974 SUMMAEY OF CUKBENT KESEARCHE8 RELATING TO 



SUMMAEY 



OF OUEEENT RESEARCHES RELATING TO 



ZOOLOaY AND BOTANY 



(principally Invertebrata and Cryptogamia), 



MICROSCOPY, &c., 



INCLUDING OEIGINAL COMMUNICATIONS FEOM FELLOWS AND OTHERS.* 



ZOOLOGY. 



A. GrENERAL, including Embryology and Histology 

 of the Vertebrata. 



Development of Sexuality. t — As the result of observations on 

 the development of the sex-glands in the higher vertebrates, and 

 especially in birds, M. F. Laulanie seeks to establish a strict paral- 

 lelism between the ontogenetic and phylogenetic history. In the 

 chick he distinguishes three great stages in the development — 

 (1) a period of germiparity, (2) hermaphroditism, (3) differentiated 

 uni sexuality, which he regards as recapitulating the great steps in 

 the historic evolution. 



1. For the first period of germiparity from the fourth to the sixth 

 day the designation " sexual neutrality or indifference " is inappro- 

 priate, since the " cortical ovules " of the germinal epithelium have 

 from the first the precise morphological significance of germs or 

 female elements, and in the female proceed by proliferation to form 

 the ovary, while in the male they degenerate. 



2. In the period of hermaphroditism, beginning with the seventh 

 day, in the male the male elements appear in the form of reticulated 

 cellular strands — the future seminal tubules — arising in the medullary 

 or mesodermal, and not in the cortical layer : with them are associated 

 primordial male ovules, morphologically like the above cortical 

 ovules, but originating in the mesoderm, w^hence they are designated 

 " ovules medullaires." At the same time, but yet distinct, there are 

 seen certain " cortical " (i. e. female) ovules persisting in the germinal 

 epithelium. Similarly in the ovary of the female the medullary 

 layer, strictly separated by a partition of connective tissue from the 

 oviparous layer, contains a large number of medullary (i. e. male or 



* 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 tl:e Journal is to present a summary of the papers as actuaUi/ published, 

 and to describe and illustrate Instruments, Apparatus, &c., which are either new 

 or have not been previously described in this country. 



t Comptes Rendus, ci. (1885) pp. 393-5. 



