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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 20 of 38)
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ing each other and distinguishing each other from the
original seven cm. individuals, mixed mating will inevitably
soon swamp the original congenital increase of one cm. in
muscle thickness.

In connection with the explanation of this theory it will
certainly occur to some of my readers, as it has to me, to ask
Danger of ^ ^ * s not a dangerous proposal to give to
assuming too ontogenetic adaptations a greater worth in
See ofonto-" deciding the fate of individuals during the
genetic selection, struggle for existence than the congenital varia-
tions. Is this not proposing to take away from the fluctuat-
ing, individiual, so-called Darwinian variations practically
all worth and capacity except as they are of immediate use
to the just-born individuals, i. e., before the ontogenetic
adaptations have been able to develop ? Indeed, why is it not
a perfectly legitimate and a serious criticism of congenital
fluctuating variations that they must be overshadowed, hid-
den, and overwhelmed by the quick and large ontogenetic
or individual modification of which practically all organisms
are capable? Why will not those individuals born with the



212 DARWINISM TO-DAY.

better and larger capacity to adapt themselves during their
ontogeny to their needs win in the struggle for existence
rather than those born with predetermined slightly larger
leg, slightly stronger muscle, etc.? What is needed is
capacity to develop by use and functional stimulus a much
stronger muscle, a much swifter flight than the average.
Those individuals that are capable of such considerable and
really worth while ontogenetic adaptation will win in the
struggle for existence ; and while they may not hand down
by inheritance their actually acquired characters, will they
not hand down their inherited congenital capacity for con-
siderable and effective ontogenetic adaptation ?



APPENDIX.

1 For a fairly complete bibliography, with abstracts, of all the
important discussions of species-forming theories published since
1895, see L'Annee Biologique (ed. Y. Delage). For bibliography
and abstracts, also see Zoologischer Jahresbericht, issued annually
by the Naples Zoological Station. See also discussions and notes
in various biological journals, as Biologisches C entralblatt , Natural
Science (now discontinued), Nature, Science, American Naturalist,
etc.

2 For a careful account and discussion of Weismann's work and
theories as far as developed up to 1893, see Romanes, "An Exami-

ListofWeis- nation of Weismannism," 1893. Weismann's pres-
mann's evolution ent-day position and his arguments for the selection
papers. theories are set out in his "Vortrage iiber die De-

scendenztheorie," 2 vols., 1902. which we may look on as consti-
tuting a manual of neo-Darwinism, treating all the more familiar
bionomic phenomena and conditions as explained by selection.
The following is a chronological list of the more important of
Weismann's publications :

"liber die Berechtigung der Darwin'schen Theorie," 1868.

^'Uber den Einfluss der Isolirung auf die Artbildung," 1872.

"Studien zur Descendenztheofie : I, Uber den Saison-Dimorphis-
mus der Schmetterlinge," 1875.

"Uber die Dauer des Lebens," 1882.

"Uber die Vererbung," 1883.



OTHER THEORIES OF SPECIES-FORMING. 213

"Uber Leben und Tod," 1884.

"Die Continuitat des Keimplasmas als Grundlage einer Theorie
der Vererbung," 1885.

"Uber den Riickschritt in der Natur," 1886.

"Uber die Bedeutung der Sexuellen Fortpflanzung fiir die Selec-
tionstheorie," 1887.

"Uber die Zahl der Richtungskorper und fiber ihre Bedeutung
> fiir die Vererbung," 1887.

"Botanische Beweise fur eine Vererbung erworbener Eigenschaf-
ten," 1888.

"Uber die Hypothese einer Vererbung von Verletzungen," 1889.

"Bemerkungen zu einigen Tages Probleme," 1890.

"Gedanken fiber Musik bei Tieren und beim Menschen." 1890.

"Aufsatze fiber Vererbung und verwandte Biologic," 1892. (This
includes the eleven preceding papers now published in book-
form. These essays have also been translated into French,
by H. de Varigny, and published under the title: "Essais sur
1'Heredite et la Selection Naturelle," 1892; and also in Eng-
lish as "Essays upon Heredity and Kindred Biological Prob-
lems," trans, and ed. by Poulton, Shoneland, and Shipley, 2
vols., 1891 and 1893.

