SPERMATOGENESIS OF CANCER MAGISTER. 28l 



ous large chromatin clumps within the nucleus. In some in- 

 stances a number of linin strands could also be distinguished. 

 The cytoplasm is more or less uniform throughout, but in a few 

 cases large heavily staining masses, surrounded by clear outlines 

 (Fig. 2), could be observed within it. A centrosome is almost 

 always discernible. 



When the cell begins to divide the large chromatin clumps of 

 the nucleus undergo fragmentation (Fig. 2). This process con- 

 tinues until the chromatin becomes organized into a great number 

 of heavily staining elliptical or oval structures distributed 

 throughout the nucleus. The spermatogonium at this stage 

 presents the picture shown in Fig. 3. Counts of these chromatin 

 clumps were attempted, but they were found to vary consider- 

 ably, ranging everywhere from forty to sixty-five. Binford 

 ('13) has made similar observations in Menippe mercenaria and 

 in the American crayfish Cambarus virilis, I ('14) have found 

 the same sequence of events. Binford regards these chromatin 

 clumps as the chromosomes which enter the equatorial plate of 

 the spermatogonial metaphase. While these through a further 

 fragmentation, undoubtedly form the ultimate number of chro- 

 mosomes found during the metaphase stage of the spermato- 

 gonial division, yet I am inclined to the view that many of these 

 chromatin clumps represent more than single chromosomes. 

 This conclusion was arrived at after examination of numerous 

 polar views of the chromosomes in metaphase plates of primary 

 spermatogonia, in which over one hundred chromosomes could 

 be counted. Furthermore, these chromosomes were smaller than 

 the chromatin clumps shown in Fig. 3. 



The nuclear wall surrounding the chromatin clumps soon 

 breaks down and the cell enters the metaphase stage (Fig. 4). 

 The chromosomes in the equatorial plate are dumb-bell shaped 

 and the spindle fibers are rather delicate in appearance. The 

 centrosomes can be easily distinguished at opposite poles. In 

 polar views of sections of the equatorial plate, the chromosomes 

 are observed to be distributed throughout the whole plane of the 

 equator. They are small and spherical in appearance, and are 

 so numerous that their exact number could not be determined. 

 As already mentioned above, in many instances over one hundred 



