female? (2) By what means are these effects brought about, what is the
physiological explanation of the influence of the gonads on the soma?

I have quoted the evidence concerning the effects of castration on stags
in my _Sexual Dimorphism_ and in my paper on the 'Heredity of Secondary
Sexual Characters.' [Footnote: _Archiv fuer Entwicklungesmechanik_, 1908.]
When castration is performed soon after birth a minute, simple spike
antler is developed, only two to four inches in length: it remains covered
with skin, is never shed, and develops no branches. When the operation is
performed on a mature stag with antlers, the latter are shed soon after
the operation, whether they have lost their velvet or not. In the
following season new antlers develop, but these never lose their velvet or
skin and are never shed.


CASTRATION IN FOWLS

The removal of the testes from young cocks has been commonly practised in
many countries, _e.g._ France, capons, as such birds are called, being
fatter and more tender for the table than entire birds. The actual effect,
however, on the secondary sexual characters has not in former times been
very definitely described. The usual descriptions represent the castrated
birds as having rather fuller plumage than the entire birds; but the comb
and wattles are much smaller than in the latter, more similar to those of
a hen. It is stated that the capon will rear chickens, though he does not
incubate, and that they are used in this way in France.

The most precise of the statements on the subject by the earlier
naturalists is that of William Yarrell [Footnote: _Proc. Linn. Soc.,
1857.] (1857), who writes as follows:--