COLLEGE ZOOLOGY 





J The reactions of A meba 

 """"* to stimuli are of un- 

 doubted value to the individual 

 and to the preservation of the race, 

 for the negative reaction is in most 

 cases produced by injurious agents 

 such as strong chemicals, heat, and 

 mechanical impacts, whereas posi- 

 tive reactions are produced usually 

 by beneficial agents. The responses, therefore, in 

 the former cases carry the animal out of danger, 

 in the latter, to safety. 



Ameba is of fundamental interest to animal psy- 

 chologists, since it represents the " animal mind " 

 in its most primitive form. Whether or not the 

 animal is in any degree conscious is a question still 

 unanswered. If Ameba has recognizable sensations, 

 they must be infinitely less in both quality and 

 quantity than those of higher organisms. Further- 

 more, it is unable to learn from the few kinds of 

 experiences it does pass through, and is therefore 

 lacking in memory images. 



A review of the facts thus far obtained seems to 

 show that factors are present in the behavior of 

 Ameba " comparable to the habits, 

 reflexes, and automatic activities of 

 higher organisms," and " if Amceba 

 were a large animal, so as to come 

 within the everyday experience of 

 FIG. 15. Phototropism human beings, its behavior would at 



of Ameba. The arrows mdi- . . r 



once call forth the attribution to it of 

 states of pleasure and pain, of hunger, 



The arrows indi- 

 cate the direction of the light 

 rays and the numbers the 

 successive positions assumed 



by the animal. The Ameba desire, and the like, on precisely the 

 same basis as we attribute these things 



always moves away from 

 the source of light. (From 

 Jennings, after Davenport.) 



to the dog." 



