4 J. BKONTE GATENBY 



gebriiuchlichen Kernfarbstoffen intonsiv farbonden Kiigelchpn, 

 die wohl aus ihm hervorgegangen sind, und die an den Eand 

 des Keimblaschons riickon, um wahrscheinlich aus diesem in 

 das umgebende Plasma auszutreten '. 



Hempelmann recognizes only one sort of plasma granule 

 — 'yolk', originating from tb(^ peri-nuclear ' Tropfchen '. 

 According to him, the entry of additional spermatozoa into 

 the oocyte is prevented by the formation of a membrane ; 

 the spermatogenesis has ])een studied l)y Hempelmann, who 

 descril^ed the tripartite ' Nebenkern ' of the spermatid ; his 

 material was not preserved carefully enough to allow of his 

 giving a good account of the formation of the male gamete. 



Van Gaver and P. Stephan have published two short notes 

 on Saccocirrus papillocercus. In their second 

 paper these observers state, ' Notre desaccord fondamental 

 avec Hempelmann a trait a I'epoque de la penetration du 

 spermatozoide ; pour nous, le spermatozoide arrive dans 

 I'oocyte des que celui-ci est differencie en tant qu'oocyte, 

 lorsque sa taille est encore extremement minime et avant 

 toute formation de vitellus a son interieur. Nous n'osons pas 

 affirmer que Faction du spermatozoide soit la cause initiale 

 du developpement de I'oocyte, mais nous avons constamment 

 trouve un de ces elements dans les ovules en voie d'accroisse- 

 ment et d'elaboration vitelline '. In addition, van Gaver and 

 Stephan believe that polyspermy and assimilation of sperma- 

 tozoa by the cytoplasm take place in Saccocirrus. They find 

 ' desintegration des tetes des spermatozoides et, par suite, 

 leur assimilation par I'oocyte '. The articles of van Gaver 

 and Stephan are not illustrated by figures. 



The latest observer to attack these problems was Paul 

 Buchner (3). He showed that the w^hole tail of the sperm 

 may occasionally enter an oocyte, and break up to give rise 

 to a number of peripheral droplets, while the head of the sperm 

 remains quiescent. The yolk-formation he describes as taking 

 place by a partial breaking up of the nucleolus, pieces of which 

 wander to the periphery of the nucleus — particles of yolk 

 appearing simultaneously, apparently from the nucleolar 



