either case.

It may be mentioned here that owing to the fact that the single (left)
ovary in birds is very closely attached to the peritoneum immediately
covering the great post-caval vein, it is generally impossible to remove
the whole of the ovary without cutting or tearing the wall of the vein and
so causing fatal hemorrhage. The above results observed by Goodale are
therefore all the more remarkable, and it may be assumed that he removed
at any rate nearly all the ovary.

The research of Seligmann and Shattock [Footnote: Relation between
Seasonal Assumption of the Eclipse Plumage in the Mallard _(Anas boscas_)
and the Functions of the Testicle.' _Proc. Zool. Soc._ 1914.] begins with
a comparison between the stages of the development of the nuptial plumage
and the stages of spermatogenesis. In the young pheasant the male plumage
is fully developed in the autumn of its first year, but no pairing occurs
and no sexual instinct is exhibited till the following spring. The wild
duck pairs in autumn or early winter, after the assumption of the nuptial
plumage, but copulation does not occur till spring is advanced. The
investigation here considered was made upon specimens of semi-domesticated
_Anas boscas_, such as are kept in London parks and supplied from game
farms. The testes attain their maximum size during the breeding season--
end of March or beginning of April. At this time each organ is almost as
large as a pigeon's egg, is very soft, and the liquid exuding from it when
cut is swarming with spermatozoa. The bird is of course in full nuptial
plumage. By the end of May, although the plumage is unchanged, the testes
have diminished to the size of a haricot bean, and spermatogenesis has
ceased. They diminish still further during June, July, and August, and
acquire a yellow or brownish colour, while microscopically there is no
sign of activity in the spermatic cells. The change from nuptial plumage