28 



ELIZABETH LOCKWOOD THOMPSON 



TABLE V 



Showing the number of reactions of the mouths of two individuals of Physa gyrina 

 Say, resulting from the simultaneous application of food and pressure after the 

 complete disappearance (Table IV) of the effect of the association established 

 between these two stimuli (Table III). The tests were made in filtered water 

 on alternating days. The snails had been starved for 24 hours preceding the tests. 



