SPERMATOGENESIS OF CANCER MAGISTER. 283 



strongly suggest amitosis. The fact is that the earlier workers 

 on the Decapoda all claim such division in the nutritive cells. 

 However, a careful study of the nuclei shows many of them to be 

 ambceoid in appearance (Figs. 10-12), and this being the case, 

 it is entirely possible to derive the stages represented in Figs. 

 1315 from sections through such cells as are shown in Figs. 10-12. 

 It is, therefore, very difficult as well as dangerous to come to any 

 certain conclusions concerning amitosis from sectioned material. 



B. Primary Spermatocyte Stage. 



This stage follows the spermatogonial divisions. After a 

 period of growth and synapsis, reduction occurs. During the 

 growth period two definite spherical bodies, surrounded by clear 

 spaces, make their appearance in the cytoplasm. These are 

 the so-called chromatoid bodies, and they appear to be similar 

 to the same structures which I ('14) have previously described 

 in Cambarus virilis. 



(a) Growth Period. This period includes the preparatory 

 stages, synapsis and tetrad formation. During the early pro- 

 phases the chromatin in the nucleus of the resting primary sper- 

 matocyte (Fig. 16), consists first of a few large, heavily staining 

 clumps, but these soon undergo a fragmentation process, whereby 

 smaller chromatin masses (Fig. 17) are produced. In a few cells, 

 linin threads which were rather indistinct and granular in appear- 

 ance were observed. Sometimes large chromatoidal masses like 

 those shown in Fig. 17 were seen within the cytoplasm. 



The chromatin of the nucleus breaks up into still smaller 

 structures and these then begin to weave out into thin leptotene 

 threads (Fig. 18). At the same time the cell increases somewhat 

 in size (compare Figs. 16 and 17 with Fig. 18). This stage, 

 represented by Fig. 18, really marks the beginning of the growth 

 period and from now on the increase in the size of the cells is more 

 evident. When Fig. 18 is examined it can be seen that no con- 

 tinuous spireme is formed. The leptotene threads remain separ- 

 ate and may be distinguished from each other. Owing to the 

 great number of these threads it was impossible to count them. 



The primary spermatocytes now undergo synizesis. The 

 leptotene threads migrate to one pole of the nucleus (Fig. 19), 



