4o8 JoiiDwl of Comparative Neurology and Psychology. 



I have taken even more precautions to preclude the possibihty of 

 the vibrations reaching the ants through a solid medium than 

 they did. The only precaution they took was to rest the nest upon 

 a thick layer of paper. I carpeted my nests with two layers of 

 thick felt, placed a thick layer of cotton between the nest and the 

 Lubbock island and thicker wads of cotton beneath the legs of 

 the table upon which the island rested. The lowest note of the 

 whistle used by Fielde and Parker was 10,000 vibrations per 

 second, which is far above the highest pitch to which ants respond. 

 The whistle I used ranged from 3480 to 51,000 vibrations per 

 second. If the sound of the piano and of the violin were common 

 in the room where the ants were kept they may have become too 

 familiar to arouse responses. My ants were kept in a room fac- 

 ing a paved street. The noises of this street did not disturb 

 them. 



The more I meditate on Fielde and Parker's paper, the more 

 I am inclined to believe that the lack of harmony between their 

 results and mine is due to the difference in our technique. In 

 their experiments the same note was sounded ten times in slow 

 succession; in mine each note was sounded continuously or else 

 in rapid succession for one minute or longer. I thought that, if 

 ants can hear, the occasional production of a note might simply 

 attract attention, while a continuous rapid repetition of the same 

 would arouse some form of visible motor response. In my own 

 experiments a note repeated a few times in slow succession would 

 often cause no response, yet a prolongation of the sound or a con- 

 tinuous rapid repetition of the same would soon produce marked 

 responses. If this contention be valid, we would expect Fielde 

 and Parker's technique to yield nothing more than an occasional 

 response. And this is the result they obtained; for on page 643 

 {loc. cit.) they say, "Now and then an ant would seem to respond 

 to a given note, but in every case repetitions of the experiment 

 gave a negative result. 



Responses to light within and without the nest exhibit differ- 

 ences similar to those observed for sound. If light is admitted 

 into a nest, the ants at once are much disturbed and show it by 

 vigorous movements. Yet in the outer world, so long as the 

 direction of the rays remains the same, ants are scarcely, if at all, 

 affected by changes in the intensity of the light. Both light and 

 sound are almost constant factors of the external world, but are 



