154 HATAI. 



Calkins summarized his own results as follows : 

 "i. A multinucleated cell is formed in the testis ; this 

 represents a group of the earliest spermatic cells or spermato- 

 gonia. Each spermatogonium gives rise to several sperma- 

 tozoa. 



2. The nuclei arrange themselves around the periphery of 

 the multinucleate cell ; cytoplasmic cleavages then ensue be- 

 tween the nuclei, as in the centrolecithal egg. The cleavage 

 grooves deepen until the nuclei are separated from the central 

 mass of cytoplasm by mere filaments. 



3. The residual mass of cytoplasm thus formed (the blasto- 

 phore) is not nucleated, and cannot be compared with a Ser- 

 toli's cell in function, form, or mode of origin. It finally dis- 

 appears. The blastophore furnishes perhaps the chief source 

 of food supply for the parasites -- monocysts which live in 

 the seminal vesicles. A possible explanation of the function 

 of the blastophore is that of superfluous nutritive cytoplasm, 

 the vital protoplasm having gathered around the nuclei." 



Thus it will be seen that Bloomfield and Calkins hold very 

 different views regarding the blastophore. The former con- 

 siders it as having a nutritive or feeding function. It carries 

 developed spermatozoa, and is to be regarded as the homologue 

 of Sertoli's cell. The latter maintains that the blastophore is 

 merely an excess of cytoplasm and not a true cell ; therefore it 

 cannot be homologous with the Sertoli cell. 



The question as to the structure and function of the blasto- 

 phore in Lumbricus can be decided only when we learn its true 

 origin. In the present work on the two new species of Limi- 

 colae, it appears that the blastophore originates through the 

 degeneration of certain of the primordial germ-cells which lie 

 at the centers of the clusters of spermatogonia given off from 

 the testes. 



It serves not only for carrying developed spermatozoa, but 

 for their nourishment as well. Thus it arises from definite 

 cells, and, as Bloomfield has suggested, may be compared to the 

 Sertoli s cell. 



HULL ANATOMICAL LABORATORY, 

 UNIVKRSITY OF CHICAGO. 



