wonder, then, that the world gave eager acceptance to
Jenner's discovery. No urging was needed to induce the majority
to give it trial; passengers on a burning ship do not hold aloof
from the life-boats. Rich and poor, high and low, sought succor
in vaccination and blessed the name of their deliverer. Of all
the great names that were before the world in the closing days of
the century, there was perhaps no other one at once so widely
known and so uniformly reverenced as that of the great English
physician Edward Jenner. Surely there was no other one that
should be recalled with greater gratitude by posterity.

VIII. NINETEENTH-CENTURY MEDICINE

PHYSICAL DIAGNOSIS

Although Napoleon Bonaparte, First Consul, was not lacking in
self-appreciation, he probably did not realize that in selecting
a physician for his own needs he was markedly influencing the
progress of medical science as a whole. Yet so strangely are
cause and effect adjusted in human affairs that this simple act
of the First Consul had that very unexpected effect. For the man
chosen was the envoy of a new method in medical practice, and the
fame which came to him through being physician to the First
Consul, and subsequently to the Emperor, enabled him to
promulgate the method in a way otherwise impracticable. Hence the
indirect but telling value to medical science of Napoleon's
selection.

The physician in question was Jean Nicolas de Corvisart. His
novel method was nothing more startling than the now-familiar
procedure of tapping the chest of a patient to elicit sounds
indicative of diseased tissues within. Every one has seen this
done commonly enough in our day, but at the beginning of the
century Corvisart, and perhaps some of his pupils, were probably
the only physicians in the world who resorted to this simple and
useful procedure. Hence Napoleon's surprise when, on calling in
Corvisart, after becoming somewhat dissatisfied with his other
physicians Pinel and Portal, his physical condition was
interrogated in this strange manner. With characteristic
shrewdness Bonaparte saw the utility of the method, and the
physician who thus attempted to substitute scientific method for
guess-work in the diagnosis of disease at once found favor in his
eyes and was installed as his regular medical adviser.

For fifteen years before this Corvisart had practised percussion,
as the chest-tapping method is called, without succeeding in
convincing the profession of its value. The method itself, it
should be added, had not originated with Corvisart, nor did the
French physician for a moment claim it as his own. The true
originator of the practice was the German physician Avenbrugger,
who published a book about it as early as 1761. This book had
even been translated into French, then the language of
international communication everywhere, by Roziere de la
Chassagne, of Montpellier, in 1770; but no one other than
Corvisart appears to have paid any attention to either original
or translation. It was far otherwise, however, when Corvisart
translated Avenbrugger's work anew, with important additions of
his own, in 1808.

"I know very well how little reputation is allotted to translator
and commentators," writes Corvisart, "and I might easily have
elevated myself to the rank of an author if I had elaborated anew
the doctrine of Avenbrugger and published an independent work on
percussion. In this way, however, I should have sacrificed the
name of Avenbrugger to my own vanity, a thing which I am
unwilling to do. It is he, and the beautiful invention which of
right belongs to him, that I desire to recall to life."[1]

By this time a reaction had set in against the metaphysical
methods in medicine that had previously been so alluring; the
scientific spirit of the time was making itself felt in medical
practice; and this, combined with Corvisart's fame, brought the
method of percussion into immediate and well-deserved popularity.
Thus was laid the foundation for the method of so-called physical
diagnosis, which is one of the corner-stones of modern medicine.

The method of physical diagnosis as practised in our day was by
no means completed, however, with the work of Corvisart.
Percussion alone tells much less than half the story that may be
elicited from the organs of the chest by proper interrogation.
The remainder of the story can only be learned by applying the
ear itself to the chest, directly or indirectly. Simple as this
seems, no one thought of practising it for some years after
Corvisart had shown the value of percussion.

Then, in 1815, another Paris physician, Rene Theophile Hyacinthe
Laennec, discovered, almost by accident, that the sound of the
heart-beat could be heard surprisingly through a cylinder of
paper held to the ear and against the patient's chest. Acting on
the hint thus received, Laennec substituted a hollow cylinder of
wood for the paper, and found himself provided with an instrument
through which not merely heart sounds but murmurs of the lungs in
respiration could be heard with almost startling distinctness.

