404 'Journal of Comparative Neurology and Psychology. 



sounds used were produced by a steel bar, a tin whistle, a wooden 

 whistle, a middle A tuning fork and a milled disk rotating against 

 the edge of a card. Fielde and Parker ('04) claim that ants 

 do not react to aerial sound waves from a piano, violin, or Galton 

 whistle; but only to vibrations that reach them through some solid 

 body. 



Recently I have performed a series of experiments upon For- 

 mica fusca var. subsericea Say, and a variety of Formica sanguinea 

 Latr. For these experiments the ants were housed in Janet 

 nests, the covers of which were composed of orange colored glass. 

 During the day, the experiments were never begun until the sun 

 was several hours high; and at night, the experiments were not 

 begun until the electric lights had been shining for at least three 

 hours. These precautions were taken to eliminate the disturbing 

 effects of a change in illumination. To lessen the possibility of 

 jars from the sounding body reaching the nest through any medium 

 other than air, the nests were placed on a layer of cotton batting 

 half an inch thick. For the same reason, the legs of the table on 

 which the nests rested were placed on thick wads of cotton batting. 



The sounds used were produced by the Galton whistle, organ 

 pipes and the human voice. Sometimes the whistle or pipe was 

 held near the nest and in other cases a short distance away. The 

 pipes were always held in such a position that the air when expelled 

 from the pipe could not mipmge directly upon the nest. These 

 experiments were conducted during the winter and early spring. 



They showed conclusively that each of the two species of ants 

 mentioned was sensitive to vibrations of the air which to the human 

 ear would be sounds. I obtained responses to notes as high as 

 4138 vibrations per second and as low as 256 vibrations per second. 

 The responses, in the form of zigzag movements, were usually 

 slight for pitches higher than 3000 vibrations per second and 

 sometimes slight for other pitches; but, to most pitches under 3000 

 vibrations per second, the ants usually responded in a pronounced 

 manner, usually darting about as though much excited. 



After the ants had been subjected to the sounds for a long time 

 they seemed to become fatigued, failing to respond in the least to 

 pitches which would call forth pronounced responses from fresh 

 ants. The fertile females seemed to be more intensely excited 

 by the tones than the neuters. Several series of experiments 

 were performed. Details of four typical series are recorded in 

 the following table. 



