1908] YAMANOUCHI— SPERMATOGENESIS AND OOGENESIS 159 



The disintegration takes place in the body of the sperm in the very 

 situation it qccupied within the egg nucleus. The chromatin material, 

 which was aggregated into a compact and condensed structure up to 

 this time, now begins to return into a loose anastomosed com])lex of 

 numerous chromatin clumps and branched fine strands, similar to 

 those which were observed during the metamorphosis of the nucleus 

 to organize the sperm. Small new nucleoli make their appearance 

 near or in the disintegrated region (figs. 53a, h). ^\'hetht^ these 

 nucleoli result from the disintegrated blepharoplast or nuclear region 

 of the sperm or from some different source was not determined. If 

 the blepharoplast originated indirectly in the interior of the nucleus 

 from nucleoli which might have escaped during the reconstruction 

 of the nucleus of the spermatid mother cell in the last telophase 

 ifig. 11), and by a temporar}' change of staining capacity may have 

 escaped observation until they first become differentiated by stains 

 as two bodies, It might be expected that it should now reappear or 

 return again into nucleoli as it disintegrates. Thus close relation- 

 ship between the blepharoplast and nucleolus might be established. 

 However, this is entirely a speculative view, which lacks e\-idence 

 sufficient to make the suggestion probable. 



Disintegration of the body of the sperm proceeds still farther, the 

 anastomosing chromatin material showing presently the ragged reticu- 

 lar structure characteristic of the resting condition (^^5. 5-;a, b), and 

 finally the chromatin material of the sperm nucleus becomes entirely 

 anastomosed with that of the egg nucleus whose membrane now sur- 

 rounds the chromatin of both egg and sperm (fig. 33). 



The fusion nucleus in the resting condition contains two or more 

 nucleoli, some of which have appeared at the time of disintegration 

 of the sperm nucleus, w^hile others have probably resulted from the 

 union of nucleoli which already existed in the egg nucleus (fig. 33)- 

 Figures of the first segmentation dinsion are obtained in material 

 fixed a week after the entrance of the sperm had been obsen-cd. The 

 spirem which is organized at the expense of the chromatin reticulum 

 of the fusion nucleus has a continuous structure, without any indica- 

 tion of two chromatin constituents of maternal and paternal ongin. 

 WTiether there exists one or two sph-ems was not determined, but even 

 if there be present more than one spirem they are exactly similar in 



