366 



SUMMARY OF CURRENT RESEARCHES 



RELATING TO 



ZOOLOGY AND BOTANY 



(principally invertebrata and cryptogamia), 



MICEOSCOPY, Etc.* 



ZOOLOGY. 



VERTEBRATA. 



a. Embryolog-y. f 



Transition of Peritoneal Epithelial Cells into Germ-cells in 

 some Amphibians.^ — J- Bronte Gatenby bas studied the ovaries of 

 frogs and toads throughout the year, and maintains that the epithelium 

 surrounding the ovary is truly germinal. During life very large 

 reinforcements of germ-cells arise in the epithelium of the gonad, and 

 transition stages between peritoneal cell and germ-cell are figured. 

 Germ-thickenings in the peritoneal epithelium surrounding the ovary 

 appear in early spring. They become ovariform germ-pockets 

 containing newly formed germ-cells in all stages. 



The intermediate stages between peritoneal cell and germ-cell 

 consist primarily in the elimination of a greater part of the chromatic 

 matter of the nucleus, in the appearance of a granular zone in the 

 cytoplasm which Ijecomes totally granular and stains more heavily than 

 before, and finally in the appearance of several nucleoli subsequent upon 

 a loss of the regular shape of the nucleus. 



Thickenings containing many thousands of germ-cells, and larger 

 than the entire ovary of a lately metamorphosed frog, have been found, 

 especially in May. Reasons are given why the cells composing the 

 germ-thickenings in the ovary are not to be considered stored-up 

 germ-cells. 



The ovary of a tadpole is formed of (1) germ-cells of peritoneal 



* 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 anj- 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, Eeproduction, and 

 allied subjects. 



X Quart. Joum. Micr. Sci., Ixi. (1916) pp. 275-300 (2 pis. and 5 figs.). 