"Amphimixis oder die Vermischung der Individuen," 1891.

"Das Keimplasma; eine Theorie der Vererbung," 1892; Eng.
trans., by Parker and Ronnfeldt, as "The Germ-plasm; a
Theory of Heredity," 1893.

"Die Allmacht der Naturzuchtung, eine Enviderung an H. Spen-
cer," 1893 ; also in English as "The All-sufficiency of Natural
Selection," in the Contcmp. Review, Vol. LXIV, pp. 309-338,
596-610, 1893.

"The Effects of External Influences upon Development," Romanes
Lectures, 1894; also in German as "Aussere Einflfisse als
Entwicklungsreize," 1894.

"Neue Gedanken zur Vererbungsfrage," 1894.

"Uber Germinal-Selection," in Compt. Rendus, 3d Congress In-
ternat. Zool., 1896 ; also, in English, trans, and ed. by Mc-
Cormack, as "On Germinal Selection as a Source of Definite
Variation," 1896.

"Thatsachen u. Auslegungen in Bezug auf Regeneration," Anat.
Anzeig., Vol. XV, 1899.

"Vortrage fiber Descendenztheorie," 2 vols., 1902; also in Eng.,
trans, by J. A. Thomson as "Lectures on the Theory of
Descent." 2 vols., 1904.

3 For a detailed critical discussion of panmixia, see Wolff, "Der
gegenwiirtige Stand des Darwinismus," 1896.



2i 4 DARWINISM TO-DAY.

' Various theories of ultimate protoplasmic structure have been
proposed to explain what is not really known about this substance.
Theories of ul- These theories refer almost exclusively to the physi-
timate protoplas- cal, rather than the chemical, make-up of protoplasm,
mic structure. and for the most part have been proposed with
special attention to the germ-plasm, i. e., the protoplasm of the sperm-
and eg^cells. The spur to the formation of these theories is the
necessity that biologists have felt imposed on them from the be-
ginning of the study of heredity and development of offering some
rational explanation of those phenomena. That from a single germ-
cell formed by the fusion of a sperm-cell and an egg-cell from
different parents, a complete new organism composed of millions
of cells of manifold variety of specialisation and arrangement can
develop, is wonder enough; but that this new organism shall repeat
in all its parts with extraordinary fidelity the structure and physi-
cal idiosyncrasies of one, or show a combination of the character-
istics of both, of the individuals from which came the original
single sperm- and single egg-cell, adds wonder to wonder. What
physical or structural basis is there in the fertilised egg-cell that it
can represent in its tiny self the whole of a giant body, like that of
an elephant, whose every detail it can, by a process of development
under suitable extrinsic conditions of temperature, food-supply, etc.,
repeat in a new creature. The answers to this, all purely specula-
tive, or more fairly theoretical, because some of the answers at
least have been guarded in their forming by all the care which a
rigorous scientific attitude toward hypothesis demands, are many
and various, and date from the days of the Greek philosophers to
the present hour. It would take too much space and carry us too
far afield to attempt anything like an explanatory list of even all
of the better known of these general theories of the invisible ulti-
mate structure of the germ-plasm here, but by selecting seven or
eight types of the principal categories or kinds of these theories,
and briefly explaining them, we may have at least some conception
of the attitude that biologists take toward this great problem. The
reader who has a fancy for following this subject further is re-
ferred to the admirably full and lucid treatment of it in Delage's
great work, "L'Heredite" (ad ed., pp. 431-772, 1003).

Most of these theories include much more in them than a simple
speculation as to the ultimate structure of the life-substance; they
attempt to explain all the phenomena of life, motion, nutrition,
growth, reproduction, development, heredity, variation, etc., with
reference to some assumed ultimate make-up of the primitive life-
substance, and the relation of this structure to the known physico-
chemical forces and conditions of Nature. Most of the older



OTHER THEORIES OF SPECIES-FORMING. 215

theories assumed a peculiar vital force, which is not assumed in
the later ones, although exception must be made to this statement in
favour of the point of view held by the recent so-called neo-Vitalists,
those present-day workers who admit the hopelessness of trying to
reduce all vital phenomena to a physico-chemical basis.

