148 KANSAS UNIVERSITY QUARTERLY. 



probable that in the embryonic testis there is a network of connective 

 tissue, in each mesh of which is contained "a single spermatogonium, 

 or at least only a small number of spermatogonia." The cysts are 

 then built up by the division of these cells, the cyst membrane being 

 formed by the extension of the connective tissue investment. The 

 maturer cysts are forced towards the rcrs deferens by the growth of 

 the younger ones beyond. This supposed origin of the cyst in I^e/i- 

 tatoma differs from the process as seen in Bfachysfola mainly in the 

 implied difference in origin in Montgomery's description between the 

 sperm-cells and those of the cyst walls. 



Paulmier, 1899, states distinctly that in his material {Anasa) the 

 spermatogonia occur at the blind end of the follicle singly or in groups 

 not yet surrounded by a membrane. After a certain number of divi- 

 sions, each group becomes surrounded by a connective tissue wall 

 continuous with the lining of the follicle, and the cells assume the 

 conical shape noted by Henkiag, Montgomery, and others, and figured 

 by vom Rath. 



McGregor, 1899 {Amphltinia), gives the presence of the cyst mem- 

 brane about groups of secondary spermatogonia as one of the chief 

 points of distinction between them and their predecessors, the pri- 

 mary spermatogonia. He notes the conical form of the cells of the 

 younger groups and the fact that the secondary spermatogonia arise 

 from the primary, but has nothing to say in regard to the number of 

 primary spermatogonia taking part in the formation of a single cyst. 



My own observations correspond, with more or less exactness, to 

 something in each of these descriptions, though in many cases they 

 present radical differences. 



First, I find primary spermatogonia and secondary spermatogonia 

 as McGregor does, but in Braehystola the primary .spermatogonia do 

 not divide amitotically, as he reports them for Amphhnnd. 



Second, the primary spermatogonia change to secondary sperma- 

 togonia, but a cyst is formed and a cyst membrane appears even in 

 the two-cell stage ; the latter being sometimes indicated in metaphase 

 of the transformation division. (Fig. D, a.) 



Third, the cyst membranes have nuclei, as reported by many, but 

 they are identical with those of the resting primary spermatogonia. 



Fourth, the cells in the young cyst assume a roughly pyramidal 

 shape, as described by most authors, and tend to divide tangentially to 

 the periphery of the cyst, as described by Henking : also, except in 

 special cases, all the cells of a cyst divide almost simultaneously. 



Fifth, occasionally a different sort of cell is seen in the middle of 

 a young cyst of secondary spermatogonia, as described by Henking. 



Sixth, the number of divisions of the secondary spermatogonia 



