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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

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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 25 of 38)
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structive, that is, adaptational, species-forming or descent-
controlling, influence of natural selection.

The Lamarckian Theory. It is a great presumption to
attempt to offer in so small a book as this any exposition of
a theory so long known and elaborately developed as the ex-
262



OTHER THEORIES OF SPECIES-FORMING. 263

planation of adaptation and species-forming known as La-
marckism. Lamarck l proposed his theory at

Lamarckism.

a time most inopportune; it met with no gen-
eral acceptance, but in later years, post-Darwinian years,
fair-minded biologists have turned back to the books and
papers of this pioneer French exponent of the evolution
principle and have given his theory the careful attention and
scrutiny it deserves but which it failed to get from
Lamarck's contemporaries. This reexamination of the La-
marckian theory or theories has given rise to most radically
divergent opinion and belief concerning its worth : many
biologists account it of great value, others reject it prac-
tically in to to. But this acceptance or rejection depends
almost entirely on one's attitude toward a single funda-
mental part of it, namely, the assumption that variations,
modifications, or characteristics acquired during the life-
time of an individual, these modifications usually being due
to use, disuse, or other functional stimulation of organs and
parts, can be transmitted by this individual to its offspring.
If such newly-acquired, non-inherited characteristics can be
transmitted in full and in detail, or even approximately so,
from the parent to the young, then Lamarckism obviously
offers the simplest of all the explanations so far presented,
of nearly all active and of many passive adaptations. If
such characters cannot be so transmitted, then Lamarckism,
as plausible, as reasonable, as simple and effective as it
seems to be, is practically without validity.

Now this matter of the inheritance of acquired charac-
ters, apparently easily susceptible of definite proof or refuta-
tion by observation and experiment, has been

The inheritance

of acquired char- for years and is to-day one of the burning prob-
acters< lems of biology. There is no general agree-

ment about it, no consensus of authority even. Just at pres-
ent the weight of evidence inclines strongly against such
an inheritance, chiefly because of Weismann's successfully



264 DARWINISM TO-DAY.

destructive criticism of about all the evidence of observa-
tion which has been offered in behalf of it. And yet just at
the present time do biologists recognise more keenly than ever
the need and relief the actuality of such inheritance would
give them in their attempts to solve the great problems of
adaptation and species-forming? I cannot undertake to say
whether more reputable biologists disbelieve in than believe
in the existence of such inheritance, but it is obvious that
the disbelievers have the present prestige of apparent vic-
tory : they call for convincing evidence of such inheritance,
and it is not produced. On the other hand, there are many
reputable, thoughtful, honest, actively working biologists and
palaeontologists (particularly many palaeontologists in pro-
portion to the total number of palaeontological students) who
say, although not loudly and even a bit shamefacedly, per-
haps, that they must believe in the possibility and the actu-
ality of this inheritance ; there is no getting forward with-
out it.

In taking up our brief exposition of Lamarckism, let me
say first that (only in post-Darwinian years has Lamarckism
been put so strongly in contrast with Darwinism as it has.
Darwin himself included part of Lamarckism as a minor
factor or influence in his explanation of adaptation and
species-forming, and Plate, in the recent most notable criti-
cal discussion of Darwinism, takes nearly exactly the old
ground of Darwin, namely, an acceptance of the inheritance,
in some degree and under some conditions, of acquired
characters, and the consequent possibility of a certain
amount of Lamarckian orthogenesis, i. e., an orthogenesis
due to the inheritance of the results of use, disuse, and func-
tional stimuli. It is only neo-Darwinism (of Weismann,
Wallace, and others) and neo-Lamarckism (of Spencer,
Packard, and others) that are so radically opposed, so mutu-
ally exclusive.
(That an animal in its lifetime, and especially during its



