d into the castrated frogs it exerted an
elective action on the sexual reflex, sometimes in a few hours,
but the action is, Steinach concludes, first central. The
testicular secretion of frogs that were not sexually active had
no stimulating action, but if the frogs were sexually active the
injection of their central nervous substance was as effective as
their testicular substance. In either case, Steinach concludes,
there is the removal of an inhibition which is in operation at
sexually quiescent periods.

Speaking generally, Steinach considers that there is a process of
"erotisation" (Erotisieurung) of the nervous center under the
influence of the internal testicular secretions, and that this
persists even when the primary physical stimulus has been
removed.

The experience of veterinary surgeons also shows that the sexual impulse
tends to persist in animals after castration. Thus the ox and the gelding
make frequent efforts to copulate with females in heat. In some cases, at
all events in the case of the horse, castrated animals remain potent, and
are even abnormally ardent, although impregnation cannot, of course,
result.[8]

The results obtained by scientific experiment and veterinary experience on
the lower animals are confirmed by observation of various groups of
phenomena in the human species. There can be no doubt that castrated men
may still possess sexual impulses. This has been noted by observers in
various countries in which eunuchs are made and employed.[9]

It is important to remember that there are different degrees of
castration, for in current language these are seldom
distinguished. The Romans recognized four different degrees: 1.
True _castrati_, from whom both the testicles and the penis had
been removed. 2. _Spadones_, from whom the testicles only had
been removed; this was the most common practice. 3. _Thlibiae_, in
whom the testicles had not been removed, but destroyed by
crushing; this practice is referred to by Hippocrates. 4.
_Thlasiae_, in whom the spermatic cord had simply been cut.
Millant, from whose Paris thesis (_Castration Criminelle et
Maniaque_, 1902) I take these definitions, points out that it was
recognized that _spadones_ remained apt for coitus if the
operation was performed after puberty, a fact appreciated by many
Roman ladies, _ad seouras libidinationes_, as St. Jer