The possibility of associating the varying chest sounds with
diseased conditions of the organs within appealed to the fertile
mind of Laennec as opening new vistas in therapeutics, which he
determined to enter to the fullest extent practicable. His
connection with the hospitals of Paris gave him full opportunity
in this direction, and his labors of the next few years served
not merely to establish the value of the new method as an aid to
diagnosis, but laid the foundation also for the science of morbid
anatomy. In 1819 Laennec published the results of his labors in
a work called Traite d'Auscultation Mediate,[2] a work which
forms one of the landmarks of scientific medicine. By mediate
auscultation is meant, of course, the interrogation of the chest
with the aid of the little instrument already referred to, an
instrument which its originator thought hardly worth naming until
various barbarous appellations were applied to it by others,
after which Laennec decided to call it the stethoscope, a name
which it has ever since retained.

In subsequent years the form of the stethoscope, as usually
employed, was modified and its value augmented by a binauricular
attachment, and in very recent years a further improvement has
been made through application of the principle of the telephone;
but the essentials of auscultation with the stethoscope were
established in much detail by Laennec, and the honor must always
be his of thus taking one of the longest single steps by which
practical medicine has in our century acquired the right to be
considered a rational science. Laennec's efforts cost him his
life, for he died in 1826 of a lung disease acquired in the
course of his hospital practice; but even before this his fame
was universal, and the value of his method had been recognized
all over the world. Not long after, in 1828, yet another French
physician, Piorry, perfected the method of percussion by
introducing the custom of tapping, not the chest directly, but
the finger or a small metal or hard-rubber plate held against the
chest-mediate percussion, in short. This perfected the methods
of physical diagnosis of diseases of the chest in all essentials;
and from that day till this percussion and auscultation have held
an unquestioned place in the regular armamentarium of the
physician.

Coupled with the new method of physical diagnosis in the effort
to substitute knowledge for guess-work came the studies of the
experimental physiologists--in particular, Marshall Hall in
England and Francois Magendie in France; and the joint efforts of
these various workers led presently to the abandonment of those
severe and often irrational depletive methods--blood-letting and
the like--that had previously dominated medical practice. To this
end also the "statistical method," introduced by Louis and his
followers, largely contributed; and by the close of the first
third of our century the idea was gaining ground that the
province of therapeutics is to aid nature in combating disease,
and that this may often be accomplished better by simple means
than by the heroic measures hitherto thought necessary. In a
word, scientific empiricism was beginning to gain a hearing in
medicine as against the metaphysical preconceptions of the
earlier generations.

PARASITIC DISEASES

I have just adverted to the fact that Napoleon Bonaparte, as
First Consul and as Emperor, was the victim of a malady which
caused him to seek the advice of the most distinguished
physicians of Paris. It is a little shocking to modern
sensibilities to read that these physicians, except Corvisart,
diagnosed the distinguished patient's malady as "gale
repercutee"--that is to say, in idiomatic English, the itch
"struck in." It is hardly necessary to say that no physician of
today would make so inconsiderate a diagnosis in the case of a
royal patient. If by any chance a distinguished patient were
afflicted with the itch, the sagacious physician would carefully
hide the fact behind circumlocutions and proceed to eradicate the
disease with all despatch. That the physicians of Napoleon did
otherwise is evidence that at the beginning of the century the
disease in question enjoyed a very different status. At that
time itch, instead of being a most plebeian malady, was, so to
say, a court disease. It enjoyed a circulation, in high circles
and in low, that modern therapeutics has quite denied it; and the
physicians of the time gave it a fictitious added importance by
ascribing to its influence the existence of almost any obscure
malady that came under their observation. Long after Napoleon's
time gale continued to hold this proud distinction. For example,
the imaginative Dr. Hahnemann did not hesitate to affirm, as a
positive maxim, that three-fourths of all the ills that flesh is
heir to were in reality nothing but various forms of "gale
repercutee."

All of which goes to show how easy it may be for a masked
pretender to impose on credulous humanity, for nothing is more
clearly established in modern knowledge than the fact that "gale
repercutee" was simply a name to hide a profound ignorance; no
such disease exists or ever did exist. Gale itself is a
sufficiently tangible reality, to be sure, but it is a purely
local disease of the skin, due to a perfectly definite cause, and
the dire internal conditions formerly ascribed to it have really
no causal connection with it whatever. This definite cause, as
every one nowadays knows, is nothing more or less than a
microscopic insect which has found lodgment on the skin, and has
burrowed and made itself at home there. Kill that insect and the
disease is no more; hence it has come to be an axiom with the
modern physician that the itch is one of the three or four
diseases that he positively is able to cure, and that very
speedily. But it was far otherwise with the physicians of the
first third of our century, because to them the cause of the
disease was an absolute mystery.