An old type of theory of heredity and structure of the germ-
plasm, widely held in the seventeenth and eighteenth centuries, is

Encasement that of the "encasement of the germ" in one of the
theory. germ-cells, either the spermatozoid or the egg. The

essential part of this theory is that the new organism is assumed
actually to exist in miniature, with all its parts present, in one of the
germ-cells, and in this miniature body must exist, by repeated encase-
ment, all its future progeny. Whether the believer in this theory con-
sidered the tiny new creature, only needing to swell and grow to be
complete, to be encased in the sperm-cell or the egg-cell, ranked
him respectively with the spermatists or the ovalists. A vigorous
strife raged between these two factions among the upholders of
this simple and effective explanation of heredity which led to cer-
tain interesting compromises. A commonly held one was that the
sperm-cell furnished the spiritual element, the egg-cell the material
and mechanical elements of the new creature. Another, held by
Linnaeus, the great botanist and father of biological classification,
was that, in plants, the egg (ovule) furnished the internal and re-
productive organs, while the sperm-cell (pollen) furnished the exter-
nal and vegetative parts. De Candolle, another great botanist, held
just the reverse of this view. All these theories of an actual
encasement in the germ-cells of a whole or part of a new organism
were not mere guesses, but were based on what men thought they
saw through their microscopes. The long reign of these theories,
now shown to be utterly absurd, illustrates well the constant dan-
ger which attends our attempts in all biological study to interpret
what we see when working at the limits of visibility. With our
much-improved microscopes we laugh at the fantasies which the
microscopic vision of our eighteenth-century co-workers raised up.
Who may say that our own interpretations of plasm-structure may
not seem as absurd to the biologists of the next century?

By far the great majority of theories of ultimate protoplasmic
structure belong to what Delage calls the category of theories of
Micromeric micromerism. Which means simply that all these
theories. theories assume a composition of the plasm out of

minute ultra-microscopic units of structure, which are also units
of life, for all these units are presumed to be endowed with the
essential life-attributes. These units may be looked on, as they
were by Buffon, as universal, indestructible, hence immortal, parti-



2)6 DARWINISM TO-DAY.

cles, or, as they are in most of the micromeric theories, as living
particles which are destroyed with the death of the organism
which they compose. In this latter type of assumption the units
are, according to some theories, all of the same nature, all exer-
cising an equal influence in determining the character of a devel-
oping organism (Spencer, Haacke. His, Cope) ; or they are, as
assumed in other theories, of various character and charged with
various functions. This latter kind of unit is held by some authors
to be actually representative either of ancestral plasmas (Weismann)
or of the actual body-cells of the parent (Darwin, Galton, Brooks,
Hallez), or of elementary characteristics and functions of the
organism (Nageli. Kolliker, de Vries, O. Hertwig), or at the same
time of both body-parts and elementary characteristics (Weismann's
latest theory).

Buffon's theory assumed that "the substance of which organisms
are composed differs essentially from that which composes the

Buffon'g inorganic bodies. Organisms are composed of special

theory. particles, the organic molecules. These molecules are

universal and indestructible: universal in that they exist everywhere
where life has access, indestructible in that death and the dissolution
which follows destroy the organisms, break down the molecular com-
binations which constitute them, but do not reach the molecules
themselves. These are only separated, put at liberty, but remain
ready to enter into new groupings. While they cannot be de-
stroyed, neither do they increase in numbers. They form nothing
actually new, either spontaneously, or by means of old ones, so
that, measured by these organic molecules, the total quantity of life
in the universe is invariable" (Delage). Nearly a hundred years
later Bechamp (1883) proposed a theory similar to Buffon's in
which he assumed the composition of organisms out of minute
elementary living particles called microsymes. Like Buffon's
organic molecules they are indestructible, and they are strewed in
innumerable numbers through earth, air, and water. They owe their
origin to special creation by God.

