298 * J. E. WODSEDALEK. 



and 2). Other nucleoli varying considerably in size, shape, and 

 number also appear in some of the cells (Fig. 2). 



Before the chromosomes begin to form the cells increase greatly 

 in size (Fig. 2). At the conclusion of the resting stage numerous 

 large chromatin granules appear which arrange themselves along 

 fine threads in an entangled mass. The chromosomes soon 

 become distinct and while, as a rule, a count is impossible on 

 account of the overlapping and massing together of the chromo- 

 somes, [the mitotic stages were abundant and many distinct 

 counts could be made. Thirty-seven chromosomes appear in 

 the late prophases of the spermatogonial division (Figs. 4 and 5). 

 Thirty-six of these are variously shaped, mainly oblong, and 

 differ somewhat in size. One which is much larger is, as a rule, 

 somewhat triangular or heart-shaped. This is the accessory 

 chromosome and is the same thing as the large nucleolus which 

 appears in the resting stages. That is certain, as the body can 

 easily be traced through the various stages of growth. This 

 condition is similar to that found by Guyer ('10) in man, and 

 Wodsedalek ('13) in the pig. Ordinarily about two thirds of the 

 chromosomes arrange themselves in a ring which encircles the 

 remaining one third. The accessory chromosome may be found 

 anywhere within the mass, and occasionally occurs outside of the 

 main ring, but never far removed from the other chromosomes. 

 During division each chromosome divides in two. The accessory 

 as a rule divides a little in advance of the other chromosomes 

 (Figs. 6 and 7). 



The spermatogonia in this, as well as other stages, vary some- 

 what in size (Figs. 6 and 7). In the smaller cells the cytoplasm 

 appears denser and the chromosomes are more crowded together. 



V. PRIMARY SPERMATOCYTES. 

 i. Resting Stage. 



The primary spermatocytes arising from the final spermato- 

 gonial division in the early resting stage are usually smaller 

 than the spermatogonia immediately preceding and during the 

 division stages. After the disintegration of the chromosomes 

 the nucleus appears much clearer than it does in the later growing 

 stages. The large nucleolus is again very conspicuous and easy 



