No. I.] SPERMATOGENESIS OF BATRACHOSEPS. 53 



nuclei occur only in the earliest resting stages, but as there 

 are no other cells possessing similar nuclei, no difficulty will 

 be encountered in recognizing the cells. In testes from ani- 

 mals killed in June and July there are comparatively few poly- 

 morphous nuclei, frequently only one or two, seldom more than 

 three or four, in each section of a pocket of cells. The other 

 cells in the pocket are mostly spermatogonia with round nuclei, 



A polymorphous spermatogonium in the " perfect resting stage." The form of the nucleus allows 

 the most perfect metabolism. Numerous chromioles are connected by a thread of chromo- 

 plasm. A network of linosomes is partially indicated, the individual granules being con- 

 nected by linopodia. A large, oblong chromoplast with endochromatic granules. Eight 

 parachromatic granules. A single archosome in the cytoplasm, the latter only partially 

 indicated by small open circles. A single large, round linoplast, with seven endonucleolar 

 granules. 



the direct descendants of the polymorphous nuclei belonging 

 to the imperfect resting stage and immediately preceding the 

 prophases of mitosis. 



The polymorphous nuclei are not only characterized by their 

 form, but also by the appearance of the nuclear contents. At 

 first sight it appears as if the nucleus had not been properly 

 fixed, but as if the chromatin had been disarranged and not 

 taken the stain in a proper way. But a more careful study of 



