SPERMATOGENESIS OF CANCER MAGISTER. 287 



"Such facts make it clear that the presence of sex-chromosomes 

 can not safely be inferred alone from the presence of chromosome- 

 like bodies lagging on the spermatocyte-spindles, or lying near 

 one pole. The presence of compact, deeply staining nucleoli 

 during the growth-period is by itself equally indecisive. In some 

 cases the 'plasmosome,' especially after certain fixatives such as 

 Bouin's fluid, may stain quite as intensely as the chromosome- 

 nucleoli with haematoxylin, safranin and other dyes (cf. Gutherz, 

 '12). Decisive evidence regarding these bodies can only be 

 obtained by tracing their individual history and by accurate 

 correlation of the chromosome-numbers in the spermatogonial 

 and spermatocyte-divisions. It hardly need be added that great 

 caution is necessary in dealing with difficult material in which 

 for any reason such a test cannot be completely carried out." 



The anaphase stage (Fig. 29) follows upon the metaphase. 

 The bivalents of the dumb-bells are separated and pulled to 

 opposite poles. The chromatoid bodies also migrate in these 

 directions. The division process continues and gradually the 

 primary spermatocyte enters the telophase stage (Figs. 30 and 

 31). In the final telophase (Fig. 32), the chromosomes which 

 have completely migrated to opposite poles become surrounded 

 by thin nuclear walls. The cytoplasm has constricted off into 

 two distinct portions and during this process the spindle fibers 

 have also been constricted so that at their center a thickened 

 " zwischenkorper " is formed. When this stage is completed two 

 secondary spermatocytes are produced, each possessing one of 

 the chromatoid bodies within the cytoplasm (Fig. 32). 



C. Secondary Spermatocyte Stage. 



The secondary spermatocytes formed during the ultimate 

 telophase stage of the reduction division, undergo immediate 

 transformations. No rest period could be determined. This is 

 similar to what occurs in Astacus fluviatilis (Prowazek, '02), in 

 Menippe mercenaria (Binford, '13), and in Cambarus virilis 

 (Fasten, '14). The cells assume the metaphase stage (Fig. 33), 

 and the chromosomes line up in the equator of the spindles in the 

 form of dumb-bells. When polar views of these chromosomes 

 are studied in preparations which have been greatly destained, 



