SUTTON : SPERMATOGONIAL DIVISIONS IN BRACHYSTOLA MAGNA. 147 



presence as a matter of course, and merely alluding to them in de- 

 scription of other elements of the testis. 



St. George, in 1876, described these structures in liana tewpomrui 

 He found the cyst membranes of each group of spermatogonia to lie 

 ^vithm, though generally not mechanically continuous with other 

 membranous compartments which were to be distinguished from the 

 cyst membrane only by careful observation. These latter are con 

 tmuous with the walls of the canal and with one another, and serve 

 to support the cysts. Each membrane has its nuclei which are 

 easily distinguished from each other by the arrangement of their 

 chromatin. As to the origin of the cysts, his opinion is that a single 

 early cell is surrounded by other cells, which latter become continu- 

 ous with one another, and, losing their protoplasm to a large degree 

 gradually assume the form of a membrane, while the single cell thus 

 imprisoned gives rise by constriction of its nucleus to the cells of the 

 mature cyst. 



Henking, in 1891 {l\jrrho<-orh), first mentions the cyst membrane 

 111 describing groups of cells of considerable size. In older mem 

 branes, he saw large nuclei resembling those of connective tissue cells 

 each having about it a layer of cytoplasm. He noted that all the 

 cells of a given cyst are in approximately the same stage of division 

 and that the equatorial plates of the division figures were uniformly 

 tangential to the circumference of the cyst as seen in section He 

 also mentions groups of cells lying in circles about differently con 

 structed central cells, which latter are easily distinguished by their 

 large size and poverty of chromatin. This condition probably cor 

 responds to that shown in fig. G, and, if so, argues an origin of cysts 

 similar to that in Bracliystola. 



Vom Rath, in 1892 ( Gryllotal^a), says nothing of the presence of 

 cysts mhis object, but the conical shape of certain spermatogonia 

 hgured m his plates is a strong indication of their presence 



Toyama, 1891 {Bou.hyx), si^e^ks of the arrangement of the earlv 

 conical cells with their apices attached to the processes of supportin.- 

 cells. He describes the sperm- . cells as grouped in cysts, and 



notes the synchronous division of the cells of each group 



Montgomery, in 1898 (Pentatoma), goes into the subject more in 

 detail. After describing the six follicles of which each testis is com- 

 posed, he says: "Each follicle is bounded by a sheath of connective 

 tissue formed of interlacing, branched, connective tissue cells, some of 

 which also penetrate the interior of the follicles. These branching 

 processes of these connective tissue cells serve to demarcate more or 

 less spherical groups of cells, the spermatocysts of v. la Vallette St 

 G-eorge." He has not seen the formatian of the cysts, but thinks it 



ll-K.U.Qr. A-ix2 



