Vernon L. (Vernon Lyman) Kellogg.

Darwinism to-day; a discussion of present-day scientific criticism of the Darwinian selection theories, together with a brief account of the principal other proposed auxilary and alternative theories of species-forming online

. (page 27 of 38)
Online LibraryVernon L. (Vernon Lyman) KelloggDarwinism to-day; a discussion of present-day scientific criticism of the Darwinian selection theories, together with a brief account of the principal other proposed auxilary and alternative theories of species-forming → online text (page 27 of 38)
Font size
QR-code for this ebook

molecular effects, which he calls physiogenesis, and a me-
chanical influence affecting the organism through molar


effects, for which the term kinetogenesis is retained. The
modifications produced by these two classes of influences
"are supposed to be the result of the action of the causes in
question continued throughout geologic time." These
modifications are assumed to be inherited. In the animal
kingdom kinetogenesis, or the modifying influence of mo-
tion, is assumed to be the more potent efficient cause of
evolution ; in the plant kingdom, physiogenesis. The gen-
eral standpoint of Cope's theory is thus strictly Lamarckian.
But he adds to this reformulation of general Lamarckism a
remarkable feature which he calls archaesthetism. This is-
the doctrine that "animal movements are primitively deter-
mined by sensibility or consciousness" and that this "con-
sciousness has been and is one of the primary factors in the
evolution of animal forms." That is, the kinetogenesis.
which is the chief causo-mechanical factor of the evolution
of the animal kingdom, from primitive single-cell type to
most complex Metazoan, has for its own initiation conscious
effort. Thus Cope is forced to assume, which he does, that
"conscious states have preceded organisms in time and
evolution." The formal statement of this phenomenon,
then, has to be the thesis that energy can be conscious. "If
true," writes Cope, "this is an ultimate fact, neither more
nor less difficult to comprehend than the nature of energy
or matter in their ultimate analyses. But how is such a
hypothesis to be reconciled with the facts of nature, where
consciousness plays a part so infinitesimally small? The
explanation lies close at hand, and has been already referred
to. Energy become automatic is no longer conscious, or is
about to become unconscious." Cope holds then that "con-
sciousness was coincident with the dawn of life," and that
"evolution is essentially a process of mind. The source of
the consciousness, which is back of it, is at present an un-
solved problem."

Cope was a palaeontologist/ 1 and his belief in the necessity


of some factor or factors besides that of natural selection
to explain evolution lines as revealed by palseontological
study is shared by a large majority of the recognised
American palaeontologists. Osborn of Columbia, Williston
of Chicago, Hyatt of Boston, Smith of Stanford, studying
respectively the fossil mammals, the reptiles, and the
molluscs, all voice their belief in the existence of evidence in
the history of the evolution of these animal groups for
orthogenetic variation and descent.

Recently Whitman, the Nestor of American zoologists,
has declared himself strongly as an adherent of the actuality

of orthogenetic evolution. For many years
expression in Whitman has been studying the variations and
favour of ortho- inheritance in pigeons, and through this work

in particular he has become convinced that
species-forming variation does advance in a definite direc-
tion as well as in various directions. He says, 22 "natural
selection, orthogenesis," and mutation appear to present
fundamental contradictions ; but I believe that each stands
for truth, and reconciliation is not distant. The so-called
mutations of (Enothera are indubitable facts ; but two lead-
ing questions remain to be answered. First, are these muta-
tions now appearing, as is agreed, independently of varia-
tion, nevertheless a production of variations that took place
at an earlier period in the history of these plants ? Sec-
ondly, if species can spring into existence at a single leap,
without the assistance of cumulative variations, may they
not also originate with such assistance? That variation
does issue a new species, and that natural selection is a
factor, though not the only factor, in determining results,
is, in my opinion, as certain as that grass grows although
we cannot see it grow. Furthermore, I believe I have
found indubitable evidence of species-forming variation
advancing in a definite direction (orthogenesis), and like-
wise of variations in various directions (amphigenesis). If


I am not mistaken in this, the reconciliation for natural
selection and orthogenesis is at hand" (p. 4).

