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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 13 of 38)
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With certain concessions made, what use of further struggle
over them ? Thus by answering briefly the insignificant and
undamaging part of anti-Darwinian attack, or by referring
to Darwin's own answers of this, and by indicating clearly
and definitely the concessions that Darwinism is ready to
make, has made, indeed these humiliating concessions, if
humiliation is in them, only being made necessary because

*Darwin's anticipation of the criticisms of his theories, and his
own open-minded and detailed answers to these criticisms, should,
of course, be held clearly in mind by any student of fiir-und-
gcgen Darwinismus. but many of these answers concern objections
which present-day Darwinism has largely conceded as valid, and
most of the others touch matters on which modern biological re-
search has thrown much new light. So that it is perhaps fairer
to the Darwinian theories to set out the attitude of present-day
Darwinians. For a detailed critical consideration of Darwin's own
answers, see Morgan, "Evolution and Adaptation" (1903).
129



,30 DARWINISM TO-DAY.

of the ill judgment and rash enthusiasm of certain too
ardent and too conspicuous friends of Darwinism, the so-
called neo-Darwinians with this salutary restriction of
diffuseness in account, "Darwinism Defended" may be con-
fined to fewer pages than have been devoted to "Darwinism
Attacked" without suggesting by this brevity any necessary
weakness in the Darwinian position.

Let us give our first attention to the Darwinian conces-
sions those concessions which the biological world has

Beaction practically agreed have been made necessary by
against ultra- the steady criticism of the exaggeration and
Darwinism. magnification, almost wholly post-Darwinian in
appearance, of the Darwinian factors in evolution. It is
strange, but wholly true, that the modern reaction and revolt
against Darwinism is chiefly due to the activity and attitude
taken by certain of its over-ardent friends. Weismann, by
denying validity to any other evolutionary factor than the
natural selection of purely congenital variations, and by the
development to an illogical and untenable extreme of his
theory of the independence and continuity of the germ-
plasm, precipitated the revolt and furnished the enemy with
the very weapons needed to overcome neo-Darwinism.
The evolution champion Haeckel, although not at all a
Weismannian Darwinian, has also by his daring and reck-
less speculative development of certain phases of evolution-
ary thought, especially in its relation to sociology and
religious philosophy, and by his obstinate adherence to, and
reiteration of, certain long discredited more strictly biological

Haeckel dogmas of evolutionary science, contributed to
produce an irritation and antagonistic activity
among biologists, especially in Germany, which has helped
make many friends for the anti-Darwinian party. "Der
Haeckelismus in der Zoologie," ' as Semper originally
phrased it, is the object of a curiously bitter and often-
expressed contempt in German biological circles. I fancy



DARWINISM -DEFENDED. 131

that this feeling really depends not so much on Haeckel's
attitude and speculative writing in zoology as in his unpar-
donable intrusion into politics and religion ; the Social-
Democrats and the Free-Thinkers have found a helpful and
willing scientific champion in Haeckel. And this is sin
superlative in rigorous minds ! As a matter of fact, how-
>ever, biologists generally are agreed that Haeckel's daring
speculations and reckless progress in advance of positions
grounded on observed fact have been, in a way, always repre-
hensible and dangerous to the fair fame of biological science.
But, to my mind, biologists may also fairly agree that this
very activity and speculative daring of Haeckel have in-
spired much genuine biological investigation (for the sake
of denying or confirming his speculations) and have led to
a salutary reactionary critical attitude toward other biologi-
cal speculations and hypotheses. It is a rare ism in any
science or philosophy that yields nothing good.

Weismannism is wholly different from Haeckelism. It
has only in common with it that it is, in part, also daringly
speculative. But the speculations primarily interest neither
Free-Thinkers nor Social-Democrats. They have to do
with the ultimate structure and behaviour of protoplasm,
especially germinal protoplasm, and with the intimate proc-
' esses of heredity and variation.

