more recent of these is that of a pheasant of the white-ringed Formosan
variety, _P. torquatus_, of the Chinese pheasant. [Footnote: C. J. Bond,
'Unilateral Development of Secondary Male Characters in a Pheasant,'
_Journ. of Genetics_, vol. iii., 1914.] On the left side this bird shows
the plumage, colour, and the spur of the male; on the right leg there is
no spur except the small rudiment normally occurring in the hen. The
difference in plumage between the two sides, however, is not complete. The
white collar is strictly limited to the left side, but the iridescent blue
green of head and neck is present on both sides, though more marked on the
left. Only a few male feathers appear in the wing coverts of the left
side. The breast feathers are rufous, especially on the left side. The
tail coverts show marked male characters, more especially on the left
side. In the tail, however, the barred character of the male is not
present on one side, absent on the other, but in most of the feathers is
confined to one, the _outer_ side of each feather. With regard to the
gonads, in this bird a single organ was found on the left side, _i.e._ in
the position of the ovary in normal females, and there was no trace of a
gonad on the right side. The organ present was small, 3/4 inch long by 1/2
inch broad, and microscopic sections showed in one part actively growing
areas of tubular gland structure in some of which bodies like spermatozoa
could be detected, while in another were fibrous tissue with degenerating
cysts. The latter appear to have been degenerating egg follicles. The
author concludes that the organ was originally a functional ovary, and
that the ovarian portion had atrophied while a male portion had become
functionally active.

Another case in birds was described by Poll [Footnote: _B.B. Ges. Naturf.
Freunde_, Berlin, 1909.] and is mentioned by Doncaster. [Footnote:
_Determination of Sex_, Cambridge, 1914.] It is that of a Bullfinch
which had the male and female plumage sharply separated on the two sides