the theory (the
struggle for existence and its corollaries) and the accessory Lamarckian
elements. Through these and other controversies the present state of the
question has emerged.

The main antithesis at present is the following. On the one side, the
"all-sufficiency of natural selection" is maintained, that is, progressive
evolution is regarded as coming about without direct self-exertion on the
part of the organisms themselves, simply through the fact that fortuitous
variations are continually presenting themselves, and are being selected
and established according to their utility in the struggle for existence.
On the other side--with Lamarck--the progress is regarded as due to effort
and function on the part of the organism itself. (Increased use of an
organ strengthens it; a changed use transforms it; disuse causes it to
degenerate. Thus new characters appear, old ones pass away, and in the
course of thousands of years the manifold diversity of the forms of life
has been brought about.)

Further, by those of the one side variation is regarded as occurring by
the smallest steps that could have selective value in the struggle for
existence. To the others variation seems to have taken place by leaps and
bounds, with relatively sudden transformations of the functional and
structural equilibrium on a large scale. In regard to these the _role_ of
the struggle for existence must be merely subsidiary. This saltatory kind
of evolution-process is called "halmatogenesis," or, more neatly,
"kaleidoscopic variation," because, as the pictures in a kaleidoscope
change not gradually but by a sudden leap to an essentially new pattern,
so also do the forms of life. Associated with this is the following
contrast. One side believes in free and independent variation of any
organ, any part, any function, physical or mental, any instinct, and so
on, apart from change or persistence in the rest of the organism; the
other side believes in the close connectedness of every part with the
whole, in the strict "correlation" of all parts, in variation in one part
being always simultaneously associated with variation in many other parts,
all being comprised in the "whole," which is above and before all the
parts and determines them. And further, to one school variation seems
without plan in all directions, simply plus or minus on either side of a
mean; to the other, variation seems predetermined and in a definite
direction--an "orthogenesis,"