known utility whatever, so that the problem presented by these characters
was not explained by any theory of the origin of adaptations.

Mendelism, since 1900, has studied experimentally the transmission of
definite characters, and maintains that the characters of species are of
the same nature as the characters which segregate in Mendelian
experiments. Such characters are not in any way related to external
conditions, and cannot, therefore, be adaptive except by accident.
Professor Bateson goes so far as to admit that such large variations or
mutations offer more definite material to selection than minute variations
too small to make any important difference in survival, but as regards
species the important factor is the occurrence of mutations which are
inherited and at once form a distinct definite difference between allied
species which is not due to selection and has nothing to do with
adaptation.

In a book entitled _Problems of Genetics_, 1913, Bateson describes several
particular cases which show how impossible it is to find any relation at
all between the diagnostic characters of certain species or local forms
and their mode of life. One of these cases is that of the species of
_Colaptes_, a genus of Woodpeckers in North America, of which a detailed
study was published in the _Bull. Am. Mus. Nat. Hist._, 1892. The two
forms specially considered are named _C. auratus_ and _C. cafer_, and they
differ in the following seven characters:--


_C. auratus._ _C. cafer._

1. Quills yellow. 1. Quills red.