varieties, whether selected or spontaneous, never go so far
as to establish new species."

To this Professor Koelliker 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 Koelliker 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, Koelliker, 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
Koelliker'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, assumes no special tendency of
organisms to give rise to useful varieties, and knows nothing of needs
of development, or necessity of perfection. What he says is, in
substance: All organisms vary. It is in the highest degree improbable
that any given variety should have exactly the same relations to
surrounding conditions as the parent stock. In that case it is either
better fitted (when the variation may be called useful), or worse
fitted, to cope with them. If better, it will tend to supplant the
parent stock; if worse, it will tend to be extinguished by the parent
stock.

If (as is hardly conceivable) t