muoh dependence in these numbers for soiirie of the spheres are 

 always somewhat aggregated In one or two places so that they 

 oan not be definitely distinguished. These chromosomes at 

 first lie in the outer part of the nucleus just inside the 

 nuclear membrane, but are later massed in the center, from 

 which condition they move to their positions in the equitorial 

 plate. Figure 7 is an optical section of the nucleus showing 

 the peripheral arrangement of the chromosomes, m the meta- 

 phase and anaphase of the mitosis the members of each pair 

 are separated from each other and pass to opposite poles of 

 the spindle iPig. 8>. These divisions of the spermatogonial 

 nuclei do not occur simultaneously throughout the mass, but 

 singly here and there amongst the nuclei. The spermatogonia 

 become smaller as they become more numerous. 



6. Maturation Mitoses . 



Finally the spermatogonial divisions cease and the nuclei 

 prepare for the reduction divisions. The quantity of chromatin 

 seems to increase and the spireme makes its appearance. At 

 first it is very long and slender and complexly folded all 

 through the nucleus. The iron-haematoxylin stain can be con- 

 trolled so that the spireme has the appearance of a brown 

 thread with granules distributed irregularly along it iFlg.9). 

 The diameter of the granules is slightly greater than that of 

 the thread between the granules. The spireme now becomes 

 shorter and thicker and is finally massed at one side of the 

 nucleus in the condition of synapsis (Fig. 10). This stage 

 persists for a comparatively long period. The spermatocytes 



