386 HARRY H. CHARLTON 



the nuclear wall (figs. 11 and 16). At a little later stage one 

 commonly finds an irregular clump of chromatic material repre- 

 senting apparently two spermatogonial chromosomes lying 

 against the nuclear membrane and retaining the haematoxylin 

 stain (figs. 13, 14, and 15). For these chromosomes I shall use 

 the term idiochromosomes, the name given by Wilson ('05) 

 and meaning 'peculiar or distinctive chromosomes. 7 



In some presumably young cysts the spermatogonial cells 

 are arranged in the form of a rosette, their median ends tapering 

 toward a faintly marked open center and showing an archo- 

 plasmic mass or sphere (figs. 4 and 18). Hegner ('14), Meves 

 ('97), and Shaffer ('17), as well as others, have described similar 

 structures and considered them spindle remains. In some cases 

 they figure them as extending from cell to cell. While this is 

 true immediately after division when the spindle remains are 

 very definite (fig. 7), it is not possible later to see any continu- 

 ation or connection with similar bodies in adjacent cells. 



In the spermatogonial region isolated cells are occasionally 

 seen in division, but, strangely enough, the chromosomes are 

 paired and look somewhat like tetrads (fig. 32). The cells 

 themselves are much larger than the spermatogonia and contain 

 but little cytoplasmic staining material in the form of a flaky 

 mass at either end of the cell in which a dark-staining granule 

 may be seen. If these represent division in the Sertoli cells, 

 they are a very rare occurrence. In the older Sertoli cells I 

 have occasionally seen evidence indicating division by amitosis. 



The growth period 



The stages of the growth period correspond fairly closely with 

 the stages described by Wilson ('12). After the telophase, 

 chromosomes of the last spermatogonial division break up and 

 form a granular ring just inside the nuclear wall, the chromatin 

 arranges itself as previously described in the form of clumps 

 located on the nuclear membrane (Wilson's stage b, similar to 

 fig. 13). In heavily destained material two of these are closely 

 related, one of them being flattened against the nuclear mem- 



