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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 21 of 38)
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been able to drop this weakest part of the Darwinian conception.
So that in the theory of the later biologist, the circulation of gem-
mules does not extend from one cell to another throughout the
body of the organism, but limits itself to that particular cell in
which it is created and circulates only between the nucleus and
cytoplasm, from which comes the name, "intra-cellular pangenesis,"
as distinguished from Darwinian pangenesis. De Vries' theory may
be abstracted as follows (following Delage) :

The form and properties of cells result from their protoplasmic
composition just as the properties of the inorganic bodies result

De Vries's from their chemical composition. Is it necessary, then,
theory. to admit that there are as many kinds of protoplasm as

there are different sorts of cells in the organised beings? When one
recalls how many different cells there are in a single organism, and
that the homologous cells are not identical in different species, one



OTHER THEORIES OF SPECIES-FORMING. 221

realises the incalculable number of these cells and despite the rich-
ness in variety of proteid substances, it will be impossible to con-
ceive that each kind of cell should have its own kind of proto-
plasm. There is here, apparently, an insurmountable difficulty, but
one which it is easy to do away with by a very simple concep-
tion. This conception consists in distributing the complex charac-
ters and properties, innumerable in living beings, into elementary
characters and properties much less numerous, which, by varying
combinations, produce the almost infinite variety that we observe
in the inorganic world. Just as with a score and a half of letters
one may form all of the words of the human language, so with the
elementary properties of which the actual number is still very con-
siderable, one may reproduce all the characters of living beings in
all their variety and complexity. It suffices, then, to admit that
these elementary characters and properties are represented by as
many material particles, and the problem is solved. These particles
are the pangenes.

The pangenes, then, are small, organic particles, invisible to
the microscope, formed of an enormous number of chemical mole-
cules and differing from the most complex chemical substances
by three properties which are common to all of them and which
are characteristic of living matter; they nourish themselves, in-
crease in size, and multiply themselves by division. Beside these
three general properties which make living molecules of them,
the pangenes possess particular properties depending upon their
chemical constitution, differing for each of them, and which are
bound to them indissolubly in such a manner that, wherever a
pangene finds itself, the elementary property or character special to
it will show itself if internal and external conditions permit of this
manifestation. Latent or patent, potentially or evidently, the char-
acter is always there where is the corresponding pangene. Each
cell contains a great number of pangenes in activity, and its charac-
ters and properties in sum are the resultant of the elementary
characters and properties of the pangenes composing it: just as the
anatomical and physiological characters and properties of the living
Individual are resultant of the anatomical and physiological charac-
ters of the cells composing it.

It is necessary to conceive of the cellular protoplasm as formed
of innumerable pangenes bathed in a liquid in which are dissolved
substances purely chemical : albumen, glucose, salts, etc. Perhaps
similar substances penetrate the pangenes themselves, but we do
not know this.

The nucleus contains in general all the kinds of pangenes that
compose the individual. But these pangenes are there in a sort



222 DARWINISM TO-DAY.

of inactivity, in reserve, in order to be transmitted to the daughter
nucleus when the cell divides. They can divide themselves, and it
is indeed necessary that this be so in order that the two daughter
nuclei can each receive a complete lot of the representative pan-
genes; but they do not manifest in the nucleus their special proper-
ties, which remain in a latent state. There is no exception to this
except in the case of those certain pangenes which control the
division of the nucleus. These enter into activity at the necessary
moment in order to determine the characters of the division and
in particular the position of the plane of segmentation.

The cytoplasm is also composed of pangenes; but these pangenes,
with the exception of those which come from the cytoplasm of the
egg, come from the nucleus. From the nucleus there come, in fact,
pangenes which distribute themselves in the cytoplasm and multiply
there abundantly. These pangenes are exclusively those of which
the cytoplasm has need in order to manifest characters and proper-
ties which belong to the cell, and it is by delivering to it such and
such pangenes and no others that the nucleus rules the cytoplasm,
which would remain inert were it not for this infusion of living
and active particles.

