The Characteristic Features Of Darwinism

We do not propose to expound the Darwinian theory for the hundredth time;

a knowledge of it must be taken for granted. We need only briefly call to

mind the characteristic features and catchwords of the theory as Darwin

founded it, which have also been the starting points of subsequent

modifications and controversies.



All living creatures are bound together in genetic solidarity. Everything

has evolved th ough endless deviations, gradations, and differentiations,

but at the same time by a perfectly continuous process. Variation

continually produced a crop of heterogeneous novelties. The struggle for

existence sifted these out. Heredity fixed and established them. Without

method or plan variations continue to occur (indefinite variations). They

manifest themselves in all manner of minute changes ("fluctuating"

variations). Every part, every function of an organism may be subject

individually to variation and selection. The world is strictly governed by

what is useful. The whole organisation as well as the individual organs

and functions bear the stamp of utility, at least, they must bear it if

the theory is correct. In the general continuity the transitions are

always easy; there are no fundamentally distinct "types," architectural

plans, or groups of forms. Where gaps yawn the intermediate links have

gone amissing. There is no fundamental difference between genus,

species, and variety. Even the most complicated organ such as the eye,

the most puzzling function such as the instinct of the bee, may be

explained as the outcome of many more primitive stages.



The chief evidences of the theory of descent are to be found in

homologies, in the correspondences of organs and functions, as revealed by

comparative anatomy and physiology, in the recapitulation revealed by

embryology, in the structure of parasites, in rudimentary organs and

reversions to earlier stages, in the distribution of animals and plants,

and in the possibility of still transforming, at least to a slight extent,

one species into another, by experimental breeding.



Transformation and differentiation go on in nature as a vast, ceaseless,

but blind process of selection. In artificial selection evolution is

secured by choosing the most fit for breeding purposes; so it is secured

in natural selection by the favouring and survival of those forms which

are the most fit among the many unfit or less fit, which happened to be

exposed to the struggle for existence, that is, to the competition for the

means of subsistence, to the struggle with enemies, to hostile

environment, and to dangers of every kind. The adaptation thus brought

about is of a purely "passive" kind. The variations arise fortuitously out

of the organism, and present themselves for selection in the struggle for

existence; they are not actively acquired by means of the struggle. The

secondary factors of evolution recognised are: correlation in the growth

and in the development of parts, the origin of new characters through use,

their disappearance through disuse (Lamarck), the transmission of

characters thus acquired, the influence of environment and sexual

selection.(5)



The Darwinian theory, the interpretation of the teleological in the

animate world by means of the theory of descent based upon natural

selection, entered like a ferment into the scientific thought-movement,

and in a space of forty years it has itself passed through a series of

stages, differentiations, and transformations which have in part resulted

in the present state of the theory, and have in part anticipated it. These

are represented by the names of workers belonging to a generation which

has for the most part already passed away: Darwin's collaborateurs, such

as Alfred Russel Wallace, who independently and simultaneously expounded

the theory of natural selection, Haeckel and Fritz Mueller, Naegeli and

Askenasy, von Koelliker, Mivart, Romanes and others. The differentiation

and elaboration of Darwin's theories has gone ever farther and farther;

the grades and shades of doctrine held by his disciples are now almost

beyond reckoning.