published in 1903, may be described in large part as theory. They state
that the interstitial cells appear in the male embryo before the
gametocytes present distinctive sex-characters. They conclude that the
interstitial cells supply a nutritive material (hormone?), which has an
effect on the sexual orientation of the primitive generative cells. In
addition to this function, the interstitial cells by their hormone also
give the sexual character to the soma. When castration is carried out at
birth the male somatic characters do not entirely disappear, because the
hormone of the interstitial cells has acted during intrauterine life. The
functional independence between the interstitial cells and the seminal
tubules is shown by the fact that if the vasa deferentia are closed the
seminal gland (_i.e._ tubules) degenerates while the interstitial cells do
not. In the embryo the interstitial gland is large, in the adult
proportionately small.

There is complete disagreement between the results of Ancel and Bouin on
the one hand, and those of Shattock and Seligmann on the other, with
regard to the effects of ligature of the vasa deferentia. The latter
authors, as mentioned above, found that after ligature not only the
somatic characters but the testis itself developed normally. The
experiments were performed on Herdwick sheep and domestic fowls. They
state that on examination the testes were found to be normally developed,
and spermatogenesis was in progress. The experiments of Ancel and Bouin
were carried out on rabbits seven to eight weeks old, and consisted in
removing one testis, and ligaturing the vas deferens of the other. About
six months after the operation the testis left _in situ_ was smaller, the
seminal tubules contained few spermatogonia, though Sertoli's cells (cells
on the walls of the tubules to which the true spermatic cells are
attached) were unchanged; while the interstitial cells were enormously
developed, by compensatory hypertrophy in consequence of the removal of