EARLY DEVELOPMENT OF HYDRA. 29 



change in the nucleus which later becomes scattered and absorbed 

 in the cytoplasm, {b) By a union with neighboring cells which 

 later, either in whole or in part, become transformed into the 

 so-called pseudo-cells. This process may consist in the engulf- 

 ment of whole cells. 



3. The pseudo-cells are metamorphosed whole cells, nuclei or 

 nucleoli, in which certain characteristic changes have been brought 

 about. These changes are doubtless produced by a chemic in- 

 fluence from the egg. 



This paper was undertaken at the suggestion of Dr. C. W. 

 Hargitt. I desire to express my sense of obligation to him for 

 his valuable criticisms and helpful suggestions. 



LITERATURE. 

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