334 SUMMAPA'' OF CURRENT RESEARCHES RELATING TO 



sixty cases. He finds that the supplying ovary has no influence upon 

 the sex of the child, and that male and female children result in about 

 equal numbers from the fertilization of ova from either ovary. He 

 concludes that " the causation of sex is probably not due to any factor 

 in the unfertilized ovum, that the ' chromosome theory ' must be 

 considered the only explanation of the causation of sex at present 

 acceptable, and that the sex of an unborn child cannot be foretold, noi* 

 can either sex be produced at will, by any rules known at present." 



J. A. T. 



Correlation between Pigeon's Crop and Gonads. — Ch. Champy and 

 P. CoLLE (Gomptes Rendus Soc. Biol., Paris, 82, 1919, 818-9). During 

 incubation the mucous membrane of the crop of both sexes thickens 

 greatly, and continues to secrete for fifteen days after the eggs are 

 hatched. The reduction in the size of the testes from the beginning 

 of incubation onwards coincides with the multiplication of cells in the 

 lining of the crop. The testes begin to return to their normal size 

 from about the middle of the incubation period. There is an arrest of 

 spermatogenesis and an absorption of more than half of the seminiferous 

 tubules. There is no noteworthy development of interstitial tissue as is 

 seen during the quite different winter regression. The spermatogenesis 

 recommences some five or six days after the hatching of the eggs. In 

 the female there is during incubation an atresia of numerous oocytes of 

 large size ; the maximum of this, which is quite different from the 

 winter arrest of oogenesis, is towards the middle of the incubation 

 period. It must be noted that some atresia occurs outside the incuba- 

 tion period altogether, but it is not so marked. It seems then that 

 during the exaggerated glandular development of the crop there is an 

 intense absorption of germ-cells in the gonads. This probably illustrates 

 a nutritive balance ; but the regression of the gonads does not continue 

 during the whole secretory activity of the crop, and there is no trace of 

 any hormone. J. A. T. 



h. Histology. 



Minute Structure of Membranous Labyrinth of Tadpoles. — Take- 

 SHIRO ASAI {MT. Med. Fak. Univ., Tokyo, 1918, 19, 315-88, 2 pis.). 

 An elaborate study of the tadpoles of Bufo vidgaris and Rana esculenta 

 as regards the minute structure of the membranous labyrinth, and with 

 special reference to the nerve-endings in the epithelium of the pars 

 neglecta. The investigation deals first with the •otolithic mass and the 

 so-called covering membrane (over the epithelial surface of the macula), 

 and the latter is shown to be non-existent. Next comes a description 

 of the areas of nerve endings in the membranous labyrinth, and of the 

 different kinds of cells. The basal-cells and the thread-cells of the 

 crista and macula acustica are dealt with, and then the hair-cells and 

 the auditory hairs. Subsequent sections discuss the cupula terminalis, 

 the utriculo- saccular foramen, the pars neglecta, the membrana tectoria, 

 and the crista acustica. We can only indicate the parts dealt with. 



J. A. T. 



