.StiKlies in Crustacean Spermatogenesis. 475 



one side of the vas become greatly enlarged, and the nuclei amoeboid. 

 The nucleus at first contains granules, a few sharply staining, the 

 numerous remainder less densely colored. It expands and fragments 

 and the contents become finely gi^anular, except for a few which 

 remain somewhat larger and darker. (PI. 3. I, 2(i-2T.) Gran- 

 ules, however, do not ai)pear in the cytoplasm, which becomes more 

 and more vacuolated and finally commences to disintegrate. The 

 appearance of these secretory cells is quite different from that of the 

 land Isopoda. (PI. 3. O, 6.) There they are far larger, the 

 nuclear granules more nearly uniform in size, and the cytoplasm 

 filled with similar granules which stain less intensely than those 

 within the nucleus. (Nichols, 1902.) 



The structure of the testis of Talorchestia is somew^hat simpler 

 than that of the Isopoda. It consists of a single follicle in which the 

 germ cells develop in laterally arranged areas. There is no con- 

 striction between the testis and the upper portion of the vas and in 

 longitudinal section germ cells are found on one side of the lumen, 

 secreting cells on the other. (PI. 3. T, 23.) The secreting cells 

 are different in appearance from those of the Isopoda. Some of the 

 cells contain nuclei comparatively small with the chromatin showing 

 a decided tendency to gather in lumps close to the nuclear wall. 

 (PL 3. T, 19.) The nucleus increases in size and sometimes be- 

 comes amoeboid at its margin (PI. 3. T, 20) and the chromosome 

 granules become more distributed through the nucleoplasm. Other 

 cells contain nuclei of greater size in which the chromatin is no 

 longer applied to the nuclear wall, but consists of irregular masses 

 connected with each other and with the well-defined nuclear mem- 

 brane by a delicate network. (PI. 3. T, 21.) In one cell a large 

 vacuole was seen in the center. (PI. 3. T, 22.) This condition 

 is probably degenerative, since the cells adjacent to th-e germ cells 

 disintegrate. (PI. 3. T, 23.) 



The testis of the Decopoda is more complicated in structure than 

 that of the Amphipoda and Isopoda. It consists of numerous closely 

 crowded follicles opening into a much coiled tube. Dift'erent follicles 

 of Hippa contain during the breeding season different stages in the 

 development of the germ cells and a continuous series is therefore 