OTHER THEORIES OF SPECIES-FORMING. 265

immature life can effect very considerable changes in some
Theconcep- of its body-parts by special use or disuse of

llcordi^ to ti011 these P arts ' or that certain P arts may be modi-
Lamarok. fied through the influence of external stimuli, is

familiar knowledge. Let one recall the increase of the
blacksmith's biceps and inversely the degeneration of un-
used/nuscles, and the thickening or callousing of palms or
other parts of the skin exposed to repeated rough contact.
Bones have ridges developed on them by repeated muscle-
pulls, the hands and eyes can be trained to special functional
skill which involves important although perhaps slight physi-
cal changes, the heart and lungs can be enlarged by special
use ; in short, almost any of the organs of the body, which
are actively used, can be modified either by unusual or extra
use, or by unusual lack of use. Now this use is, in Nature,
almost always of the character of a better aiding in success-
ful living ; that is, it is adaptive use. Animals often chased
by enemies become fleeter by practice ; animals that must
dig for roots or climb trees for leaves and fruits, or dive for
fishes, or leap over obstacles, come by repeated digging, climb-
ing, diving, or leaping to do these things better ; the muscles
and tendons and bones work together better and better,,
become physically modified in accordance with these endeav-
ours. If such betterment of organs and their functions
acquired by individuals could be inherited by their young,
it is obvious that general adaptations of this sort could be
rapidly developed in the course of generations, and new
species, new, that is, because of the adaptive changes thus
effected, be formed. This is the essential thought in-
Lamarck's theory of the method of adaptation and species-
forming. In almost all criticisms of Lamarckism one reads
much contemptuous reference to the expected results of the
organism's "willing" to vary or change in this or that direc-
tion. As a matter of fact the critics of Lamarckism give
that rather absurd feature of alleged Lamarckism much



266 DARWINISM TO-DAY.

more conspicuousness than Lamarck did. He did, indeed,
make some reference to the possible volitional effort of the
organism to change along certain desirable lines, but it is
evident that Lamarck had more in mind the animal's desires
and needs to stretch up higher for leaves or to dig better or
run faster, leading to actual attempts to do these things, than
to any expected results of mere mental wishing or willing.
The essential principle of Lamarckism is an orthogenetic
evolutionary progress toward better and finer adaptation and
adjustment resulting from the inherited effects of actual use,
disuse, and functional stimulation of parts. It is a great
thought and a clear one, and only needs the proof of the
actuality of the inheritance of individually acquired char-
acters to make it one of the principal causal explanations
of adaptation and species change.

However, it is exactly this proof that is wanting. At any
rate, proof of the character and extent necessary to con-

Weismann's V * nCe ^ T CVen a ma J orit y * biologists is

successful attack wanting. The examples or cases brought for-
on amarc ism. war( j by Lamarckians of the alleged inheritance
of mutilations, of the results of disease, and of use and
disuse, are not convincing. It is one of Weismann's posi-
tive contributions to biology to have analysed case after
case of alleged inheritance of acquired characters, and shown
its falseness or at least uncertainty. Many of these cases
he has been able to explain as a result of selection ; others
remain inexplicable; a few, 5 only, are insisted on by the
Lamarckian champions as indisputable examples of such
inheritance. But this very paucity of so-called proved
cases, where there should be thousands of obvious ex-
amples if the principle were really sound, is argument against
Lamarckism.

Our knowledge, too, of the mechanism of heredity makes
strongly against the theory of the inheritance of acquired
characters. Another of Weismann's positive contributions



OTHER THEORIES OF SPECIES-FORMING. 267

to biology is his generally sound distinction between the
germ-plasm and the soma-plasm and parts of the many-
celled body. At maturity the animal body is composed of a
small mass of germ-plasm (germ-cells) situated in the
ovaries or testes, and a great mass of somatic tissues and
organs, all the rest of the body, in fact. Now what is the
condition that exists in the body after a somatic part is
modified by use or disuse or by other functional stimulus, as
when a muscle is enlarged by exercise, the sole of the foot
calloused by going barefoot, an ear more finely attuned by
training? We have a definite physical change in a definite
organ, but is the germ-plasm in any way changed or
affected by this superficial or specific somatic modification,
or if changed is it changed so that it will reproduce in its
future development a similar change in the same organ of
the future new individual ? What possible mechanism have
we in the body to produce or insure such an effect on the
germ-plasm? The answer is obvious and flat; we certainly
know of no such mechanism ; in fact what we do know of
the relation of the germ-cells to the rest of the body makes
any satisfactory conception of such a mechanism as yet
impossible.

