SUMMARY OF CURRENT RESEARCHES 



RKLATINO TO 



ZOOLOGY AND BOTANY 



(PRINCIPALLY INVERTEBRATA AND CRYPTOGAMIA), 



MICROSCOPY, Etc.* 



ZOOLOGY. 



VERTEBRATA. 



a. Embryology. t 



Russo's attempt to show Differentiation of Sex in Ovarian Ova 

 of Rabbit.} — Walter Heape directs attention to Russo's recent work, 

 in which he seeks to show : (1) that by means of the introduction of 

 lecithin into the doe rabbit he can profoundly modify the proportion 

 of the sexes produced by her ; and (2) that he can thereby also demon- 

 strate histologically two kinds of ovarian ova, "male" and "female" 

 ova. It seems that of the two " male " ova figured by Russo, one is in 

 a degenerating follicle and the other in a state like an early phase of 

 degeneration. Heape is forced to deny the cogency of Russo's alleged 

 demonstration, but he is strongly of opinion that the quality or quantity 

 of food supplied to the mother, and her individual capacity for assimi- 

 lating food and transmitting nutriment to the ovary, under varying 

 conditions of metabolism, are factors of importance in determining the 

 proportion of the sexes ultimately produced by all animals in which 

 only a limited number of their ovarian ova come to maturity. 



Sex of Pheasant Hybrids.§— Michael F. Guyer finds that in a total 

 of sixty-one hybrids of Phasianidas which he studied in museums, the 

 sex was not noted in ten cases, it was male in forty-seven, and female 

 in four (of which three were hybrids of very closely related species). 

 He suggests that the predominance of males may be somehow due to 

 defective nutritive conditions associated with the incompatibility in 

 two germ-plasms which are too dissimilar. 



* The Society are not intended to be denoted by the editorial " we," and they 

 do not hold themselves responsible for the views of the authors of the papers 

 noted, nor for any claim to novelty or otherwise made by them. The object of 

 this part of the Journal is to present a summary of the papers as actually pub- 

 lished, and to describe and illustrate Instruments, Apparatus, etc., which are 

 either new or have not been previously described in this country. 



t This section includes not only papers relating to Embryology properly so 

 called, but also those dealing with Evolution, Development, Keproduction, and 

 allied subjects. % Proc. Cambridge Phil. Soc, xiv. (1908) pp. 609-12. 



§ C.R. Soc. Biol. Paris, lxv. (1908) pp. 642-4. 