Of the non-immortal kind of micromeres Spencer's physiological
units represent a general type favoured by numerous theorists :
namely, living units all of the same nature and active because of
their polarity, their form and molecular forces, or their vibratory
motion. Spencer's physiological units are active because of their
polarity, but the annular atoms of Dolbear's theory and the
plastidules of the slightly varying theories of Haeckel, His, Cope,
and others, owe their active properties to their vibratory motion.
According to Spencer (1864), there exist between the cells

(morphological life-units) and the molecules which compose them



OTHER THEORIES OF SPECIES-FORMING. 217

(chemical units), units of a third order (physiological units) com-
Spencer's posed of groups of molecules. These units are very

theory, small but very complex, and are the smallest masses in

which living substance can occur. Most of the micromeric theories,
which come after Spencer's, adopt this conception of a life-unit, very
small, but composed of an aggregate of molecules, and therefore
very complex. To his physiological units Spencer attributed a
polarity, wholly analogous with that possessed by the molecules
of Crystalline substances. It is owing to this delicate, precise
polarity, varying of course with the varying molecular consti-
tution of the units, that they possess the capacity of actively
arranging themselves in the varied groupings normal to the parts
of the organisms. "Thus the resemblance is perfect between the
chemical polarity which causes crystallisation and that of the
physiological units which produces the form of organisms. In one
case the chemical molecules group themselves in a manner to form
an aggregate of definite but simple form, cubical, prismatic,
rhomboidal, with their parts arranged en tremies, aiguilles, croix
de Saint Andre, boules epineuses, etc. In the other the units group
themselves in a body of a form less rigorously defined but which
may be very complicated : such as a plant or an animal." (Delage.)

Of the theories in which the living units are assumed to be of
different kinds, and endowed with different functions, some assume
the units to be not directly representative of different cells or parts
of the body, while others assume this truly representative condition.
Of the first sort are a number of theories like those of Berthold,
Geddes, and others, in which the units are taken to be actual
chemical molecules, endowed with activity through special physico-
chemical properties or through purely chemical ones, while still
others keep to the more usual type of a unit of a higher order
than a molecule, in which case also this unit is looked on as spe-
cially active because of particular electrical (Fol) or chemical
(Altmann and Maggi) or vital (Wiesner) endowment. But all of
these theories are much like each other and are much like Spencer's
theory in regard at least to the assumed units. Different, how-
ever, is the type of theory which introduces the assumption that
the fundamental life-units are directly representative of either
the specific cells, parts, or elementary characteristics of the organ-
ism. This is the kind of unit especially favoured by the men
who had, in their formation of a theory, a special eye to the
problem of heredity. How is the single germ-cell to be the bearer
of the "heredity" of the organism from which it comes? what
more simple to assume than that this cell shall be composed of
minute particles gathered from all the cells or groups of similar



3i8 DARWINISM TO-DAY.

cells of the body of the parent? And that is precisely the charac-
teristic assumption, dressed up in an ingenious variety of form,
which charac.erises the theories of life-units most favoured at
present : such theories are those of Darwin, Gallon, Brooks, Nageli,
de Vries, Hertwig, and Weismann. In some of these, interesting
attempts are introduced to connect the assumed structure with
the actually observed finer structure of the nuclear protoplasm, by
introducing combinations of the fundamental units, in one or two,
or even three, successive degrees until an aggregation is reached
which corresponds with those microscopic structures, the chromo-
somes, or chromatin granules or threads, which are actually visible
to the microscope-aided eye. The most recent one of the theories
of this general type is that of Weismann's biophors and determi-
nants structure of the germ-plasm, already explained in connection
with the presentation of his theory of germinal selection (see pp.
193 ff.). As other examples we may note especially Darwin's,
called the theory of the pangenesis of gemmules; and Nageli's,
called the theory of micellae and idioplasm.

Darwin's gemmules are extremely minute particles, which are
formed in all the various cells of the body and are capable of repro-
Darwin's ducing themselves rapidly and in great numbers by

theory, repeated division, and which, by virtue of their minute

size and an innate activity due to a sort of affinity or attraction exist-
ing between them and other substances, move about freely in the body,
penetrating any membranes, and arranging themselves with a deli-
cate precision just where they are most needed. When a gemmule
enters an undifferentiated or developing cell as yet containing no
other gemmules, it controls the development of that cell so that it
becomes a cell of the type from which the gemmule had birth, each
gemmule representing thus exactly the characteristics and the type
of its mother cell. Thanks to the delicate and precise adjustment
of affinities, migrating gemmules only enter those cells which they
really should enter in order that a normal development of all the
cells of the body should go on. But those few cells of the body
which are destined to become germ-cells, that is the spermatozoids
and eggs in animals, the pollen grains and ovules in plants, receive
during their formation gemmules from all the other cells of the
body. Not only from all the cells of the fully developed body, but
from all those ephemeral cells which arise and live for a while
during the ontogeny of the parent, performing certain special func-
tions and then making way for the definitive cells of the mature
organism. Thus in the germ-cells are stored actual physical repre-
sentatives of all the cells which have existed during the whole life
of the parent body. These innumerable gemmules remain inactive