There is, then, a great difference between the nucleus and the
cytoplasm from the point of view of the pangenetic constitution.
Each nucleus contains in general all the pangenes of the individual
united undoubtedly into groups more or less considerable, which lie
in the chromatic filaments, and these groups, analogous to the
gemmules of Darwin's theory, probably form those little grains
arranged in rows, which are revealed under a great microscopic
magnification of the chromatic threads. But there are one, two, or,
at most, a small number of pangenes of each kind ; all are inactive
save at the moment of division, those which rule this phenomenon ;
they can multiply themselves but slightly, and in general they do
not divide except to replace those which emigrate into the cyto-
plasm and to furnish at the moment of division to each daughter
nucleus the complete lot which it ought to receive. In the cyto-
plasm, on the contrary, there is but a small number of kinds of
pangenes immigrated from the nucleus in the quantity exactly
necessary, but there these pangenes are enormously multiplying, so
that there is a very great number of each kind, and they are almost
always in a state of activity.

B. Hatschek has recently proposed ("Hypothese der Organischen
Vererbung," 1905) a new micromeric theory which postulates that

Hatsohek's the protoplasm is composed of two different kinds cf
theory. biomolecules ; one called ergatules, which function as-

similatively, that is, take up food-stuff and excrete waste, but do not



OTHER THEORIES OF SPECIES-FORMING. 225

possess a capacity for growth or self-reproduction; second, the gen-
eratules, which have no particular functional work to perform but can
grow and reproduce themselves and can carry over this capacity of
reproduction to the ergatules, because they can fuse with them or
attach themselves to them and thus carry over to them their char-
acteristic peculiarities. These generatules are looked on as the
chemical radical of the ergatules, and become therefore the directly
determining agents for all peculiarities of the body. The ergatules
sit chiefly in the cytoplasm of the cell, while the generatules lie in the
cell nucleus, especially in the chromosomes, and therefore render
these the bearers of hereditary characteristics.

Thus baldly and wholly incompletely stated these theories of
ultimate plasm structure which shall be of a sort to agree with all
the varied phenomena of life, and particularly those of heredity,
show, unfortunately, only their fantastic face. For as it is pre-
cisely in showing how the postulated structure and properties are
perfectly consonant with all the known phenomena of life that
these theories have their actual interest and strength, a fantastic
and improbable face shown as to this robs them of all interest. But,
perhaps, it is well that the fantastic aspect of them should be first
recognised. For it is only fair to say that the ingenuity and plausi-
bility, the precise and exhaustive development of detail, of some of
these theories, are really dangerous to the layman who first happens
to read a full and well-stated account of one of them by an enthu-
siastic upholder. One's eyes become closed to the fact that all the
structure and performance that seem so natural, and fit in so
exactly with all that we actually know of the phenomena of life,
have not been seen, only imagined. One needs an introduction to
these theories which insists above all on their wholly hypothetical
character. Otherwise one is surprisingly readily hypnotised into
accepting one or the other of them as a statement of fact. These
general theories are the atomic theories of biology without one-
tenth the probability of truth or one-tenth the actual acceptance
in science that the atomic theory of the chemists has. And even
that is beginning to be discarded in modern chemistry. These
theories are, as Weismann has said, the outcome of the fact that
"the deeper one studies into the phenomena of heredity, the more
one is convinced that something of this kind of a condition [of a
composition of the fundamental life substance out of ultra-micro-
scopic units bearing a certain spatial relation, and one of attractions
and repulsions to each other] must really exist: for it is impossible
to explain the observed phenomena in any other way, that is. by
any much simpler assumption." But on the other hand a sufficient
reason against accepting any one of these highly developed theories



224 DARWINISM TO-DAY.

of the structure and functional capacity of invisible life-units, is
the sagacious one of Delage when he says that simply by the law

Delage's of probabilities it will be impossible by pure imagining

criticisms. to explain correctly in detail the ultimate structure

of protoplasm. Has any one, asks Delage, guessed in advance, with
the least truth, structures which the microscope has later been able
to reveal to us? Has any one guessed the cross-striation of muscles,
the cilia of vibratile epithelium, the prolongations of the nerve-
cells, the make-up of the retina, or the organ of Corti, the chromo-
somes, the centrosome? Distinctly not. Delage points out that
the chemists had a much better chance to hit the truth in supposing
atomic structure, for they had a much less complex condition to
perceive, and they had approached in their positive knowledge very
much nearer the hypothetical element which they adopted.