In the category of determinate or orthogenetic variation
should be included Delage's 2t not very clearly distinguished
Dek e'a the- variation generate. "We call by the name of
oryofgineral general variation," he says, "that which appears
at one time in all the individuals of a race or
at least a large number of individuals and which affects,
most often, several characteristics, if not all, in various
degrees of strength. Variations of this sort must be due
to modifications of the germ plasm produced either by the
reducing division, or by fertilisation, or by accidental altera-
tions which this plasm undergoes in its various divisions."
It is to these variations, according to Delage, that species-
change is due. The inducing influences which result in the
appearance of general variations are use and disuse and the
"conditions of life" (nutrition and climate).

As forming a sort of link between the theories of ortho-
genesis and those of heterogenesis (to be discussed in the
next chapter), may be mentioned the rather
theory of vague and unformed theory of Jaeckel, 25 the

metakinesis. Berlin paleontologist, called "metakinesis."
Jaeckel believes, from a study of fossil animal series, that
there exists evidence of orthogenetic descent, but that while
genera and families may show continuous phyletic series,
species appear sporadically, suddenly, and without special
reference to the phyletic series. He believes that many cases
of epistasis occur: that is, that many sexually mature ani-
mals show arrests of development in early ontogenetic
stages, and have therefore given up a former further
development. He finds numerous examples of this condi-
tion among fossil crinoids and trilobites and living sela-
chians. What his theory of metakinesis really seems to be
is a combination of the sudden, definitive appearance of new
species, which is the essential conception in the theories of


heterogenesis (explained in the next chapter), with the
determinate lines of change or descent, which is the essential
idea in orthogenesis.


1 Lamarck, 1744-1828, the "founder of the complete modern theory
of descent, is the most important figure [in the history of the

References to theory of evolution] between Aristotle and Darwin"
Lamarck's (Osborn, "From the Greeks to Darwin," p. 156, 1899).

writings. jjis tneor y o f descent and the causes of descent was

presented in his "Philosophic Zoologique," a large work published in
1809. For a brief account of Lamarck's life and work, see Osborn,
"From the Greeks to Darwin," pp. 156-181, 1899. For an exhaustive
account with full quotations from Lamarck's exposition of his the-
ories, see Packard, "Lamarck, His Life and Work," 1901. For ex-
positions of the Lamarckian point of view compared with the Dar-
winian position, see Haeckel, E., "Die Naturanschauung von Darwin,
Goethe, und Lamarck," 1882; Lang, A., "Zur Characteristik der For-
schungswege von Lamarck und Darwin," 1889; Ward, L. F., "Neo-
Darwinism and Neo-Lamarckism," Proc. Biol. Soc., Wash., Vol. VI,
pp. 11-71, 1891; Hutton, F. W., "Darwinism and Lamarckism, Old
and New," 1899; Pauly, A., "Darwinismus und Lamarckismus," 1905.

2 Among the more conspicuous of these cases are Brown-Sequard's
epileptic guinea-pigs, Hyatt's Planorbis shells, Cunningham's flat-

Brown-Se"- fishes, and Fischer's butterflies. Morgan, in "Evo-
qnard'B experi- lution and Adaptation," gives the following account
ments on guinea- and discussion of the Brown-Sequard experiments
and results : "The best direct evidence in favour of the
Lamarckian argument is that furnished by the experiments of Brown-
Sequard. He found, as the result of injury to the nervous system of
guinea-pigs, that epilepsy appeared in the adult animal, and that young
born from these epileptic parents became also epileptic. Still more
important was his discovery that, after an operation on the nerves,
as a result of which certain organs, the ear or the leg, for instance,
are affected, the same affection appears in the young born from
such parents. These results of Brown-Sequard have been vouched
for by two of his assistants, and his results in regard to the inheri-
tance of epilepsy have been confirmed by Obersteiner, and by
Luciani on dogs. Equally important is their later confirmation, as
far as the main facts go, by Romanes.

"Brown-Sequard gives the following summary of his results.
I follow Romanes' translation in his book on 'Darwin and After


Darwin/ where there is also given a careful analysis of Brown-
Sequard's results, as well as the outcome of the experiments of
Romanes himself. The summary is as follows :

"i. 'Appearance of epilepsy in animals born of parents which had
been rendered epileptic by an injury to the spinal-cord.

"2. 'Appearance of epilepsy also in animals born of parents
which had been rendered epileptic by section of the sciatic nerve.

"3. 'A change in the shape of the ear in animals born of parents
in which such a change was the effect of a division of the cervical
sympathetic nerve.

