262 FRANZ SCHRADER. 



triangle, while the sister group which goes to the opposite pole is 

 circular or lumped in arrangement (Figs. 21 and 22). This 

 grouping is so constant and has been observed in so many speci- 

 mens, that no mistake seems possible, and the conclusion seems 

 inescapable that it is of some significance. The telophase of this 

 anomalous division still shows traces of the arrangement, but 

 these are soon lost as the chromosomes of each daughter cell dis- 

 tribute themselves around the periphery of the nucleus. Their 

 number here is undoubtedly five (Fig. 24). This initiates the 

 formation of the spermatids in which the chromosomes gradually 

 loose their staining reaction. No study of the subsequent stages 

 was made except to determine that there is no sign of degenerat- 

 ing or abortive cells nor a size dimorphism in the spermatozoa. 



SOMATIC CHROMOSOMES. 



Returning to the somatic tissues, it may be remarked here that 

 although the number of chromosomes in each sex is the same, 

 their arrangement differs in the two sexes. This is especially 

 noticeable in the developing nerve tract, where in the male the 

 cells in the resting stage show a relatively large nucleolus like 

 structure (Fig. 2). This is not to be seen in the same tissue in the 

 female where cells show only the flocculent chromatin peculiar to 

 that phase (Fig. i). That the nucleolus-like structure in the 

 male nerve cells is nothing but the group of five chromosomes 

 mentioned in the description of the spermatogenesis becomes 

 almost certain in metaphase plates found in the same tissue. 

 Figs. 3 and 4 show such grouping without a doubt. 



Exactly the same feature is observable in spermatogonial plates, 

 though the size of these renders them less favorable (Fig. 5). In 

 contradistinction, oogonial plates have no such arrangement, and 

 even in such a late stage before division as shown in Fig. 6 the 

 chromosomes are arranged in no definite order. 



DISCUSSION. 



An interpretation of these observations is perhaps not out of 

 place. It is here given with the idea that it should not affect the 

 observations however it may be received and is advanced in a 

 speculative way. 