Not that certain external conditions may not directly
affect the germ-cells, imbedded and concealed as they are
in the body. Varying conditions of tempera-
te way of ture,* of humidity, and of magnetism, perhaps,
SJitaLerf certaml y anything influencing the food supply
acquired char- and nutrition, can influence the germ-cells at
actors. the same time as it affects all the rest of the

body. But will this influence photograph on these un-
differentiated cells the same picture that it impresses on the

* While temperature may be looked on as an extrinsic influence
affecting germ-cells as well as all other parts of the body, it must be
kept in mind that warm-blooded animals (birds and mammals)
regulate the inner temperature of the body. So changes in external
temperature would but slightly, or not at all, affect the germ-cells.



3 68 DARWINISM TO-DAY.

affected somatic parts. A high temperature or a moist at-
mosphere may modify the colour of the skin, change the pat-
tern of the body superficies, but will overheated germ-cells
produce new individuals showing the same changes of skin
colour and pattern if the same conditions of environment of
the soma are not repeated? How much less conceivable,
then, is the influencing of the germ-cells so as to compel
them to. reproduce on daughter body-parts specific effects
produced on special parental body-parts by such specific and
localised influences as vigorous use of an arm, disuse of a
leg muscle, repeated contact of the palm of the hand with
hard bodies. Indeed, this lack of means of relating the
germ-plasm to the soma, the rest of the body, has stood
much in the way of any satisfactory conception of the phe-
nomena of heredity, that is, the reproduction by the germ-
cells of new individuals resembling the parental, and has
led to constant and thoughtful attention and speculation ever
since the time of Darwin ; indeed, from long before Dar-
win's time.

One of the most favoured ways of attempting to explain
how the germ-cells can represent in their make-up, and
possess the capacity to develop into, the whole complex body,
has been to conceive of the giving off of small representa-
tive particles from all the cells of the body which should be
carried by the blood to the germ-plasm and deposited in the
germ-cells. The germ-cells in their development would
then, by virtue of this manifold representation, be able to
expand into the whole body during a shorter or longer
course of development and growth. This notion of the com-
position of the germ-plasm of micromeres collected from all
the somatic cells, is the conception at the basis of Buffon's
theory of "organic molecules," of Spencer's "physiological
units," Maggi's "plastidules," Altmann's "bioblasts," Wies-
ner's "plasomes," Darwin's "gemmules," Galton's "stirps,"
Nageli's "micellae," Weismann's "biophors and determi-



OTHER THEORIES OF SPECIES-FORMING. 269

nants," and of numerous other micromeric theories. 1 But
the facts of budding, especially as exemplified in plants,
and of regeneration among animals, both of these kinds of
phenomena seeming to show that germ-plasm is not neces-
sarily limited to the germ-cells, strictly so-called, have pre-
vented the acceptance of a too rigorous interpretation of
Weismann's distinction between the germ-plasm and the
soma, and have led to some theories of germ-plasm make-up
and disposition differing from the ones proposing a rigid
restriction of germ-plasm to the germ-cells. The facts that
in many plants any part, as a bit of a twig, say, if cut off, can
reproduce the whole plant just as effectively as a seed
(germ-cell) can, and that many animals can reproduce con-
siderable and complex parts, if lost by accident or self-
mutilation, show that there often resides in somatic cells of
much specialisation the capacity to reproduce not only cells
of their own kind but others of much variety and different
specialisation. So some biologists believe that there is either
a net-work of primitive germ-plasm extending throughout
the soma cells (Nageli's idioplasm theory for example), or
that each somatic cell (at least those with the capacity of
regeneration or reproduction by budding, cuttings, etc.) con-
tains a little primitive germ-plasm stuff besides its own
soma-plasm. And some authors have seen in such theories
of a widely diffused germ-plasm a mechanism for the trans-
mission from the soma to the central germ-cells of the
effects of use, disuse, and functional stimuli derived from
external sources. But does even this conception of a diffuse
and connected germ-plasm, after all, clear up in any way
our difficulty? It makes it easier to see how germ-plasm
may be affected by external and superficial influences, but
does it explain in any degree how these effects can be car-
ried to the germ-cells and so stamped on them as to compel
them to reproduce photographically in their later develop-
ment into new individuals, the specific effects that use, dis-



270 DARWINISM TO-DAY.

use, and external stimuli may have had on specific soma
parts of the parent?

