126 



PEEBLES. 



[Vol. II. 



recorded. Forty-six individuals were used in a series of six 

 experiments. 



Table i. — Hydra Viridis. 



The rate of regeneration in Table i may be compared with 

 the rate for Hydra viridis at room temperature, given in 

 Table 2, where the results from forty-five individuals in eight 

 experiments are given. 



Table 2. — Hydra Viridis. 



Temperature. 



I»-24" 



Per Cent Regenerated. 



48 hrs. 



37-8% 



72 hrs. 

 100% 



It is readily seen that the number completely regenerated at 

 room temperature in forty-eight hours is much smaller than 

 under higher temperature. 



In a recent paper (3) I noted that the rate of regeneration 

 of Hydra viridis is much more rapid than that of Hydra grisea. 

 In connection with this it is interesting to find that when the 

 temperature is raised there is a larger reduction in the time 

 required for regeneration in Hydra grisea than in Hydra 

 viridis. Table 3 is the record of twenty-eight individuals in 

 five experiments. 



Table 3. — Hydra Grisea. 



Temperature. 



26-27° 

 27-32° 



Per Cent Regenerated. 



48 hrs. 



80% 

 70% 



72 hrs. 



100% 

 100% 



