The Mind of the Simplest Animals 41 



made only in response to edible substances, hence there is 

 doubtless some chemical peculiarity about the stimulus which 

 makes it effective (Fig. 2). 



These three reactions make up, together with the ordinary 

 crawling locomotion, the variety of the Amoeba's experience 

 as displayed in behavior, with the addition of a peculiar set 

 of movements occurring in the absence of all mechanical stimu- 

 lation. When an Amoeba is floating in the water, through some 

 chance, unattached to any solid, "such a condition," says 



FIG. 2. Food-taking reaction of Amoeba, i, 2, 3, 4, successive stages. 

 After Jennings (211). 



Jennings, "is most unfavorable for its normal activities ; it can- 

 not move from place to place, and has no opportunity to obtain 

 food." Its mode of getting out of the difficulty is to send out 

 "long, slender pseudopodia in all directions," until "the body 

 may become reduced to little more than a meeting point for 

 these pseudopodia" (211, p. 8). As soon as one of these 

 "feelers" comes in contact with a solid, it attaches itself, and 

 the whole animal following soon takes up its normal crawling 

 locomotion. 



9. The Mind of Am&ba 



Now what light does the behavior of Amoeba, thus described 

 in its various forms by Jennings, throw upon the nature of the 