OTHER THEORIES OF SPECIES-FORMING. 219

in the germ-cells until, after fertilisation, the egg-cell begins its
development. Then as the cells of the new organism begin to be
produced, the gemmules become active and each one moves into
the cell it should control and there directs its further development
into precisely the kind of cell it should be at precisely the time it
should be this kind of cell, until there results from this gemmule-
controlled development a photographic reproduction of the parent
body.

frageli's conception is that when the complex life-characterising al-
buminous substances took their birth in an aqueous liquid, they would

Nageli's be precipitated, as they are not soluble in water. This

theory. precipitate is formed of small masses, a sort of organic

crystals, which may be called micella:. And just as an inorganic
crystal deposited in a saturated saline solution of the same nature
determines the deposit on its surface of the dissolved molecules in
the form of little crystals, and by this means grows, so wherever
any micellae are formed they facilitate within their sphere of influ-
ence the precipitation of others, so that this production of micellae
instead of taking place miscellaneously through the liquid will be
localised at certain points. Thus arise aggregates of albuminous
substance, in the condition of micellae, forming the primitive
protoplasm. The micellae, although insoluble in water, have a great
affinity for it, and each one at the time of its precipitation fixes
around itself a thin layer of water, at least as thick as a water
molecule. Thus, all the micellae grouped together in a bit of primi-
tive protoplasm are separated from each other, and also held to-
gether by a layer of water as thick as two water molecules. This
water forms an integral part of the protoplasm. By virtue of it, an
aggregate of albuminous micellae can increase by intercalcation as
well as by the addition of new micellae on the outer surface. By
admitting more or less water the protoplasmic mass may become
more or less nearly fluid. Thus are accounted for the Various
densities always met with in the different parts of a protoplasmic
cell.

A further essential part of Nageli's theory is an arrangement of
the primitive protoplasm in two ways, resulting in two kinds of it,
which are called nutritive plasm and idioplasm respectively. This
arrangement depends on the molecular forces pertaining to the
micellae, and the difference, resulting in two kinds of plasm, depends
upon the relative situation of the micellae composing the mass, just
"how this affects them differently, however, not being made very clear.
But the differentiation is very important, for it is the idioplasm
alone which contains the essential life-properties and which really
gives rise to life with all its variety and complexity. This idioplasm



220 DARWINISM TO-DAY.

is formed at first in scattered bits in the nutritive plasm mass, but
as these bits increase they join and become united into a network
surrounded by and containing in its meshes the nutritive plasm.
And one of the most interesting parts of Nageli's hypothesis is that
he conceives this network of idioplasm not to be limited by cell
boundaries but to penetrate from one cell into adjacent cells and
thus to spread through and unite in a most significant and important
way all the cells and tissues of the body. It is just this sort
of a ramifying, stimulus-carrying, protoplasmic network connect-
ing all the parts of the body that the believers in the inheritance
of acquired characters seem to need as a mechanism to transmit
from soma to germ-cells the effects of external and functional
stimuli.

Next, the theory of intra-cellular pangenesis of de Vries may
be briefly stated. This theory has become the more important be-
cause of the great interest aroused by and the large appreciation
given to the mutations theory of species-forming of the same
biologist. De Vries's theory of intra-cellular pangenesis has much
in common with Darwin's theory of the pangenesis of gemmules,
but it is able to do away with that particularly weak part of Dar-
win's theory, which postulated the circulation of the gemmules
throughout the organism in order that they should meet in the
germ-cells and modify these cells in a parallel way with the modi-
fications occurring in the peripheral organs. Darwin had to postu-
late this circulation of the gemmules through the organism in order
to explain the phenomena of regeneration, and the heredity of.
acquired characters. Now that the heredity of acquired characters
has been shown to be at best an extremely doubtful phenomenon,
and that regeneration is explicable by other means, de Vries has



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 20 of 38)