"4. 'Partial closure of the eyelids in animals born of parents in
which that state of the eyelids had been caused either by section
of the cervical sympathetic nerve, or the removal of the superior
cervical ganglion.

"5. 'Exophthalmia in animals born of parents in which an injury
to the restiform body had produced that protrusion of the eyeball.
This interesting fact .1 have witnessed a good many times, and seen
the transmission of the morbid state of the eye continue through
four generations. In these animals modified by heredity, the two
eyes generally protruded, although of the parents usually only one
showed exophthalmia, the lesion having been made in most cases
only on one of the corpora restiformia.

"6. 'Haematoma and dry gangrene of the ears in animals born
of parents in which these ear alterations had been caused by an
injury to the restiform body near the nib of the calamus.

"7. 'Absence of two toes out of the three of the hind-leg, and
sometimes of the three, in animals whose parents had eaten up
their hind-leg toes, which had become anaesthetic from a section
of the sciatic nerve alone, or of that nerve and also of the crural.
Sometimes, instead of complete absence of the toes, only a part
of one or two or three was missing in the young, although in
the parent not only the toes, but the whole foot was absent
(partly eaten off, partly destroyed by inflammation, ulceration, or

"8. 'Appearance of various morbid states of the skin and hair
of the neck and face in animals born of parents having had similar
alterations in the same parts as effects of an injury to the sciatic

"Romanes, who later went over the same ground, in part under
the immediate direction of Brown-Sequard himself, has made some
important observations in regard to these results, many of which
he was able to confirm.

"He did not repeat the experiment of cutting the cord, but he
found that, to produce epilepsy, it was only necessary to cut the


sciatic nerve. The 'epileptiform habit' does not appear in the animal
until some time after the operation; it lasts for some weeks or
months, and then disappears. The attacks are not brought on spon-
taneously, but by 'irritating a small area of the skin behind the
ear on the same side of the body as that on which the sciatic nerve
had been divided.' The attack lasts for only a few minutes, and
during it the animal is convulsed and unconscious. Romanes thinks
that the injury to the sciatic nerve, or to the spinal cord, produces
some sort of a change in the cerebral centres, 'and that it is this
change whatever it is, and in whatever part of the brain it takes
place which causes the remarkable phenomena in question.'

"In regard to Brown-Sequard's statements, made in the 3d and
the 4th paragraphs, in respect to the results of the operation of
cutting the cervical sympathetic, Romanes had not confirmed the
results when his manuscript went to press; but soon afterward,
after Romanes' death, a note was printed in Nature, by Dr. Hill,
announcing that two guinea-pigs from Romanes' experiment had
been born, 'both of which exhibited a well-marked droop of the
upper eyelid. These guinea-pigs were the offspring of a male and
feimle in both of which I had produced for Dr. Romanes, some
months earlier, a droop of the left upper eyelid by division of the left
cervical sympathetic nerve. This result is a corroboration of the
series of Brown-Sequard experiments on the inheritance of acquired

"Romanes states that he also found that injury to a particular
spot of the restiform bodies is quickly followed by a protrusion
of the eye on the same side, and further, that he had 'also had
many cases in which some of the progeny of parents thus affected
have shown considerable protrusion of the eyeballs of both sides,
and this seemingly abnormal protrusion has occasionally been
transmitted to the next generation. Nevertheless, I am far from
satisfied that this latter fact is anything more than an accidental
coincidence.' This reservation is made on the ground that the
protrusion in the young is never so great as in the parents, and
also because there is amongst guinea-pigs a considerable amount
of individual variation in the degree of prominence of the eye-
balls. Romanes, while unwilling to deny that an 'obviously abnor-
mal amount of protrusion, due to the operation, may be inherited
in lesser degree,' is also unwilling to affirm so important a conclu-
sion on the basis of these experiments alone.

