THE PLASTIC BEHAl'lOR OF ANTS. 539 



esses which this involves. At least three different views may be enter- 

 tained on the subject. First, it may be said that ants not only have 

 images or ideas as the result of sensory stimulation, but are able to 

 recall them at will, and to refer them to the past. This would imply 

 that ants, like man, not only have memory ( i^w in the Aristotelian, 

 inciiioria sensitiva, in the scholastic sense ) but also recollection (riyd l n.vr i fft>?, 

 raniiiiscentia). Second, it may be maintained that ants have images 

 only as the result of sensory stimulation, but are unable to call them 

 up at will, much less to refer them to the absent or to the past. This 

 would imply that the insects have sensory association but not recollec- 

 tion. Third, it may be maintained that ants are unable to form images 

 or ideas and are hence devoid of memory. This is really Bethe's view, 

 which will not be discussed, as it obviously contradicts the facts. Of 

 the two other views I believe that the second does not go further than 

 the facts warrant, and is far and away the more plausible. I am unable 

 to find anything in the observations above recorded, or in many others, 

 which the limits of this volume prevent me from presenting, that would 

 compel us to believe that ants can recollect in the true sense of the 

 word. There is, indeed, much doubt as to the existence of such a 

 capacity even in the higher animals (Thorndike ). 'We must admit." 

 as Miss Washburn says, " that it is not easy to prove the possession 

 by any animal of memory in the sense of having ideas of absent objects, 

 rather than in the sense of behaving differently to present objects 

 because of past experience ivith them. The clog shows clearly that he 

 remembers his master in the latter sense by displaying joy at the sight 

 of him. Can we be sure that he has remembered him in the former 

 sense during his absence ; that is, that he has had a memory image of 

 him ? " Although it seems to be necessary to assume that ants have 

 images or ideas, it must not be supposed for a moment that these bear 

 anything but the remotest resemblance to our own. The fact that the 

 ant's sense-impressions are, almost exclusively, those of odors, contacts 

 and vibrations, make it evident that her mental imagery must differ 

 enormously from ours, in which visual and auditory images luxuriate 

 to the almost complete exclusion of others. To appreciate this differ- 

 ence we have only to contrast with our dull powers of olfaction the 

 ants' exquisite perception, recognition and association of odors. A 

 dog that is born deaf and nearly blind would probably resemble an ant 

 rather closely in its psychical processes, but would be inferior in lacking 

 the ant's fine tactile sense and her power of associating tactile with 

 olfactory impressions. 



If this moderate estimate of the memory of ants be correct, it 

 follows that they must be incapable of reasoning of ' focusing the 



