No. 3-] (M'/i/AV OF THE SPERM-BLASTOPHORE. 



53 



paratively large (Figs. S-u); they gradually decrease, and 

 finally disappear, as shown in Fig. 15. It would appear, there- 

 fore, that the blastophore is produced by the degeneration of 

 the central cells, and that it not only acts as a cushion, afford- 

 ing a means for conveying the spermatozoa, but also serves 

 as nourishment for them. 



Bloomfield's principal results, as briefly summarized by 

 Calkins, are as follows : 



" i. The early germ-cell is not entirely used in the forma- 

 tion of spermatozoa ; a central part remains passive, and serves 

 to carry the developing spermatic cells. This central part is 

 called the sperm-blastophore, and may or may not be nucleated. 



Fit,. 15. 



2. The sperm-blastophores increase by division while in the 

 testis, and disappear, probably by atrophy, after the spermato- 

 zoa leave it. 



3. The blastophore corresponds to the nucleated supporting 

 cells (Sertoli's cells) of the frog and salamander. 



4. The large nucleus of the early sperm-cell divides many 

 times to form secondary nuclei, which stand out around the 

 central mass, or blastophore, of the generating spheroid with 

 very little protoplasm clothing them. These nuclei become 

 the rod-like heads of the spermatozoa. 



5. The protoplasm collects in a small cup, or knob-like mass, 

 at the distal end of the developing cell, and from this grows 

 out the long vibratile tail of the spermatozoan. (This ' mass ' 

 must be the archoplasm of the spermatid.)" 



