SUMMARY OF CURRENT RESEARCHES' 



RELATING TO 



ZOOLOGY AND BOTANY 



(PRINCIPALLY INVERTEBRATA AND CRYPTOGAMIA), 



MICEOSCOPY, Etc.* 



ZOOLOGY. 



VERTEBRATA. 



a. Embryology. t 



Origin of Gonocytes in Amphibians.^ — A. P. Dustin has made a 

 study of the origin of the sex-cells in Amphibians, with a view to deter- 

 mining (1) what part of the embryo gives rise to the first rudiment of 

 the sexual organ, and (2) whether the cells of which the primary rudiment 

 is composed go to form, in whole or in part, and with or without the 

 assistance of other elements, the later definite sex-cells. After reviewing 

 the literature on the subject, the investigator describes his researches on 

 Triton alpestris, Ranafusca, and Bufo vulgaris, the larvae of Rana being 

 studied up till the final metamorphosis. He found that the course of 

 development was fundamentally the same in Triton and Rana, but that 

 some stages which were successive in Triton were simultaneous in 

 Rana. His general conclusions are as follows. The first rudiments of 

 the reproductive organs of Amphibians are paired, symmetrical, and of 

 purely mesoblastic origin. These rudiments represent morphologically 

 a part of the primitive ccelom (gonocoele). They do not exhibit rneta- 

 meric arrangement except in the Urodela, where traces of such arrange- 

 ment may be discerned. The unpaired genital rudiment of Amphibians 

 results from the union along the median line of the paired bilateral 

 primordia. The rudiments of the definitive bilateral glands result from 

 the emigration of the cells of the primary rudiment into a peritoneal 

 crest projecting into the ccelom, and ultimately from the localised pro- 

 liferation of the cells of the peritoneal epithelium, forming the crest 

 and investing the primary gonocytes. A certain number of the cells of 



* 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, Reproduction, and 

 allied subjects. X Arch. Biol., xxiii. (1907) pp. 411-522 (2 pis.). 



June 17 th, 1908 Y 