Weismann first attempted to free Darwin's general theory
of modification and species-forming from all taint of La-
marckism; an attempt which resulted in his
Wejsmann's apparently successful overthrowal of the com-
monly accepted theory of the inheritance of
acquired characters, a theory or assumption which is a
fundamental and indispensable part of the general Lamarck-
ian theory. (Lamarckism and the inheritance of acquired
characters are explained and briefly discussed in chapter x of
this book.) On the strength of this success Weismann pro-
posed the doctrine of the Allmacht of natural selection ; that



I3 2 DARWINISM TO-DAY.

is, that natural selection alone is capable of explaining all the
phenomena and facts of species-forming and descent. At
the same time he developed and announced the theory of the
continuity of the germ-plasm, 2 which, in a word, is the
theory of an absolute separation of the germ-plasm from
the soma-plasm and consequently the thorough independ-
ence of this germ-plasm from all influence and control of
the soma-plasm, *'. e., all that part of the body other than
the germ cells. This carried with it the assumption that
all the phenomena of heredity and variation depended solely
on the germ-plasm and that the germ-plasm of any individual
is derived, unmodified by any somatic influences, directly
from the germ-plasm of its ancestors. This assumption in
turn led to the logical but startling conclusion that all the
capacity or possibility of variation for all time was present
in that primitive ancestral germ-plasm from which the germ-
plasm of all many-celled animals has been derived. But such
a nearly infinite capacity for furnishing variations demanded
the postulation of an equally nearly infinite capacity for ac-
tual physical or structural complexity on the part of the germ-
plasm itself, for biologists insist on a physical mechanism for
all the physiological phenomena they find in life. So Weis-
mann assumed an interesting but invisible and apparently
non-testable composition of germ-plasm out of life-units,
called-biophors, grouped into particles of a second order called
determinants. The biophors are taken to be much larger
and more complex units than chemical atoms, or even than
molecules. They are groups of several to many molecules,
each biophor, however, still ultra-microscopic, and represent-
ing a single characteristic of cell-life. Each biophor is as-
sumed to possess the essential attributes of living substance,
viz., the capacity to assimilate food, to grow, and to repro-
duce itself. The groups of biophors called determinants
are larger, of course, but yet invisible to our best micro-
scopes, and each represents all the characteristics which a



DARWINISM DEFENDED. 133

cell of any particular single, kind has. Thus one kind of
determinant represents all the attributes of the red blood
corpuscles, another of the nerve-ganglion cells, another of a
certain type of epithelial cells, and so on. Each determinant
has also the power of assimilating food, growing and re-
producing itself by division. Now the possibility of repre-
senting in the germ-plasm the nearly infinite capacity to
vary characteristic of this plasm has for its physical or
mechanical basis the minute size of the biophors and deter-
minants coupled with the inconceivably many combinations
of different kinds of biophors possible in the make-up of the
determinants which are, as already said, the actual structural
representatives of, or better, controllers or producers of,
the various kinds of body tissue and organs.

These three general assumptions of Weismann,* namely,
( i ) the composition of germ-plasm out of ultimate life-units
called biophors (grouped into determinants) which deter-
mine all the physical characteristics of the individuals into
which the germ-plasm develops; (2) the isolation (from the
soma) and the continuity (from generation to generation,
from beginning to end) of the germ-plasm; and (3) the
Allmacht of natural selection, which involves the discarding
of all other factors of modification and species-forming than
the natural selection of the slight fluctuating congenital
variations produced (in an unknown manner) by infinitesi-
mal changes in the determinants of the germ-plasm these
three fundamental and important Weismannian assumptions,
accepted more or less nearly completely by Wallace and a
number of other English biologists, and by a
ismandNeo- few naturalists of Europe and America, con-
Lamaickism. st i tute the essential position of what is called
neo-Darwinism. This neo-Darwinism immediately found
many capable antagonists, and as most of the antago-
nists were believers in some parts of the general theory
of adaptation and species-forming first proposed by



I34 DARWINISM TO-DAY.

