262 



THE BIOLOGY OF HYDRA : 1961 



^ 80 



10 



FED EVERY THIRD DAY 



GREEN ^ 



ALBINO t 



J I \ \ \ L 



TIME IN DAYS 

 Fig. 6. Same as Figure 5 but fed every third day. 



survived an additional 7-10 days until gradual diminution in size 

 resulted in death. In contrast, albino C. viridissima, under these 

 conditions, stopped budding after 1-3 days; within the next six days, 

 all had disintegrated. These results show that the algae are essential 

 for prolonged survival under starvation conditions. 



Early disintegration and death of albinos was unusual since a 

 characteristic of most species of hydra, including green C. viridis- 

 sima, is to gradually "waste away" when starved ( 1 ) . One explana- 

 tion of this death gives us a clue to a possible nutritional role of the 

 algae. Dixon (2) has stated that tissue death results from inability 

 to synthesize coenzymes. By removing algae from C. viridissima we 

 may have removed a source of coenzymes, or coenzyme precursors, 

 normally available from algae during starvation or from food during 

 normal feeding conditions. This idea fits well with results of limited 

 food experiments, where green hydra show maximum growth imme- 



