SUMMARY OF CURRENT RESEARCHES 



RELATING TO 



ZOOLOGY AND BOTANY 



(principally invkrtkbrata and cryptogamia), 



MICROSCOPY, Etc.* 



ZOOLOGY. 



VERTEBRATA. 

 «• Embryology. f 



Oogenesis in Cat.J — Huns von Winiwarter and G. Sainmoint find 

 that the definitive ova are all formed after the fa-tal period. All the 

 medullary formations and all the ova and follicles of the primitive 

 cortical layer disappear. The definitive ova arise either from non- 

 differentiated cells of the second proliferation (tubes of Pfliiger), or 

 from cells of the third proliferation or epithelial invagination. This 

 ueo-f ovulation is the only one that occuvs in the course of the develop- 

 ment of the ovary. 



Origin of Primitive Germ-cells in Rana esculenta.§ — Sergius 

 Kuschakewitsch finds that in a normal brood the primitive germ-cells 

 arise from two sources. There are some of primary origin from modi- 

 fied yolk -cells ; there are others of secondary origin — from mesenchyme 

 and ccelomic epithelium. In embryos which develop from lute- 

 fertilised eggs there is no stage of primary germ-cells, and the pri- 

 mordium of the gonad cannot become an ovary. It becomes a testis, 

 and the spermatogonia appear directly from the geuital strands. 



Entrance of Dogfish Ovum into the Oviduct.|| — V. Widakowich 



discusses this question, and finds a solution in the alterations of pressure 

 brought about by the changes in the hepatic venous- sinus and tube- 

 sinus which lies around the ostium abdominale tubarum and the 

 beginning of the oviducts. 



* 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 arc 

 either new or have not been previously described in this count i \ . 



t This section includes not only "papers relating to Embryology properly so 

 called, but also those dealing with Evolution, Development, Reproduction, and 

 allied subjects. J Acad. R. Belg. Classe des Sci., 1908, No. 6, pp. 602 7. 



§ SB. k. Akad. wiss. Miinchen, 1908, pp. 89-101 (11 figs.). 



|| Zeitschr. wiss. Zool., xci. (1908) pp. 640-58 (1 pi., 2 figs). 