Lamarck, their position came to be known as neo-
Lamarckism. Herbert Spencer in England, Packard,
Osborn, and others in America, and Eimer in Ger-
many were prominent exponents of the anti-Weisman-
nian views. The debate was spirited, and engaged many
biological writers, and interested the general reading
public in the larger problems of biology more than it
has been interested at any other time since the great struggle
immediately following the publication of Darwin's "Origin
of Species." The best known part of the general debate
was that carried on directly by Weismann and Spencer in
the Contemporary Review (1893 and 1894).

The general result of the struggle between neo;Darwin-
ism and neo-Lamarckism can be fairly stated to be, that
Weismann's assault on the theory of the in-
Conoessiottiuif heritance of acquired characters was in general
successful ; while, on the other hand, the assault
of the anti-Weismannians on the assumptions of the isola-
tion and continuity of the germ-plasm and of the Allmacht
of natural selection forced from Weismann and his follow-
ers, one by one and slowly, such radical concessions as to
make the latter doctrine utterly untenable, and to rob the
other of most of its significance in the consideration of modi-
fication and species-forming. The assumption of the com-
position of germ-plasm out of biophors and determinants
is of course merely an interesting speculation, or tentative
hypothesis, which, because it is untestable by scientific ob-
servation or experiment, cannot be debated to any particular
advantage. Weismann himself, in 1895, definitely conced-
ing that natural selection is radically weak at its base, being
incapable of explaining the beginnings of useful variations
and the development (which actually occurs) of indifferent
ones, proposed a new and radically un-Darwinian theory
under the name of Germinal Selection. This theory (ex-
plained in chapter viii of this book) although including the



DARWINISM DEFENDED. 135

word selection in its name is fundamentally different from
natural selection in the Darwinian sense, and is indeed
an admission of the existence of variations maintained (not
by means of natural selection) along definite lines, result-
ing in a real orthogenesis. It attempts to offer a causo-
mechanical explanation of such un-Darwinian development.
' By the theory of germinal selection, which is based abso-
lutely on the assumption that the plasm is composed of
biophors and determinants or at least of physical life units
of similar type and function, Weismann hopes to strengthen
four weak places in the general position of neo-Darwinism.
The theory explains (i) how in Panmixia (another Weis-
mannian contribution to neo-Darwinism, for account of
which see chapter viii) the degeneration of useless organs
is brought about, (2) how it is that for the continued
development of any certain complex adaptation exactly the
right variations shall appear at the needed time, (3) how co-
adaptation comes to exist, and finally (4) how variations
may come to be developed along fixed lines or in definite
directions without the aid of personal selection. Whether
the theory of germinal selection explains these four things
or not, what is to us for the moment the chief interest of the
theory is that it is put forward by Weismann, who is dis-
tinctly the foremost neo-Darwinian, to explain just these
things. For that makes of these things concessions that the
neo-Darwinians, the ultra-selectionists, feel forced to offer.
It should be noted, however, that perhaps Weismann does
not speak for all ultra-selectionists, for example, Lloyd
Morgan, Ray Lankester, and other English * Darwinians.
Certainly his theory of germinal selection is accepted by
few of them.

On the whole, however, I think I speak perfectly fairly
in saying that the believers and defenders of the natural
selection theory to-day admit in large measure the valid-
ity of those criticisms which are directed at the inca-



136 DARWINISM TO-DAY.

parity of Darwinism, in its long familiar form, to account
for the development of variations and modifications up
to the advantageous or disadvantageous stage. They admit
also the actual existence, and in abundant measure, of
species differences which are of indifferent character, that is,
of no especial utility, and make the consequent admission
that such species differences cannot for the most part be
explained by natural selection. And they also concede, or
at least most of them, including Weismann, do. -the force
of the criticism that the assumption of the occurrence of the
right variations at the right time is a necessity for the
development by selection of many if not most specialisations
of qualitative and of coadaptive character, which assump-
tion in turn demands an explanation of causes anterior to
selection.

