REMOVAL OF GREEN BODIES OF HYDRA VIRID1S. 2Q7 



small dish, which was suspended in another large aquarium about 

 three inches from the lighted side, made their way to the lighted 

 side and there became attached. Those that remained in the 

 small dish collected upon its lighted side. 



Some of the early workers suggested that Hydra viridis might 

 be a variety of Hydra fusca which had acquired the power of 

 harboring green algae in its cells. Greenwood and others found 

 that the endoderm cells of green hydras contain brownish colored 

 bodies similar to or identical with the same colored bodies in the 

 cells of Hydra fusca. This brownish color is masked in Hydra 

 viridis by the green color of the algae. 



Interesting as this suggestion is, the evidence from the colorless 

 hydras is opposed to it. The Hydra viridis that has lost its green 

 color in the glycerine solution is smaller in size, has shorter 

 tentacles, produces fewer buds at any one time than Hydra fusca. 

 It has a very faint tint of pink or brown color while Hydra fitsca 

 which has been in a glycerine solution 2-5 weeks has a reddish 

 orange color. 



Summary. 



1. When Hydra viridis is kept in a .5-1.5 per cent, solution 

 of glycerine it loses all its green color. 



2. The green alga passes out of the endoderm cells into the 

 digestive cavity from which it is expelled through the mouth to 

 the outside when the hydra contracts. 



3. The green alga does not continue to live outside in the 

 glycerine solution. 



4. The white hydras will live at least seventeen days without 

 food. 



5. The white hydras if fed can produce buds at the same rate 

 and in the same manner as green hydras and have been kept 

 alive for more than two months. 



6. The white hydras do not show a trace of green color, under 

 the lens, after seven weeks feeding upon contaminated food. 

 These hydras were kept in spring water during the first 2-3 

 weeks of feeding and then placed in a large balanced aquaria 

 which contained many hundreds of green hydras and much algae. 

 Thus showing that the white hydras were not reinfected under 

 very favorable conditions. 



