The Nebenkern in the spermatogenesis of Pulmonata — Helix and Arion. 437 



given in the former publication ^) and that in the memoir under con- 

 sideration. In the earlier paper the asters are described as being 

 formed at a late period around the polar funnels ("entonnoirs polaires"), 

 these latter being fibrillar portions of nuclear substance which have 

 been extruded through pores in the nuclear membrane, 1. c. p. 237. 

 In the more recent paper in discussing on p. 233 the arrangement of 

 the chromosomes into two groups, one in the vicinity of each aster 

 the autor speaks as if the asters were formed first and then had 

 superadded to them the polar funnels. Thus on p. 234 we read: 

 "Je crois .... qu'il y a un moment peu après l'établissement des 

 asters où les chromosomes se présentent en un ou deux groupes au 



voisinage immédiat des deux asters ou de l'un d'eux Je 



soupçonne qu'à ce moment il s'établit à chaque pôle du noyau un 

 pore par lequel le noyau est mis en communication ouverte avec le 

 cytoplasme: que par ces pores le noyau déverse une substance mi- 

 liquide dans le corps de la cellule, substance qui y forme les enton- 

 noirs polaires etc." 



But if the polar funnels are formed after the asters, what is the 

 cause of the appearance of the latter? A return to the old well- 

 established point of view seems inevitable. As to the point of fact 

 whether the radiations have any influence on the position of the chromo- 

 somes prior to the resolution of the nuclear membrane, I have not a 

 sufficient number of observations on which to found an authoritative 

 opinion. 



I have little to remark about the spermatocytes II. The peculiar 

 glassy appearance which osmic acid gives to the chromosomes renders 

 their analysis very difficult and I have little doubt that if Lee had 

 used Perenyi material as a control he would have easily found such 

 figures as those appended to the present paper. Whether these in- 

 dicate a longitudinal splitting in the morphological sense or not is 

 difficult or impossible to determine as the analysis of the metakineses 

 and anaphases of the first ripening division is extremely difficult. 



It is needless to undertake an exhaustive review of the conclud- 

 ing chapters which deal with theoretical conclusions. These, for the 

 most part, depend on the non-existence of centrosomes and on the 

 absence of a numerical reduction in the spermatogenetic series. The 

 first of these premises is untenable and the second far from secure. 



Lee considers the cytoplasm of the spermatocytes I as made u]) 



1) Sur le Nebenkern etc., in: La Cellule, V. 11. 



