NOTES ON THE REPRODUCTION OF HYDRA IN THE 

 CHAPEL HILL REGION 



By H. S. Everett 



In the course of an investigation dealing with the germ cells of 

 TTydra during 1920-1921, a nnmher of observations were made on the 

 occurrence and habits of hydras in the region around Chapel Hill. 

 The work continued over a period from October until June, and it 

 is the purpose of this article to record briefly such data as may be 

 of general use and interest to the worker on Hydra in the Chapel 

 Hill region. 



Two species, H. viridis and H. grisea, were found throughout the 

 period in collections of leaves, trash, and green algae from pools 

 and swamps near the town. In the spring they occurred in much 

 greater abundance out of doors than in the fall and winter. 



H. grisea was always found budding vigorously, but showed no 

 sex organs until late in ^May, when some specimens which had re- 

 mained in aquaria in the laboratory for about two weeks developed 

 gonads. Although green hydras were not found in a sexual state 

 out of doors until April, animals could be found in the laboratory 

 with gonads at nearly all seasons. This species (H. viridis) appeared 

 in three aquaria, the material of which was collected early in October. 

 The hydras underwent a period of vigorous budding, after which 

 about the first of December large numbers developed sex organs. 

 This sexual period lasted about a month. After it had ceased the 

 animals in two of the aquaria seemed to be well-nourished and con- 

 tinued to bud for some months, but never returned to the sexual 

 state. Those in the third aquaria seemed to be underfed, budding 

 practically ceased, and they began to grow smaller. A careful exami- 

 nation of them about February the first revealed the fact that eighty- 

 two per cent of them possessed male sex organs. This observation 

 was in complete agreement with the statement often made that the 

 spermaries are produced as a result of starvation. But though this 

 may be one stimulus for the production of the sperm, it is certainly 

 not the only one, at least in //. viridis, for the ovaries are never 



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