266 T. IWAKAWA. 



assumed to belong also to all young egg-cells. Whatever 

 evidences may be produced in the future in favour of this 

 view, it must for the present be regarded, I think, as a theory 

 without any proper basis. 



Automatic action is a character belonging to the proto- 

 plasm of young cells in general ; and I fail to see any 

 evidence for the assumption that young epithelial cells 

 "execute movements under no conditions." 



Epithelial Islatids. 



The epithelial islands discovered by Waldeyer have been 

 mentioned by other authors, and interpreted in various 

 ways. 



Spengel (10), describing the ovary of the Urodela, says, 

 " Its outer surface is covered with peritoneal epithelium, 

 which in the adult animal preserves, in places, the character 

 of germinal epithelium, and serves to replace the eggs that 

 have matured." 



Brandt (11) succeeded in finding in the frog only a single 

 case comparable with the cell islands of Waldeyer. 



Kolessnikow (12) has described " Keim-epithelinseln'^ 

 found in Triton, Salamander, and Frog. Speaking of the 

 frog, he says : — " Groups of peculiar cells are to be seen 

 from place to . place between the endothelial cells ; these 

 cells show a granular protoplasm, and larger or smaller 

 nuclei ; they have sometimes a round, sometimes a poly- 

 gonal form, and among them lie single cells, distinguished 

 from them in size, size of nucleus, and richness in proto- 

 plasm. The contours of these peculiar cells and the bound- 

 ing lines separating them from the neighbouring endothelial 



cells are always plain to be seen I regard the 



groups of cells just mentioned as islands of germinal epi- 

 thelium, in which the enlarged cells appear as primordial 

 eggs. The size of the islands is -093 to '186 mm., that of 

 the cells -0139 to -0232 mm. 



" In places these epithelial cells are seen to lie under the 

 endothelium, i.e. covered by it. In such places they form 

 sometimes deep and broad, sometimes small groups, which 

 often stand in connection with the superficial germinal 

 epithelium.^' 



In regard to the origin of these islands, Kolessnikow 

 expresses himself thus : 



''With the transformation of the sexual gland into an 

 ovary begins a more rapid growth of the stroma on the one 

 hand, and a relatively slower growth of germinal epithelium 

 on the other, and the result (of this unequal growth) is that 