And finally most selectionists concede that selection can-
not make new species by relying on the extremes of series
of fluctuating or Darwinian variations because of the
inevitable extinguishing or swamping of these extreme
variations by inter-breeding with the far more abundant
average or modal individuals of the species. Hence all
those objections recorded in the chapters on "Darwin-
ism Attacked" which have to do solely with this inca-
pacity of natural selection to make use of variations too
small or too few or purely fortuitous, or with the incapacity
of selection to explain hosts of indifferent, non-adaptive
species differences which actually exist, and hence with the
certainty of its not being the only factor, if indeed a prin-
cipal factor, in the formation of species, need not be re-
discussed, at least to any length, in this chapter. We may
also largely neglect those objections which are directed
against the purely hypothetical assumptions and the extreme
positions of the neo-Darwinians. Many of these assump-
tions, such as that of the absolute isolation and independence
from the soma of the germ-plasm, are not a part of Dar-



DARWINISM DEFENDED. 137

winism proper, and the extreme position of the believers in.
the Allmacht of selection was certainly never taken by Dar-
win himself. In fact, most of nee-Darwinism has been
deserted by its one-time followers, and most conspicuously
and perhaps most radically by Weismann himself.

Thus, with these two categories of objections listed in
the/ "Darwinism Attacked" chapter put to one side, for the
moment at least, by admitting the validity of one category
and showing the inapplicability of the other as regards its
relation to true Darwinism, we have left to us
to consider those remaining objections which
are made (i) against the capability of selec-
tion's making any use at all of the familiar and always
occurring fluctuating variations called Darwinian, (2)
against its capacity to explain coadaptive and highly com-
plex adaptations, especially those which seem as if they
could be of advantage to the organism only in fully
developed or specialised state, (3) against its inability to
account for overdeveloped specialisations, (4) against the
possibility of selection's explaining qualitative differences in
species, and many-branched descent (quantitative differ-
ences and linear descent seeming to be the only kinds pos-
sible to it), (5) against its capacity to explain complete
or extreme structural degeneration of useless organs and
parts, (6) against the reality and extreme rigour of the
struggle for existence and personal selection (an essential
foundation of the selection theory), (7) against the sexual
selection theory, particularly in its capacity as a supporting
prop of the natural selection theory, (8) against the reliance
by the selectionists on the homology or analogy which they
hold to exist between natural selection and artificial selec-
tion, and finally to consider those curiously positive and
definite declarations of such radical anti-Darwinians as
Wolff. Korschinsky. and others that natural selection is a
vagary, having no claims to existence either on a basis of



138 DARWINISM TO-DAY.

observation or logical reasoning, or that if it exists its whole
influence is directly inimical to changes and evolution rather
than of a nature to produce and foster them. The most
comprehensive, fairest, and most effective recent attempt
to gather together and meet seriatim the objections and
criticisms of Darwinism is (as already stated in the chapter
on "Darwinism Attacked") that of Ludwig Plate, 5 and I
have therefore given considerable space in this chapter to
direct quotations from the answers and discussions of this
modern Darwinian champion.

The objection made that natural selection can make no use

at all of the small fluctuating Darwinian variations is really

a wider application of the really valid objection

Answer to the * J

objection that that such variations cannot, or can only rarely,
1 " offer material for the production by selection of



slight to be of new organs and that for many adaptations
they are too slight to be of use and hence
cannot serve as handles for selection. As a matter of
fact, however, many adaptive modifications are purely quan-
titative, not necessarily involving any qualitative change
at all. Increase in general size, or in any one dimension
of an organ or part, meaning often an increase of strength
on the part of the animal, in the capacity for aggres-
sion or defence, in swiftness, in flight, running or swim-
ming, in reaching or digging or climbing or leaping
such an adaptive modification might well be brought about
by selection of even very inconsiderable enlargements or
strengthenings of one or more organs or parts. Wherever
the modification is in a directly linear path, and an advantage
is possible through even slight advances or regressions along
this line, natural selection will find in the Darwinian varia-
tions a means of fostering and perfecting this modification.
There are just two requirements necessary for the Darwin-
ian variations to meet in order to serve as handles for
natural selection: they must be variations actually suffi-