Le Dantec criticises the micromeric theories of protoplasmic
structure by saying that all these theories seek to make mysteries

Le Danteo's clearer, complex things simpler, by reducing large
criticisms. things to small ones. A man, for example (he says)

is composed of 60 trillions of cells and is nevertheless produced by
sexual elements of very small size; here is a phenomenon to ex-
plain. The micromerist says that the difficulty of this explanation
would be less (or at least not so sharply defined!) if one divided
the problem into 60 trillions of parts ; that is, if one replaced the
reproduction of man by 60 trillions of partial reproduction. One
has therefore imagined particles infinitely small which are to the
cells what the sexual cells are to the man. And this comparison has
been, consciously or not, claims Le Dantec, the point of departure
of all the systems of particulate representation in the germ-
plasm.

We have simply substituted for a single heredity, continues the
critic, 60 trillions of partial heredities, each exactly as mysterious
as the first. Thus these 60 trillions of gemmules gathered in the
egg and distributed in a precise manner are in reality only a dis-
guising of the homunculus of the ovalists. Perhaps we have no
reason to suppose that these gemmules design by their agglomeration
this invisible homunculus, but at least it is certain that they
are disposed in a manner which is in relation to the form of the
man to be determined, since in fact each of them represents not
alone a cell of the man. but a cell with the place it is to occupy.

One sees thus how complex is this system which has for its aim
the simplifying of the question of heredity: it is more logical to
consider simply the egg as having the power to produce a man than
to attribute a power as mysterious to 60 trillions of gemmules to
which it is necessary to accord, in addition, a determinative capacity



OTHER THEORIES OF SPECIES-FORMING. 225

which results in conducting each cell to exactly that place which
it ought to occupy.

In addition to the theories of an ultimate micromeric structure
of protoplasm, certain other recent hypothetical explanations of

Verworn's bio- the special properties of protoplasm should be noted.
gen hypothesis. One is the biogen hypothesis of Verworn, the physiol-
ogist of Gottingen, one the chemism theory of Le Dantec, one
the physical machine theory of Delage, and another is the general
vital' principle hypothesis of the neo-Vitalists. Verworn's hypoth-
esis to account for the physiological activities of protoplasm, i. e.,
the special life attributes, as assimilation, disassimilation, growth,
irritability, etc., consists in the postulation of a complex chemical
compound of unknown structure called biogen, but with the speciaj
capacities of an enzyme. This biogen is assumed to be constantly
labile, i. e., breaking down and rebuilding itself and by this per-
formance acting as a go-between (enzyme or perhaps katalysator)
between the atmospheric oxygen brought to the cell by the blood
and the oxidisable (food) products (also brought by the blood).
Not only can the biogen rebuild itself, but by polymerisation it can
grow, that is, increase the size of its molecules by adding side-
chains of atoms. This, according to Verworn, constitutes cell
growth. This growth is not indefinite, as the atoms tend to break
away again and thus there is a limit to the size of the biogen mole-
cules. The author only presents his conception of biogen as a good
working hypothesis.

Delage has also offered a tentative physico-chemical explanation
of certain of the properties of protoplasm, as its movements, its

Delage's ma- nutrition, and even its reducing division, on the basis
chine theory. o f osmotic effects due to the constant interchange of
substance from the outer layers of the cell protoplasm to the inner
through fine membranes or special protoplasmic layers which he
assumes to enclose each cell part, i. e., nucleus, chromosomes, etc.
Nutrition, for example, is effected according to Delage, by constant
selective osmotic exchanges between the liquid and semi-liquid
parts of the cell, the blood-plasm of course constantly bringing
food and carrying off excreta to and from the periphery of each
cell. Cell division is the result of mutual pulls and pushes, its
essential feature always being the actual sundering of parts; but
how this mechanical process is guided or controlled as it is, or even
initiated, is left unexplained.

