( 757 ) 

 SUMMARY 



OF CURRENT RESEARCHES RELATING TO 



ZOOLOGY AND BOTANY 



(principally Invertebrate and Cryptogamiu), 



MICROSCOPY, &c, 



INCLUDING ORIGINAL COMMUNICATIONS FROM FELLOWS AND OTHERS.' 



ZOOLOGY. 



A. GENERAL, including Embryology and Histology 

 of the Vertebrata. 



Spermatogenesis in Mammalia.t — G. Benson finds that, when 

 the testicular caualiculi of the rat are treated with osmic acid, the 

 following sets of cells may be made out : (1) Large, rounded cells 

 with large nuclei, the protoplasm containing a number of granulations 

 — these are the seminiferous cells of Sertoli. (2) Multinuclear cysts 

 provided with a variable (4-20) number of nuclei, and varying in form 

 according to their stage of development. Frequently the nuclei are 

 slightly elliptical, an appearance which appears to be the forerunner 

 of their conversion into the heads of the spermatozoa ; in such cysts 

 there is a distinct differentiation of the protoplasm, which has become 

 condensed and limited around each nucleus ; so that, when completely 

 developed, we have rather to do with aggregations of cells than with 

 multinuclear protoplasmic masses. (3) There are also small rounded 

 cells, the nucleus of which presents every stage in the development of 

 the head of the spermatozoa ; these, which, with Sertoli, the author 

 calls nematoblasts, have, like their predecessors, a refractive corpuscle 

 placed near the nucleus. 



The whole series of changes may be thus expressed : a genera- 

 tion of spermatozoa is developed, and expelled into the lumen of the 

 canaliculus ; the seminiferous cells multiply to form a new genera- 

 tion of nematoblasts ; germ-cells are developed from a peripheral 

 protoplasmic plexus which takes on the characters and situation 

 of the seminiferous cells ; a new generation of germ-cells is developed 

 in the outer portion of the canaliculus. The author has not been able 

 to determine the origin of these germ-cells. The result of following 



* The Society are not to be considered responsible for the views of the 

 authors of the papers referred to, nor for the manner in which those views 

 may be expressed, the main object of this part of the Journal being to present a 

 summary of the papers as actually published, so as to provide the Fellows with 

 a guide to the additions made from time to time to the Library. Objections and 

 corrections should therefore, for the most part, be addressed to the authors. 

 (The Society are not intended to be denoted by the editorial " we.") 



t Arch, de Biol., iii. (1SS2) pp. 291-334 (2 pis.). 



