PHYSIOLOGICAL SENESCENCE IN HYDROMEDUS/E. 



59 



minutes, or after very strong stimulation an hour or two before 

 return to the usual form and resumption of pulsation occur. 

 As in JEquorea, the ability to contract persists long after the 

 ability to pulsate has disappeared. 



In Table V. the chief data obtained with HC1 are given. 

 They are essentially similar to those for 



TABLE V. 



Mitrocoma: SUSCEPTIBILITY TO HC1. 



The first series 5, X. in HC1 772/1500 shows acclimation as re- 

 gards the effect on pulsation rate, pulsation persisting longer in 

 the young than in the old. In Mquorea also some degree of 

 acclimation usually occurs in this concentration (p. 53). The 



