no one has ever been able to suggest a use for it. It has always been
quite impossible to bring it within the scope of the theory of natural
selection. The evolution of it can only be explained either on the theory
of mutation or some Lamarckian hypothesis. The process of dislocation of
the testis does not conform to the conception of mutation, nor agree with
other cases of that phenomenon. A mutation is a change of structure
affecting more or less the whole soma, but showing itself especially in
some particular organ or structure. But I know of no mutation occurring
under observation which consisted, not in a change of structure or
function, but merely in a change of position of an organ from one part of
the body to another, and moreover a change which takes place by a
continuous process in the course of development. If the testes were
developed from the beginning in a different part of the abdomen, there
might be some reason in calling the change a mutation. Moreover, if it is
a mutation, why has it never occurred in any other class of Vertebrates
except Mammals?

In 1903 Dr. W. Woodland published [Footnote: _Proc. Zool. Soc._, 1903,
Part 1.] a Lamarckian theory of this mammalian feature, the probability of
which it seems to me has been increased rather than decreased by the
progress of research concerning heredity and evolution since that date.
Dr. Woodland correlated the dislocation of the testes with the special
mechanical features of the mode of locomotion in Mammalia. His words are:
'The theory here advocated is to the effect that the descent of the testes
in the Mammalia has been produced by the action of mechanical strains
causing rupture of the mesorchial attachments, such strains being due to
the inertia of the organs reacting to the impulsiveness involved in the
activity of the animals composing the group.' The 'impulsiveness' is the
galloping or leaping movement which is characteristic of most Mammals when
moving at their utmost speed, as seen, for example, in horses, deer,