2O6 C. M. CHILD. 



bildet haben mit den Samenfaden fortgespielt." Sommer's prep- 

 arations were obtained by maceration and teasing and without 

 staining. As described, the fate of the nuclei does not differ 

 very widely from that described in the present paper except for 

 the fact that Sommer failed to observe that any portion of the 

 nucleus took part in the formation of the spermatozoon. Con- 

 sidering the methods employed this failure is not strange. 



Moniez l describes the formation of large multinucleate cells 

 and the protrusion from their surface of the nuclei which are united 

 with the body of the cell by pedicels (these are evidently the 

 spermatids on the cytophore). He continues as follows : " Ces 

 nouvelles formations qui rayonnent de la cellule-mere sont les vrais 

 spermatozoides : leur flagellum se forme a la partie peripherique, 

 tandis qu'ils sont encore fixe par 1'autre extremite ; c'est apres 

 qu'ils se sont detaches que leur tete s'atrophie comme Ton sait." 

 These facts he describes as common to a number of species 

 among them Tcenia expansa, i. e., Moniezia expansa as it is now 

 known. 



In describing the spermatozoa of Tcenia saginata Leuckart 2 

 speaks of the " freilich kaum ausgezeichneten " head. 



From all of these observations it is evident that where a dis- 

 tinct head is visible it is exceedingly minute and the observations 

 of Salensky, Sommer, and Moniez seem to indicate that the sper- 

 matozoa of several species are without visible heads. The 

 description of the collapse and degeneration of the nuclei bySom- 

 merand the mention of atrophy of the head by Moniez appear to 

 be somewhat closely in line with my own observations. But until 

 other species have been examined with the aid of present cytolog- 

 ical methods general conclusions are impossible. I am convinced, 

 however, that if the spermatozoa of Moniezia possessed distinct, 

 visibly differentiated heads I should have seen them in some cases 

 at least. Comparative study of other species will undoubtedly 

 prove of interest. 



VII. The Degeneration of Cell-Groups in the Testis. 



During almost the whole period of existence of the testis groups 

 of cells undergo degeneration from time to time. Cells in any 



1 Moniez, " Sur les Spermatozoides des Cestodes," Comptes Rendus, 1878. 



2 Leuckart, " Die Parasiten des Menschen," 1879-1886. 



