74 



LIBBIE H. HYMAN 



localization of the stimulus partially determines the direction of 

 the response, and the internal conditions in the animal are also 

 partially directive, while in the shock reaction, the stimulus is 



Figs. 12 to 14 Shock reaction of amoeba. 12a, needle applied to center of 

 the animal; b, anterior end contracts, and c, pseudopodia flow out from previous 

 posterior end. 13a, the hay amoeba flowing with a single large pseudopodium; 

 needle applied to center; 6, anterior end contracts powerfully, causing rest of 

 body to bulge; c, new pseudopodia appear at previous posterior end. 14a, the 

 wheat amoeba showing characteristic fan-like advancing ends; needle applied 

 to center; anterior half contracts in b, and new pseudopodium flows out posteriorly 

 in c. 



entirely non-directive, while the internal conditions wholly de- 

 termine what shall be the direction of locomotion. The latter is, 

 I should think, the more generalized type of response, from which 

 a behavior resulting in an avoidance of the stimulating agent 

 would be secondarily derived. 