Indeed, Haacke 4 well points out that many or most cases
of apparently direct working of extrinsic influences on the
body are really indirect, in that these influences
do not actuall y directly modify the structure, as
a blacksmith's hammer modifies the shape of a
piece of red-hot iron, or a seal shapes the drop of melted
wax, but that they do it indirectly as stimuli inducing chemi-
cal processes, nervous impulses, etc. The adaptive re-
arrangement of spongy tissue in broken and poorly reset
long bones, apparently a direct reaction, is really only in-
direct, occurring through complex chemical processes, i. e. t
the bringing of special bone-forming materials to certain
places, etc. The outer influences are all stimuli, not actual
sufficient causes or manipulations.

Haacke makes a proposal of much ingenuity, after a keen
andfcsnggtstive discussion of the inheritance of acquired
cKaracters problem, to explain how such an inheritance may
be effected. It is based on the fact that no characters are
directly acquired ; that is, that any change is only the result
of some external stimulus and not of a directly and imme-
diately moulding cause, and that, therefore, in any phenom-
enon of stimulus and effect much more of the body substance
than that composing the exact part or region modified is
influenced. From this Haacke sees the possibility, even the
necessity, of a modification of the whole constitution, includ-
ing the germ-plasm (or perhaps the germ-plasm is modified
as a result of the modification of the whole constitution or
body in which the germ-plasm is being developed and
formed). Thus every acquirement of a new character or
change in an old one must or may affect the germ-plasm.
With regard to passive organs such as the chitin skeletal
parts of insects and crabs, Haacke points out that they are
only the product of active organs, . e., the secreting skin-



OTHER THEORIES OF SPECIES-FORMING. 271

cells, etc. Use and disuse are equivalent simply to much or
little metabolism, and metabolism is as necessary to produce
passive organs or to change them, as use is to make muscles
larger.

However, despite the successful destructive criticism by

Weismann and the neo-Darwinians of the alleged cases of

Many natural- the inheritance of acquired characters adduced

ists believe in by the Lamarckians, and in spite of our lack of

the inheritance " .

ofacqnired knowledge, and indeed, difficulty of conception
characters. o f an y mechanism in the body capable of im-
pressing on the germ-plasm the effects of use, disuse, and
external stimuli in such a way as to compel a photographic
reproduction in the young of these effects as manifest in
the soma of the parent, numerous biologists do not hesitate
to avow their conviction of the actuality of such inheritance.
Now these biologists must have some basis of observation or
scientific fact for their belief. What is this basis ? They rest
their belief largely upon a kind of proof by indirection, a
certain necessity of consequence of other facts, and a logical
argument by elimination. The actual observed status of
animal life to-day and, as revealed by fossils, in past ages,
which is that of the existence of certain lines of descent or
evolution obviously following lines of modification based
on use and disuse ; the inadequacy of natural selection to
explain the cumulation of adaptive modification until such
modification shall have reached a life-and-death determin-
ing selective value ; the apparent impossibility of explaining
the continued degeneration of vestigial organs by natural
selection; the great difficulty of explaining correlative or
coadaptive modifications by selection alone; the possibility
that our lack of knowledge of a mechanism for ensuring the
hereditary transmission of acquired characters may be over-
come with further knowledge of the ultimate structure and
capacity of the germ-plasm ; the great reasonableness and
logical plausibility of the whole Lamarckian conception;



272 DARWINISM TO-DAY.

these and other similarly not wholly convincing reasons are
the sort of not very admirable scientific evidence that the
believers in Lamarckism have to stand on. Two groups of
scientific men are especially well represented among the
Lamarckians: namely, palaeontologists and pathologists.
(Not all palaeontologists and pathologists believe in the
inheritance of acquired characters.) Both of these groups
are familiar with facts that are unfamiliar to biologists gen-
erally. And to my mind it is important that biologists should
recognise the fact that familiarity with the facts of histor-
ical geology on the one hand and with teratogenesis and
human disease on the other, seems to lead to a belief in
Lamarckism.* It should lead the general biologist to be
less positive in his sureness of the invalidity of Lamarckism.
But even were the inheritance of acquired characters now
an established fact, or if it should come to be one, it must
Lamarckism be kept in mind that Lamarckism could be sub-