"In regard to Brown-Sequard's 6th statement, Romanes found
after injury to the restiform body that hsematoma and dry gan-
grene may supervene, either several weeks after the operation, or
at any subsequent time, even many months afterward. The disease


usually affects the upper parts of both ears, and may then gradually
extend downward until nearly the whole ear is involved. 'As re-
gards the progeny of animals thus affected in some cases, but by
no means in all, a similarly morbid state of the ears may arise
apparently at any time in the life history of the individual. But
I have observed that in cases where two or more individuals of the
same litter develop this diseased condition, they usually do so at
about the same time, even though this may be months after birth,
and therefore after the animals are fully grown.' Moreover, the
morbid process never extends so far in the young as it does in the
parents, and 'it almost always affects the middle third of the ear.'
Several of the progeny from this first generation, which had appa-
rently inherited the disease, but had not themselves been directly
operated upon, showed a portion of the ear consumed apparently
by the same disease. Romanes then gives the following signifi-
cant analysis of this result. Since a different part of the ear
of the progeny is affected, and also a 'very much less quantity
thereof, it might seem that the result was due either to a mere
coincidence, or to the transmission of microbes. But he goes on
to say, that he fairly well excluded both of these possibilities, for,
in the first place, he has never observed 'the very peculiar process
in the ears, or in any other parts of guinea-pigs which have neither
themselves had the restiform bodies injured, nor been born of
parents thus mutilated.' In regard to microbes. Romanes tried to
infect the ears of normal guinea-pigs by first scarifying these parts,
and then rubbing them with the diseased surfaces of the ears of
affected guinea-pigs. In not a single case was the disease produced.

''Romanes concludes that these 'results in large measure corrobo-
rate the statements of Brown-Sequard; and it is only fair to add
that he told me they were the results which he had himself obtained
most frequently, but that he had also met with many cases where the
diseased condition of the ears in parents affected the same parts in
their progeny and also occurred in more equal degrees.'

"We come now to the remarkable conclusion given in Brown-
Sequard' s 7th statement, in regard to the absence of toes in animals
whose parents had eaten off their own hind toes and even parts
of their legs. Romanes got neuroses in the animals operated upon,
and found that the toes might be eaten off; but none of the young
showed any defect in these parts. Furthermore, Romanes repeated
the same operation upon the descendants through six successive
generations, so as to produce, if possible, a cumulative effect, but no
inheritance of the mutilation was observed. 'On the other hand,
Brown-Sequard informed me that he had observed this inherited
absence of toes only in about one or two per cent, of cases.' It is


possible, therefore, Romanes adds, that his own experiments were
not sufficiently numerous to have obtained such cases.

"In this connection I may give an account of some observa-
tions that I made while carrying out some experiments in telegony
with mice. I found in one litter of mice that when the young came
out of the nest they were tailless. The same thing happened again
when the second litter was produced, but this time I made my
observation sooner, and examined the young mice immediately after
birth. I found that the mother had bitten off, and presumably
eaten, the tails of her offspring at the time of birth. Had I been
carrying on a series of experiments to see if, when the tails of the
parents were cut off, the young inherit the defect, I might have
been led into the error of supposing that I had found such a case in
these mice. If this idiosyncrasy of the mother had reappeared in
any of her descendants, the tails might have disappeared in suc-
ceeding generations. This perversion of the maternal instincts is
not difficult to understand, when we recall that the female mouse
bites off the navel-string of each of her young as they are born,
and at the same time eats the afterbirth. Her instinct was carried
further in this case, and the projecting tail was also removed. ,

"Is it not possible that something of this sort took place in
Brown-Sequard's experiment? The fact that the adults had eaten
off their own feet might be brought forward to indicate the possi-
bility of a perverted instinct in this case also. At least my obser-
vation shows a possible source of error that must be guarded
against in future work on this subject.

"In regard to the 8th statement of Brown-Sequard, as to various
morbid states of the skin, Romanes did not test this, because the
facts which it alleges did not seem of a sufficiently definite character.

"These experiments of Brown-Sequard, and of those who have
repeated them, may appear to give a brilliant experimental confirma-
tion of the Lamarckian position ; yet I think, if I were a Lamarckian,
I should feel very uncomfortable to have the best evidence in sup-
port of the theory come from this source, because there are a
number of facts in the results that make them appear as though
they might, after all, be the outcome of a transmitted disease, as
Weismann claims, rather than the inheritance of an acquired char-
acter. Until we know more of the pathology of epilepsy, it may
be well not to lay too great emphasis on these experiments. It
should not be overlooked that during the long time that the embryo
is nourished in the uterus of the mother, there is ample opportu-
nity given for the transmission of material, or possibly even of
bacteria. If it should prove true that epilepsy is due to some sub-
stance present in the nervous system, such substances could get


there during the uterine life of the embryo. Even if this were the
case, it may be claimed that it does not give an explanation of the
local reappearance of the disease in the offspring. But here, also,
we must be on our guard, for it is possible that only certain regions
of the body are susceptible to a given disease; and it has by no
means been shown that the local defect itself is inherited, but only
the disease. Romanes insists that a very special operation is neces-
sary to bring about certain forms of transmission."

