402 'Journal of Comparative Neurology and Psychology. 



substituted for the old one. This was repeated until all of the 

 colors had been used at least once. All ants were not affected in 

 the same way by these changes. Myrmica punctiventris was 

 slightly affected each time a change in color was made (Fig. 15); 

 another ant (sp. ?) was disturbed by a change from black to 

 white, but not by changes from one member of the color series to 

 another. Formica fusca was not usually disturbed by any changes 

 made but occasionally (Fig. 14) it was slightly disturbed. This 

 shows that changes in color of the pathway do not disturb some 

 ants at all^ whereas other ants seem to be slightly affected by such 

 changes;" while yet others are affected by changes in brightness 

 but not by changes in hue. 



Experiments with Auditory Stimuli. — This section is not in- 

 tended to be an exhaustive discussion of the auditory sense of ants. 

 It is, however, an attempt to collate our knowledge on the subject, 

 to give additional experimental data and to harmonize the con- 

 flicting views. 



About a century ago St. Fargeau, in his Hist. Nat. des Hyme- 

 nopteres, asserted positively that ants hear (Lubbock '81, p. 221). 

 But HuBER (Nat. Hist, of Ants), Forel (Fourmis de la Suisse) 

 and Lubbock ('81) conducted experiments to test the power of 

 ants to hear and each decided that they were deaf to sounds that 

 fall within the human auditory range. 



Sir John Lubbock's experiments were especially well planned. 

 He used sounds produced by a dog whistle, a violin, the human 

 voice, a shrill penny pipe, and a full set of tuning forks. These 

 experiments were tried both upon ants that were carrying pupae 

 home and upon ants confined to paper bridges. In no case did 

 he get the slightest response to any of the sounds made. Since, 

 however, he had discovered in ants what he thought was an audi- 

 tory organ, he presumed that it was probable that ants both heard 

 and produced sounds; but that they were tones that fell outside 

 of the human auditory range. 



The negative results of the experiments of these three author- 

 ities have caused most people to believe that ants cannot hear. 



5 Lubbock Qoc. cit., p. 198) performed an experiment which showed that the ants studied by him did 

 not notice the color of the path. He placed some ants on a narrow bridge, which was supported by 

 pins with their bases in the water. On this bridge he projected a spectrum and noticed that the ants 

 acted as they did on the plain bridge. 



'' It is not improbable that these disturbances may have been due to a slight difference in the texture or 

 odor of the different papers. 



