SUMMARY OF CUPiRENT EESEAECHES 



RELATING TO 



ZOOLOGY AND BOTANY 



(PEINCIPALLY INVERTEBEATA AND CRYPTOGAMIA) 



MICROS C O P Y, Etc.* 



ZOOLOGY. 



VERTEBR ATA. 



a. Embryolog-y.f 



Origin of Zona Pellucida of Mammalian Ovum.| — Jan Tur brings 

 forward arguments, from teratology and pathology, in favour of the view 

 that the zona pellucida is wholly due to the ovum and not follicular. 

 He refers, for instance, to the occurrence in a cat's ovary of two united 

 ova surrounded by a common zona pellucida, and to the absence of a 

 zona pellucida in an enfeebled ovum in follicles with three or four ova. 



Spermatogenesis of the Bat.§ — H. E. Jordan discusses the con- 

 traction phase or synizesis in the spermatocytes. It is the result of an 

 active polarization process of the nuclear reticulum. The idiozome 

 probably plays an accessory role in bringing it about. Sinizesis and 

 chromosome reduction are coincident processes ; the latter occurs by 

 parasynapsis. The resting primary spermatocyte contains a bipartite 

 chromatin (chromosome) nucleolus, which can be traced through synapsis 

 to early prophase. Henceforth it becomes indistinguishable by form or 

 behaviour from the ordinary chromosomes. 



Spermatogenesis in Man.|l — Hans von Winiwarter has studied in 

 particular the cells of Sertoli and the occurrence of a heterochromosome. 

 He maintains that the cells of Sertoli are individual elements, not form- 

 ing a syncytium ; that they and the spermatogonia have a common 

 origin ; that in their adult state they do not show either karyokinesis or 

 amitosis, though the latter may occur as an anomaly. He finds definite 

 evidence of a heterochromosome in the spermatocytes. Some spermatids 



* 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 

 published, 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. 



t G.R. Soc. Biol., Ixxii. (1912) pp. 336-7. 



§ Anat. Anzieg., xl. (1912) pp. 513-22 (24 figs.). 



II Arch. Biol., xxvii. (1912) pp. 91-189 (2 pis.). 