It is true that here and there a physician had claimed to find an
insect lodged in the skin of a sufferer from itch, and two or
three times the claim had been made that this was the cause of
the malady, but such views were quite ignored by the general
profession, and in 1833 it was stated in an authoritative medical
treatise that the "cause of gale is absolutely unknown." But
even at this time, as it curiously happened, there were certain
ignorant laymen who had attained to a bit of medical knowledge
that was withheld from the inner circles of the profession. As
the peasantry of England before Jenner had known of the curative
value of cow-pox over small-pox, so the peasant women of Poland
had learned that the annoying skin disease from which they
suffered was caused by an almost invisible insect, and,
furthermore, had acquired the trick of dislodging the pestiferous
little creature with the point of a needle. From them a youth of
the country, F. Renucci by name, learned the open secret. He
conveyed it to Paris when he went there to study medicine, and in
1834 demonstrated it to his master Alibert. This physician, at
first sceptical, soon was convinced, and gave out the discovery
to the medical world with an authority that led to early
acceptance.

Now the importance of all this, in the present connection, is not
at all that it gave the clew to the method of cure of a single
disease. What makes the discovery epochal is the fact that it
dropped a brand-new idea into the medical ranks--an idea
destined, in the long-run, to prove itself a veritable bomb--the
idea, namely, that a minute and quite unsuspected animal parasite
may be the cause of a well-known, widely prevalent, and important
human disease. Of course the full force of this idea could only
be appreciated in the light of later knowledge; but even at the
time of its coming it sufficed to give a great impetus to that
new medical knowledge, based on microscopical studies, which had
but recently been made accessible by the inventions of the
lens-makers. The new knowledge clarified one very turbid medical
pool and pointed the way to the clarification of many others.

Almost at the same time that the Polish medical student was
demonstrating the itch mite in Paris, it chanced, curiously
enough, that another medical student, this time an Englishman,
made an analogous discovery of perhaps even greater importance.
Indeed, this English discovery in its initial stages slightly
antedated the other, for it was in 1833 that the student in
question, James Paget, interne in St. Bartholomew's Hospital,
London, while dissecting the muscular tissues of a human subject,
found little specks of extraneous matter, which, when taken to
the professor of comparative anatomy, Richard Owen, were
ascertained, with the aid of the microscope, to be the cocoon of
a minute and hitherto unknown insect. Owen named the insect
Trichina spiralis. After the discovery was published it
transpired that similar specks had been observed by several
earlier investigators, but no one had previously suspected or, at
any rate, demonstrated their nature. Nor was the full story of
the trichina made out for a long time after Owen's discovery. It
was not till 1847 that the American anatomist Dr. Joseph Leidy
found the cysts of trichina in the tissues of pork; and another
decade or so elapsed after that before German workers, chief
among whom were Leuckart, Virchow, and Zenker, proved that the
parasite gets into the human system through ingestion of infected
pork, and that it causes a definite set of symptoms of disease
which hitherto had been mistaken for rheumatism, typhoid fever,
and other maladies. Then the medical world was agog for a time
over the subject of trichinosis; government inspection of pork
was established in some parts of Germany; American pork was
excluded altogether from France; and the whole subject thus came
prominently to public attention. But important as the trichina
parasite proved on its own account in the end, its greatest
importance, after all, was in the share it played in directing
attention at the time of its discovery in 1833 to the subject of
microscopic parasites in general.

The decade that followed that discovery was a time of great
activity in the study of microscopic organisms and microscopic
tissues, and such men as Ehrenberg and Henle and Bory
Saint-Vincent and Kolliker and Rokitansky and Remak and Dujardin
were widening the bounds of knowledge of this new subject with
details that cannot be more than referred to here. But the
crowning achievement of the period in this direction was the
discovery made by the German, J. L. Schoenlein, in 1839, that a
very common and most distressing disease of the scalp, known as
favus, is really due to the presence and growth on the scalp of a
vegetable organism of microscopic size. Thus it was made clear
that not merely animal but also vegetable organisms of obscure,
microscopic species have causal relations to the diseases with
which mankind is afflicted. This knowledge of the parasites was
another long step in the direction of scientific medical

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