Le Dantec holds that life is a chemical phenomenon. "La vie est

Le Dantec's the- un phenomene chimique, c'est-a-dire que les seuls
ory of chemism. caracteres essentiels par lesquels une action vitale
differe d'une manifestation de 1'activite de la matiere brute sont rela-



226 DARWINISM TO-DAY.

tifs a des destructions et des constructions d'edifices moleculaires.
Cette verite, toute la biologic nous la prouvera de mille manieres ; il
vaut done mieux 1'enoncer en commengant, de maniere a ce qu'elle
prenne la premiere place dans 1'esprit de ceux qui se livreront a
1'etude des etres vivants.

"Mais une reaction chimique n'est pas quelque chose d'isole et
ne se produit que dans certaines conditions dont la realisation peut
etre liee a des particularites d'ordre physique (chaleur, electricite,
lumiere, etc.) ; de plus, elle s'accompagne toujours de phenomenes
accessoires qui sortent egalement du domaine de la chimie (chaleur,
mouvement, etc.). Ceci est vrai surtout pour les reactions des
matieres vivantes, a cause de 1'etat tres special de ce qui represente
la solution de ces matieres dans 1'eau. La vie est aquatique, mais
les matieres vivantes ne se dissolvent pas comme du sel marin"
("Traite de Biologic," pp. 43-44, 1903)-

He goes on to discuss, with keen analysis and ingenious but uncon-
vincing synthesis, the various primary conditions and activities of
life, explaining each vital phenomenon separately on a basis of
chemism. He even proposes a chemical notion of species. Such
a chemical species can of course take no primary account of form,
but as conditions of chemical identity will usually involve identity
of form, the various individuals composing a chemical species will
possess a similar or identical form. An author, undertaking what
Le Dantec undertakes, must necessarily be a bold thinker and a
bold writer. The present author is both. And he is nowhere unin-
teresting or unsuggestive, but also is he nowhere wholly con-
vincing.

The position of the neo-Vitalists is perhaps best to be taken
from that of Driesch, an extremely able present-day biologist, whose
Neo- Vital! ^ rst ^ e ^ e ^ was m a radical mechanical explanation of
all life phenomena, and whose brilliant experimental
work has furnished many of the examples referred to in all text-books
of the modern study of the mechanics of development. But Driesch's
present position is an uncompromising belief in the impossibility
of explaining life-forms and life-functions on the basis of ever so
complex a combination of purely physico-chemical and mechanical
conditions and factors. Put positively, neo-Vitalism demands the
assumption of an extra-physico-chemical factor (called "psychoid,"
according to Driesch's nomenclature), which is an attribute
of, or essential kind of potentiality pertaining to, organised
living substance, and not found in nor influencing inorganic
bodies.

Biitschli has well pointed out that neo-Vitalism is really only
a return to the old "vital principle" belief, and that we are now,



OTHER THEORIES OF SPECIES-FORMING. 227

and have been ever since our practical giving up of the vital prin-
ciple notion, making steady progress in the explanation of life-
forms and life-functions on strictly mechanical and physico-chemical
grounds. While we have by no means explained all life attributes
in this way, Biitschli holds that our progress has been such as to
make no demand for the introduction as yet of a new vital principle
under a pseudo-scientific guise.

Other neo-Vitalists. of whom G. Wolff is a type, lay chief stress
on the inexplicableness of the Zweckmassigkeit in organisms by
any of the known biological facts and factors, and see in the deter-
mination or very existence of this Zweckmassigkeit the chief revela-
tion of a vital factor, wholly distinct from anything found in the
inorganic world. Wolff's argument is clever and suggestive, and
brings home to one strongly the indissoluble relationship between
living matter and its adaptivity. In its fundamental character life
is adaptivity : the indispensable relation between living matter and
the rest of nature is the pliability, the adaptiveness of the living
matter. "Die sweckmdssige Anpassung ist das, was den Organis-
mus zum Organismus macht, was sich uns als das eigentlichste
Wesen des Lebcndigen darstellt. Wir konnen uns keinen Organis-
mus denken ohne dieses Charakteristikum. . . . Und wir erkennen
dass jede Erklarung, welche das Leben voraussetzt, jede postvi-
tale Erklarung der organischen Zweckmassigkeit, in jedem
Falle voraussetzt was sie erklaren will ; wir erkennen dass die
Erklarung der Zweckmassigkeit mit der Erklarung des Lebens
zusammenf alien muss."

