election of such differences, when
beneficial to the individual, that gives rise to all the more important
modifications of structure which the innumerable beings on the face of
the earth are enabled to struggle with each other, and the best adapted
to survive."

We have dwelt at length upon this subject, because of its great general
importance, and because we believe that Professor Kolliker's criticisms
on this head are based upon a misapprehension of Mr. Darwin's
views--substantially they appear to us to coincide with his own. The
other objections which Professor Kolliker enumerates and discusses are
the following [3]:--

"1. No transitional forms between existing species are known; and
known varieties, whether selected or spontaneous, never go so far as to
establish new species."

To this Professor Kolliker appears to attach some weight. He makes the
suggestion that the short-faced tumbler pigeon may be a pathological
product.

"2. No transitional forms of animals are met with among the organic
remains of earlier epochs."

Upon this, Professor Kolliker remarks that the absence of transitional
forms in the fossil world, though not necessarily fatal to Darwin's
views, weakens his case.

"3. The struggle for existence does not take place."

To this objection, urged by Pelzeln, Kolliker, very justly, attaches no
weight.

"4. A tendency of organisms to give rise to useful varieties, and a
natural selection, do not exist.

"The varieties which are found arise in consequence of manifold external
influences, and it is not obvious why they all, or partially, should be
particularly useful. Each animal suffices for its own ends, is perfect
of its kind, and needs no further development. Should, however, a
variety be useful and even maintain itself, there is no obvious
reason why it should change any further. The whole conception of the
imperfection of organisms and the necessity of their becoming perfected
is plainly the weakest side of Darwin's Theory, and a 'pis aller'
(Nothbehelf) because Darwin could think of no other principle by which
to explain the metamorphoses which, as I also believe, have occurred."

Here again we must venture to dissent completely from Professor
Kolliker's conception of Mr. Darwin's hypothesis. It appears to us to be
one of the many peculiar merits of that hypothesis that it involves no
belief in a necessary and continual progress of organisms.

Again, Mr. Darwin, if we read him aright