plahfaLuTapta- st * tutec ^ on ty P artl 7 f r Darwinism. There are
tions. many adaptations and much species-forming

that Lamarckism might explain, but also there are hosts of
adaptations that Lamarckism cannot explain. Plate,' who
defends natural selection but accepts some part of Lamarck-
ism, has pointed this out clearly. He asks how the so-called
"passive adaptations" could be explained by Lamarckism.
"The salivary glands of a non-poisonous snake could pro-
duce ever so much saliva, but it would not become poison-
ous by this, just as little as simple teeth could change by
use to grooved teeth and these to tubular ones. The tusks
of Babirussa could not be led to grow through the skin of
the cheeks through use, for they would have to be actually

* A scientific man representing another phase of biologic activity,
and a man who has enjoyed an extraordinary opportunity for the
observation and testing of modes of inheritance, also believes
strongly in Lamarckism. This is Luther Burbank, the famous Cali-
fornia plant-breeder. For some account * of the scientific aspects of
Burbank's work, see the appendix of this chapter.



OTHER THEORIES OF SPECIES-FORMING. 273

covered by the flesh for awhile in this process, and during
this time be incapable of use. With Fierasfer, the fish that
lives in sea-cucumbers (Holothurians), the anus lies far for-
ward in the throat so that the fish has only to thrust its head
through the anus of the sea-cucumber in order to void its
faeces. How can use of the intestine or its peristaltic move-
ment have produced >such a remarkable change in position
of the anus ?" Plate T offers other similar examples of adap-
tations inexplicable by Lamarckism, and justly says that
hundreds of others could be adduced. He presents suc-
cinctly the possibilities of Lamarckism, the inheritance of
acquired characters being granted, as follows :
Lamarckism could explain

(1) many indifferent characters: example, changes of
temperature produce proportional changes in the
colour-pattern of butterflies' wings;

(2) many simple adaptations of active organs : example,
a muscle becomes stronger through use, and creates
a crest on a bone through pulls ;

(3) some simple adaptations of passive organs (so-called
direct adaptations) : example, in the whales, the
water might directly affect the skin and sub-cutane-
ous tissue and thus produce the loss of hair and the
layer of fat.

Lamarckism could not explain

(i) many characters of active adaptation, even though
of simple kind : example, the penetrating of the lung-
sacs of birds through hair-fine holes into all the
bones ;

<2) many complicated adaptations of active organs : ex-
amples, light-making organs, eyes, smelling-organs,
auditory organs ;

(3) all complicated passive adaptations: example, mim-
icry.

Even if we are ready to admit the possibility or actuality



274 DARWINISM TO-DAY.

of the inheritance of acquired characters in some degree or
under certain conditions and this partial acceptance has;
always seemed to me no more justified than the flat accept-
ance of the principle in its entirety ; it has seemed a weak
sort of attempt at compromise with no real basis in reason
and effecting no advantage in clearing up the problem
there can be no acceptance of the all-sufficiency of Lamarck-
ism as an explanation of adaptation, species-forming, and
descent, any more than there can be such an acceptance of
the all-sufficiency of natural selection. Adaptation and spe-
cies-forming are not, to my mind, one and the same problem :
adaptation can and does lead to species-forming, but species
are formed that are not the results of adaptive modifica-
tion ; whose specific characteristics are indifferent ; that are,
in a word, non-adaptive species. iDe Vries's new species of
evening primroses have a cause not associated with adapta-
tion. Now Lamarckism certainly cannot explain non-
adaptive species any better than selection can. Both selec-
tion and the inheritance of the effects of use, disuse, and
external stimuli are primarily explanations of adaptations
and of adaptive species-forming. Lamarckism is, perhaps,
through its inclusion of the perpetuation of the direct influ-
ence of external stimuli, in better condition to explain non-
adaptive species, but both of these genius-offered explana-
tions of organic evolution need the aid of another or other
factors: the unknown factors of evolution, to speak with
Osborn.

Orthogenesis. One of the principal criticisms of the
natural selection theory is that of the impossibility of ex-
Apparent evi- P lamm S tne beginnings of advantageous modi-
dence for ortho- fication and the beginnings of new organs, by



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 25 of 38)