42 Sterile and Hybrid Pheasants 



with a good deal of stroma and fibrous tissue (Figs. 4 and 5, Plate I). 

 In places small cysts could be seen surrounded with a fibrous capsule 

 and containing a fatty fluid (Fig. 5, cy., Plate I). In every respect the 

 sections through this degenerate ovary resemble the Figures 19, 33, 34 

 and 39 given by Prof Poll for the ovaries of duck hybrids (1). 



This bird was otherwise peculiar in that the body was laden with 

 subcutaneous and visceral fat to an extraordinary extent, and also in 

 possessing two very large hyperfcrophied oviducts. 



The second Reeve's x Formosan female {G) showed a very striking 

 assumption of male plumage, both in pattern and colour of the neck, 

 breast, interscapular and tail feathers. The ovary was still more 

 degenerate in structure than in the foregoing, consisting of some 

 minute nodules about 1 mm. across, which showed the same histological 

 structure as the other female. The oviduct in this female was very 

 small and undeveloped. It may be noted that all the sterile females 

 were of an unusually large size, a character which may be regarded as 

 a male one. 



The histological structure of the degenerate ovaries of these 

 females agrees in every way with the excellent descriptions which 

 Prof Poll has given for hybrid ducks ; we see the same inability of the 

 oocytes to grow normally, and the consequent composition of the ovary 

 by interstitial, stroma and fibrous cells. 



The interesting enquiry, which is not answered by Prof Poll, is to 

 determine whether the degeneration of the ova can be ascribed to the 

 same cause as that of the spermatozoa, viz. to the inability of the 

 chromosomes to go through the synaptic phases. At first sight such 

 an interpretation seems absurd, since degeneration of the ova occurs in 

 these hybrids long before polar-body formation when the maturation 

 divisions take place. But as I pointed out in a footnote in a previous 

 paper (Q. J. M. S. Vol. LViii. p. 166), there is evidence that in the 

 female sex a precocious temporary synapsis occurs in the young germ- 

 cells before growth of the oocytes begins, and that this may take place 

 in the quite young organism or even in the embryo. Since the publica- 

 tion of the above-mentioned paper, Mr Jenkinson has collected a great 

 deal of information on this point, and it seems clear that in the female 

 sex throughout the animal kingdom this temporary synapsis of the 

 chromosomes in the young oocytes before growth begins is of universal 

 occurrence. Furthermore Mr A. D. Sprunt has worked through the 

 early stages of developement of the ovary in the chick (Gallns), and he 

 finds that the typical synaptic phases occur in the embryonic ovary 