The case of the Planorbis shells studied by Hyatt (Proc. Amer.
Phil. Soc., Vol. XXXII, p. 615 ff.) has been interestingly dis-

Hyatt's studies cussed by Le Dantec ("Traite de Biologic," pp. 296
of Planorbis. ff., 1903) as follows: "On trouve, dans les terrains
tres anciens, des coquilles de Cephalopodes qui ont la forme d'une
come de vache et dont la section transversale est a peu pres circu-
laire; en suivant la serie des fossiles de cette categoric dans
des terrains plus recents, on constate que ces coquilles, presque
droites naguere, se sont enroulees de plus en plus a la maniere
d'une spirale d' Archimede ; nous ne connaissons pas la raison
de cette transformation, mais la presence de certains caracteres
communs permet de considerer comme demontre que les formes
enroulees descendent des animaux a coquilles droites. Or, 1'enroule-
ment est tellement fort dans certains types que les tours de
spire successifs s'impriment les uns dans les autres, donnant nais-
sance a un sillon dorsal dont la genese mecanique est evidente,
puisqu'il resulte sans conteste de la pression du tour de spire
precedent sur le suivant.

"Tant que les animaux en question restent aussi nettement
enroules, on peut admettre que ce caractere de 1'existence d'un sillon
dorsal est acquis individuellement par chaque Cephalopode pour des
raisons mecaniques evidentes, le contact des tours de spires.

"Mais voila qu'a une periode plus recente de 1'histoire du monde,
les decouvertes paleontologiques nous ( montrent que les descendants
de ces Cephalopodes a coquille enroulee ont subi un commencement
de deroulement et ont maintenant la forme d'une spirale d'Archi-
mede a tours de spires plus ecartes les uns des autres et ne se
touchant plus ; et notez bien que des caracteres communs permettent
d'affirmer que ces Cephalopodes a moitie deroules descendent de
ceux dont 1'enroulement etait beaucoup plus serre.

"Or, chose admirable, le sillon dorsal persiste chez ces etres a
coque a moitie deroulee ! Cependant il n'y a plus maintenant
pression d'un tour de spire sur le tour de spire precedent; nous
avons compris mecaniquement la genese de ce sillon dorsal, quand
les tours de spire se touchaient et se pressaient 1'un 1'autre; et ce
sillon persiste en dehors des conditions mecaniques ou il a etc


cl'abord produit; il se transmet a des descendants dont la coquille
est deroulee! C'est done que le patrimoine hereditaire a cte
modifie sous I' influence de la production mecanique de ce sillon
dorsal, au point de devenir adequat a cette forme nouvelle d'equi-
libre; il y a un nouveau patrimoine hereditaire, qui construisant un
individu nouveau et son squelette, fera apparaitre, sans pression,
le sillon dorsal!"

The results of the experiments of Cunningham on flatfishes are
stated by the author, in a paper on "The Problem of Variation,"
Nat. Sci., Vol. Ill, p. 285, 1893. Cunningham put the very young^
fish, while still bilaterally symmetrical (in which stage the pigment
is equally developed on both sides of the body), into aquaria lighted
from below. He found that when the young fish begins to undergo
its metamorphosis, the pigment gradually disappears on one side,
as it would have done under normal conditions, i. e., when they are
lighted from above. If, however, the fish are kept for a short time
longer, lighted from below, the pigment begins to come back again.
"The first fact," says Cunningham, "proves that the disappearance
of the pigment-cells from the lower side in the metamorphosis is a
hereditary character, and not a change produced in each individual
by the withdrawal of the lower side from the action of the light.
On the other hand, the experiments show that the absence of pig-
ment-cells from the lower side throughout life is due to the fact that
light does not act upon that side, for, when it is allowed to act,,
pigment-cells appear. It seems to me that the only reasonable con-
clusion from these facts is that the disappearance of the pigment-

Online LibraryVernon L. (Vernon Lyman) KelloggDarwinism to-day; a discussion of present-day scientific criticism of the Darwinian selection theories, together with a brief account of the principal other proposed auxilary and alternative theories of species-forming → online text (page 27 of 38)