SELIG HECHT 



241 



The experiments were conducted as previously outlined, except 

 that 5 minutes were allowed between tests. This time has been found 

 sufficient for the complete recovery from a single stimulus. Using a 

 constant exposure of 0.016 second, I determined the minimum inten- 

 sity necessary to ehcit a response at four different temperatures. 

 When the minimum stimulating distance was found, the determina- 



6SO 



IP 



^ 600 



20" 25" 



TemperatOre 



Fig. 6. Relation between the temperature and the minimum intensity neces- 

 sary for stimulation. The points are single determinations for each experiment 

 shown. 



tion was checked at least twice. Table III gives the details of a 

 portion of one such experiment, wholly typical of the others. Proper 

 precautions were, of course, observed for the maintenance of a fairly 

 constant temperature, etc. In this respect Mya is a particularly good 

 experimental animal, because it helps to stir the sea water by means 

 of its own continuous water current. 