But perhaps there is a difference between the plastic response of
protoplasm to the varying conditions of oxygen, food, temperature,
etc., about it, so that within certain limits of external versatility it
still lives, and that extraordinary specialisation of fitness which we
see exhibited by a parasitic Sacculina with relation to its crab
host. And believers in natural selection hold that it is exactly one
of the chief glories of selection that it does explain this highly
specialised fitness. More than that, closer examination of the
phenomena of organic Nature reveals many examples of an unfit-
ness, which certainly ought not to exist if there is a special vital
principle responsible for fitness throughout the organic kingdom.
There is a moth common with us here in California, by name
Phryganidia californica, whose larvae live on the leaves of the oak-
trees. Two generations appear each year. The eggs for the first
brood of caterpillars are laid in spring by the moths on the leaves
of the live-oaks and also of the white-oaks. The larvae soon hatch,
feed through the summer on the leaves, and in September pupate,
the moths appearing in October. These moths now proceed to lay



228 DARWINISM TO-DAY.

the eggs for the second generation, which eggs are also deposited
on the leaves of both live- and white-oaks. But while the live-oak
is an evergreen tree, the white-oak is deciduous, and sheds its
leaves soon after these October eggs are laid on them, which means
that one-half of this second generation is doomed to die of starva-
tion immediately after hatching. This is repeated regularly each
year, and is certainly a distinctly unfit habit in this moth's life
economy. Plate refers to a similar instance of Unzweckmassigkeit
as follows: "As I once was landing on Santa Maria Island in the
Gulf of Aranco, the whole shore swarmed with thousands of giant
cuttlefishes (Ommatastrephes gigas) which partly lay dead on the
beach and partly were swimming around in the shallow water.
These latter instead of trying to get back into deeper water, con-
stantly swam towards the land until a breaker threw them up high
and dry. Reflexes and instincts often make mistakes, that is, they
result in actions which result in actual harm, and nothing is more
mistaken than the declaration that an organism reacts under normal
circumstances always in a way to serve the preservation of its life.
That organisms under new circumstances or in abnormal condi-
tion very often react unfitly, requires no elaboration ; every light-
house against which thousands of birds and insects are killed, the
toxicological phenomena, the incomplete regeneration, every club-
foot, and every Wasserkopf prove this. The countless harmful re-
actions and incompletenesses in structure make it impossible to
speak, in the vitalistic sense, of an inherent Zweckmassigkeit of
organisms, of a tendency always to change in the direction of use-
fulness. An organism is exactly as definitely ruled by chemico-
physical laws as every dead body. Let an organism happen in any
set of conditions : it has no longer the choice among a useful, a
harmful, or an indifferent reaction, but the causal chain determines
for a definite direction and this is, as a thousandfold observations
show, not a life-preserving one, in other words is not zweckmassig.
If now in spite of this organisms have become, in the course of
earth-history, even more complex and more capable and have
acquired the most wonderful adaptation, there must obtain some
regulatory principle in Nature, which we, with Darwin, recognise
as actually existing in the struggle for existence and the con-
sequent selection of fit variations. If organisms actually had the
capacity to direct their vital activities always toward the side of
utility, then the workings of the natural forces would be over-
come and Mysticism again be introduced in natural philosophy.
Both actual observation and the theoretical basis of natural science
give no basis for any hypothesis of the existence in organisms of
an immanent capacity for adaptive reactions."



OTHER THEORIES OF SPECIES-FORMING. 229

5 Weismann, A., "On Germinal Selection as a Source of Definite
Variation," trans. McCormack, p. 3, 1896.

9 1 quote from Morgan, "Evolution and Adaptation," pp. 165-166,
1903, the following special protest against the means of escape from
Morgan's criti- a tight place which Weismann has taken advantage of
cismofWeis- in his dilemma: "Thus Weismann has piled up one
mann's method hypothesis on another as though he could save the
of argument. integrity of the theory of natural selection by adding
new speculative matter to it. The most unfortunate feature is that
the new speculation is skilfully removed from the field of verifica-
tion, and invisible germs whose sole functions are those which
Weismann's imagination bestows on them, are brought forward



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 21 of 38)