7° 



The Animal Mind 



tacles and by contraction of the stem. This behavior 

 may be called a negative or avoiding reaction, and no 

 positive reaction to a mechanical stimulus has been ob- 

 served. The food-taking reaction, on the other hand, 

 consists in the seizing of the food by the tentacles. It 



seems to be given in re- 

 sponse to a combination 

 of chemical with me- 

 chanical stimulation, 

 such as is offered by con- 

 tact with a solid edible 

 object (751 a). Shall 

 we say that Hydra pos- 

 sesses, then, a food 

 sensation and a con- 

 tact sensation that are 

 distinguishable in its 

 consciousness, provided 

 such consciousness ex- 

 ists? It may be that 

 the contrast between 

 the two is more nearly 

 analogous to that be- 

 tween pleasantness and 

 unpleasantness in our own experience, for the food- 

 taking reaction in Hydra is the only form of the positive 

 reaction, and the response to mere contact is distinctly 

 negative in character. The influence of physiological 

 condition in Hydra's reactions is shown by the fact that 

 although ordinarily the food response is brought about 

 only by contact with food, if_Jhe_iuiimaL...is.,^vSi:^~-hun- 

 grv aj ttv chemi caI...atim]iIation, even quini ne, will produce 

 it~(75ia)- This blunting of discrimination has, of course, 



Fig. 6. — Hydra, mth, mouth; /, tentacle. 

 After Parker. 



