scrotal sacs.

It might be thought that in this case, although the hormone theory of
heredity might be applied, there was no reason to suppose that a hormone
derived from the testis in the individual development was necessary in
order that the hereditary change should take place. If the individual was
male and therefore had a testis, this organ would by heredity go through
the process of dislocation. But there is the curious fact that when the
descent is not normal and complete, in what is called cryptorchidism, the
organs are always sterile. The retention of the testes within the abdomen
may be regarded as a case of arrested development, like many other
abnormalities, but this does not explain why the retained testes should
always be sterile, without spermatogenesis. If the inherited or congenital
process of dislocation requires the presence of hormones produced by a
normal testis, then we can understand why a defective testis does not
descend completely, because it does not produce the hormone which is
necessary to stimulate the hereditary mechanism to complete dislocation.
It is often stated that in cryptorchidic individuals the sexual instincts
and somatic sexual characters are well developed, which would appear
contradictory to the above explanation, but according to Ancel and Bouin
such individuals in the case of the pig show considerable differences in
the secondary signs of sex and in the external genital organs, presenting
variations which lie between the normal and the castrated animal.

We have here, then, in the position of the testes in Mammalia a condition
which is not in the slightest degree 'adaptive' in the ordinary sense--
that is, fulfilling any special function or utility. The condition must be
regarded as distinctly disadvantageous, since the organs are more exposed
to injury, and the abdominal wall is weakened, as we know from the risk of
scrotal hernia in man. But from the Lamarckian point of view the facts