course of pregnancy. According to these authors numberless instances prove
that in women double ovariotomy does not necessarily interfere with the
course of pregnancy or the development of the milk glands. Parturition may
take place and be followed by normal lactation. This shows that a hormone
from the corpora lutea is not necessary either to the uterus or the milk
glands, at any rate in the last third of pregnancy, though of course this
does not prove that such a hormone is not necessary for the earlier stages
both of pregnancy and growth of the milk glands.

The results of Steinach, if confirmed, would prove conclusively that the
ovaries and testes produce hormones which determine the development of all
the sexual characters, not merely physical but psychical. He adopts the
view that the interstitial cells or gland are the source of the active
hormone. He claims by transplantation of the gonads in young rats and
guinea-pigs to have feminised males and masculised females. The females
are smaller, and hare finer, softer hair than the males. The testes were
removed and ovaries implanted in young males. The animals so treated grew
less than the merely castrated specimens, and therefore when full-grown
resembled females in size. In the young state both sexes have fine, soft
hair, the feminised males had the same character, like the normal females.
They also developed teats and milk glands like the females, and were
sought and treated as females by the normal males. When the implanted
ovaries are able to resist the influence of their new surroundings, the
female interstitial gland, which Steinach calls the puberty gland,
develops so much that an intensification of the female character takes
place: the animals are smaller than normal females, the milk glands
develop and secrete milk, which can be easily pressed out, and if young
are given to them they suckle them and show all the maternal instincts.

Why the ovary in normal circumstances only when in the gravid condition