12 RALPH E. WAGER. 



morphosis. He observed that several of these persistent nuclei 

 are often swept into the same vacuole by streaming movements 

 of the protoplasm. He describes cases of the amitotic division 

 of these nuclei as being of frequent occurrence within the egg. 



Allen ('oo) describes the changes undergone by the engulfed 

 nuclei in the growing egg of Ttibularia crocea. Many nuclei were 

 found within the cytoplasm of the egg which showed no differ- 

 ence from the nuclei of the cells of the germinal layer. 



These changes consisted in the assembling of the chromatin 

 filaments into a varying number of small spheres just within the 

 nuclear membrane, the disappearance of the threads supporting 

 the nucleolus and a chemic change in the character of the ground 

 substance supporting the chromatin, such that it becomes reactive 

 to staining agents. The structure of the nucleus becomes less 

 distinct. A description is also given of amitotic divisions of these 

 nuclei within the cytoplasm of the egg. Her results agree largely 

 with those of Doflein ('97). 



Tannreuther ('08) observes that some of the nuclei of the in- 

 terstitial cells surrounding the egg are taken up by it and trans- 

 formed into pseudo-cells. The transformation is accomplished 

 by the granulation of the chromatin ; its arrangment in a band 

 around the inner border of the nucleus, and the imbedding of the 

 nucleoli within this band thus presenting the "appearance of a 

 hollow sphere with its wall thicked on one side." 



Downing ('08) believes them to consist of lecithin which at 

 first is diffuse in the egg but later becomes aggregated to form the 

 pseudo-cells. He notes also that the nuclei of the interstitial 

 cells become filled with it, meantime enlarging considerably. 

 These nuclei, he says, may also eventually give rise to the pseudo- 

 cells. 



It is evident from the above that two views have prevailed as 

 to the origin of the pseudo-cell. The one, that held by the 

 earlier writers principally, that they were accumulations or 

 growths within the cytoplasm of the egg ; the other, that they 

 are the persistent and metamorphosed nuclei of the cells which 

 fuse or coalesce with the egg in the process of its growth. 



My studies have convinced me that they may be due to both 

 of these processes, but that in the Hydra at least, these darkly 