DARWINISM DEFENDED. 139

ciently useful and advantageous to turn the scale in the intra-
or inter-specific struggle for existence in favour of the
individuals possessing them, and they must occur in suffi-
ciently many individuals to avoid being swamped or
extinguished by cross-breeding : that is, they must be useful
enough to be selected and numerous enough to perpetuate
themselves. Do Darwinian variations ever meet these re-
quirements? Unfortunately our proof is rather indirect:
observation reveals their abundance, but does not actually
show their utility. 9 To answer the question our judgment
and reason, based on our knowledge and experience of the
existing conditions of animal and plant life, will have to
be trusted for answer. How real is the rigour; how keen
the struggle ; how crowded the square yard or square mile ;
how great or how little must be the differences in a part to
give a life-or-death decision in the competition? Each
naturalist must answer this for himself, and the layman
must take the general consensus of opinion of the natural-
ists, if there is one, for his answer.

The objection to the linear and quantitative character of

the Darwinian variations has been recently especially urged

by de Vries in connection with his exposition

oiijectionoon- * ^ tneorv * species-forming by mutations.

cerningthe The selection theory reckons with linear hence

linear and quan- . . . .

titative charac- strictly quantitative variations, says he, and yet
ter of fluctuating j s presumed to create new forms for which in

variation. ... . .

reality qualitative variations are necessary as
a basis, so that in fact selection can only increase or
diminish, add to or subtract from characters already in
existence and cannot create anything new, this appear-
ance of new characteristics being, however, precisely the
principal peculiarity of new species, taken by and large. This
position of de Vries has been discussed by Plate T as follows :
"I call attention in advance to the fact that de Vries
understands by 'linear variations' what are more usually



I 4 o DARWINISM TO-DAY.

known as individual, fluctuating or continuous variations.
He has chosen this name because the single characteristic
can change toward but two directions; that is, toward the
plus, or toward the minus direction. In contrast to this
kind of variation stand the sudden and discontinuous leap-
like changes or mutations which have been for the first
time carefully investigated by the praiseworthy labour of
de Vries, hitherto having been familiar indeed under the
names 'single variations' or 'sports,' but little studied. Con-
cerning these linear variations de Vries writes : 'The statis-
tical method of the study of variation has now been so
generally followed as to make its principles familiar without
further discussion, and they may be considered as accepted.
The chief principle indicated by the use of the frequency
curves is that the characteristics vary in but two directions,
that is toward plus or toward minus. The old vague con-
ception of an all-sided variation of the single characters
has disappeared of its own self.'

"As highly as I appreciate the great service of de Vries
in relation to our knowledge of the suddenly appearing
changes, heritable in high degree, I must nevertheless op-
pose him in his conclusions touching the selection theory.
In the first place this theory does not reckon alone with
linear variations, but also with mutations, if they appear,
for it takes the changes as given material without troubling
itself about differences in their mode of origin. In the
second place it is not correct that a character cannot so
change itself through simple addition or reduction that it
may not be, in the customary classificatory limits, looked on
as a new character. A smooth leaf, a leaf with few small
hairs, and one with a thick wool show only linear variations,
but in spite of that they may very well serve as character-
istic of different species. Nearly related butterflies recall
the Vanessas and Lycaenas often show the same funda-
mental characters of pattern and form, so that they are dis-



DARWINISM DEFENDED. 141

tinguished only by plus or minus variations. Indeed one
may consider the whole endless manifoldness of organic
combinations as only representing greater or lesser num-
bers pf atoms of the same few elements which are bound to-
gether in one molecule. In the third place the statistical
studies of variation have not shattered in any respect the
Conception of an all-sided variation of the single characters,
but indeed on the contrary have rather shown that all the
parts and attributes of organisms that are accessible to
observation appear to us more or less different in different
individuals. This all-sided variability has nothing to do
with the statement that each single variable element can
vary always only toward plus or toward minus. Blue
flower petals can appear more or less blue and at the same
time reveal their indeterminate, fortuitous, or all-sided
variability in differences of form, hairiness, thickness,
structure, etc. The same indeterminateness which de Vries
claims for his mutations is characteristic also of linear



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 13 of 38)