354 SUMMAEY OF CURRENT RESEARCHES RELATING TO 



SUMMAEY 



OP CUREENT BESEAECHES RELATING TO 



ZOOLOOY AND BOTANY 



(principally Invertehrata and Cryptogamia), 



MICROSCOPY, &c., 



INCLUDING ORIGINAL COMMOTICATIONS FROM FELLOWS AND OTHERS.' 



ZOOLOGY. 



A. GENERAL, including Embryology and Histology 

 of the Vertebrata. 



Contributions to the History of the Constitution of the Ovum.t — 



In this report C.Van Bambeke discusses the relations of the germinal 



Yesicle to the periphery of the yolk. He finds that under the 

 influence of certain reagents, the young ovarian eggs of bony fishes 

 (Leuciscus, Lota) exhibit the presence of a membranous pouch, which 

 incloses the germinal vesicle, and is attached to the periphery of the 

 yolk. In Leuciscus the peripheral portion has the form of a nuclei- 

 form body (vitelline nucleus ?), the long axis of which lies parallel to 

 the surface of the egg. The apparent striation between this nuclei- 

 form body and the germinal vesicle is due to the folds of membrane ; 

 and it is probable that the arrangement described and figured by 

 Schafer as obtaining in the ovarian egg of the rabbit is of the same 

 character. The pouch in question may be considered as a limiting 

 layer, or condensation of the cellular reticulum, which, in the normal 

 state, separates the internal from the external vitellus, to use the 

 nomenclature of Pfliiger ; the nucleiform body will then correspond 

 to the internal yolk. This disposition of parts has perhaps some relation 

 to the maturation and fecundation of the egg, inasmuch as it may be 

 the passage by which the directive corpuscles escape to the exterior, 

 and the fecundating spermatozoon enters to unite with the femalei pro- 

 nucleus. Further researches are necessary to decide whether there 

 is any relation between the division of the yolk into two zones, and 

 the mode in which the yolk-elements are deposited within the egg. 

 The union of the nucleus with the periphery of the cell, which has 



* 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 Bull. Acad. E. Belg., vi. (1883) pp. 813-77 (l^)!.). 



