282 NATHAN FASTEN. 



of them could be counted. But on the assumption that there 

 are twice the number of spermatogonial chromosomes as are 

 found in the reduction division, there must be one hundred and 

 twenty chromosomes in the spermatogonial stages of Cancer 

 magister. 



The anaphase (Fig. 5), and telephase (Figs. 6 and 7) stages 

 follow each other quickly, thus dividing the cell into secondary 

 spermatogonia (Fig. 8). These are somewhat smaller than the 

 primary spermatogonia (compare Figs. I and 8 ), and in the resting 

 condition (Fig. 8), the chromatin of their nuclei stains much more 

 heavily. Otherwise, the secondary spermatogonia resemble the 

 primary ones markedly and their division proceeds in exactly 

 the same fashion. The ultimate divisions of the secondary 

 spermatogonia produce the resting primary spermatocytes 

 (Fig. 16). 



In many spermatogonial strips of the tubules, some of the cells 

 were found to be undergoing degeneration. In such cases, the 

 cells lose .their distinctness of outline and their nuclei come to lie 

 in a syncitial mass of protoplasm. In many instances, the nuclei 

 resemble those of the spermatogonia (compare Fig. 9 with Fig. 

 i); in others (Figs. 10-12), the nuclei become transformed into 

 very large irregular structures with pseudopodia-like projections. 

 These cells are the so-called "nutritive cells" and they may be 

 best studied in tubules where mature spermatozoa are found. 

 In Cambarus virilis, I ('14) have noticed similar cells. 



The nutritive cells (Figs. 9-15) are very interesting structures. 

 Their nuclei contain heavily staining chromatin masses, while 

 the cytoplasm possesses numerous fat globules which stain 

 intensely black with osmic acid. Many of the earlier investi- 

 gators on the Decapoda such as Grobben ('78), Gilson ('86), 

 and Herrmann ('90) have claimed that the spermatogonia are 

 derived from the nutritive cells. On the other hand, St. George 

 ('92), and Keppen ('06) claim the opposite, that the nutritive 

 cells are derived from a transformation of the spermatogonia. 

 This last-mentioned condition seems to be the case in Cancer 

 magister. 



When sections of the nutritive cells are examined, numerous 

 stages like those seen in Figs. 13-15 may be observed, w r hich 



