342 THOS. H. MONTGOMERY, 



that the giant spermatogonia are spermatogonia which commence with 

 hypertrophy and end with atrophy. Though I have not been able to 

 find all stages in this line of degeneration, yet we may reasonably 

 conclude that these cells do not represent a special generation of 

 spermatogonia, but that they stand out of the regular line of the 

 sperraatogenetic cycle. For this reason I have relegated their de- 

 scription to this part of the paper. . 



VIII. The Number of Chromosomes in Cells not of the 

 Spermatogenetic Series. 



Here will be mentioned briefly some observations on the number 

 of chromosomes in tissue cells of Peripatus, which tend to show that 

 the number of chromosomes in the spermatogonia, namely 28, is ap- 

 parently the same as in the tissue cells, and accordingly that this 

 number may be called the normal one. The only tissues which I had 

 the opportunity to examine, besides those of the male genitalia whose 

 cells do not fall into the spermatogenetic category, were the sheath 

 cells of the testis, the blood cells (some of which adhered to the sur- 

 face of the genitalia), and certain cells of the ovogenetic series and 

 cells of an embryo. 



1. Yolk Cells of the Testis Sheath. 



Fig. 238, Plate 23, shows a cell in the prophase of mitosis, ap- 

 parently a segmented spirem stage. Some 19 chromosomes can be 

 counted. I could not be sure, however, that all the chromosomes 

 were contained in this section. 



3. Blood (haemolyinph) cells. 



Fig. 234, Plate 23, shows in contact with the outer surface of a 

 testis a portion of a pseudoepithelium consisting of two cells, without 

 definite cell boundaries. One of the nuclei is very small and in the 

 rest condition. The other is in mitosis, and is evidently the pole view 

 of a monaster stage; it shows approximately 26 chromosomes. 



3. Cells of the Ovogenetic Series. 



Fig. 228, Plate 23, shows a pole view of a monaster stage of an 

 ovogonium, containing 28 chromosomes. 



Figs. 230, 231 show two sections, which contain all the chromo- 

 somes, of a mitosis of one of those cells of the ovary which form 

 the stalks by which the ova are attached to the surface of the ovary. 



