96 The Animal Mind 



larvae about an ant returning laden to the nest is a stimulus 

 to her nest mates to follow her ; that this smell is stronger, 

 the larger the stock she has found, and hence acts as a more 

 powerful stimulus. The question arises, however, as to 

 how an ant can distinguish between the smell of food or 

 larvae on an ant that has just found a store of either, and 

 the smell of the food and larvae in the nest, which must ad- 

 here to all her nest mates. Some peculiarity of behavior on 

 the part of the foraging ant would seem to be needed if 

 she is to induce her fellows to accompany her to food. 

 Wheeler, whose knowledge of ants is unsurpassed, but who 

 is perhaps a little too much inclined to humanize them, 

 says (783, page 535), " I believe that no one who has watched 

 ants continuously and under a variety of conditions will 

 doubt that they actually communicate with one another. 

 This is clearly indicated by the rapidity with which they 

 congregate on a spot where one of their number has found 

 food, or retire from any spot in which a few of their num- 

 ber have been killed or injured." Such communication, 

 whatever its nature, concerns us here only so far as smell 

 may be involved in responding to it. 



25. The Use of Smell in Path-finding by Ants 



The homing of ants is a puzzling problem. Bethe (51) 

 thinks that ants, as reflex machines, are drawn along the 

 path back to the nest by the chemical stimulus deposited 

 on the path by their own bodies. Pieron (579) has main- 

 tained that in some species we have to do with a kind of 

 muscular memory, the ants simply reversing, on the home- 

 ward path, all the turnings they took on the way out, like 

 a top unwinding itself. Cornetz (143, 144, 145) claims 

 for ants the mysterious power of registering in their bodies 



