Turner, Homing of Ants. 415 



that the ant's mode of learning is not the trial and error but the 

 perceptual mode and that they have memory (Figs. 8, 10, 12, 18). 

 1 freely confess, however, that this seems to me a very unsatis- 

 factory criterion. For this criterion to be of any real value, we 

 would need some way to determine, from the animal's standpoint, 

 what is complicated and what is not; and there is no known way. 



There are, however, other considerations that lead me to 

 believe that ants have memory. In memory w5 usually find a 

 complex impression composed of contributions from more than 

 one sense organ. In the section that precedes this, I have tried 

 to show that home-going ants have a complex impression which is 

 composed of contributions from several sense organs. Now the 

 existence of this complex impression does not necessarily prove 

 the existence of memory, but, it does demonstrate the existence of 

 one of the usual physiological accompaniments of memory. 



Buttel-Reepen ('00) chloroformed some bees and found that 

 they were no longer able to find their way home. This he con- 

 sidered a proof of memory. How, he asks, could they forget 

 unless they had a psychic content to forget. Is it not reasonable 

 to consider cases of "forgetting" that cannot be attributed to 

 injuries received nor to retardation due to fatigue as evidences of 

 memory ^ In my experiments, I frequently met cases of what 

 might be called lapses of memory. Sometimes this would happen 

 on the stage, at others on the island. The ant would move about 

 at random as though it had forgotten the way. These lapses 

 would increase the time ordinarily required for the trip, from one 

 to three minutes. The subsequent trips were made as rapidly 

 and as regularly as before. I have also met with cases of what 

 might be called mistaken identity (Fig. 7). Recall the experiment 

 with two stages, from each of which an incline descended to the 

 island — the case when the ant occasionally went up the wrong 

 incline — and you have a case of this kind. 



Then, too, I have noticed cases which I think reveal ants as 

 using a thing or things as a means of accomplishing a certain end, 

 rather than responding to it as an end. Take the experiment 

 mentioned in the previous section, where a high vertical gap was 

 present between the foot of the incline and the island. The ants 

 were coming repeatedly to the same point and reaching upward 

 for something beyond their reach. In that place, a stack of clean 

 glass slides was placed a little to one side of the path. At once the 



