124 ON THE HABITS OF ANTS. [lect. 



to. vibrations reaching to 38,000 in a second. The 

 sensation of red is produced when 470 millions of millions 

 of vibrations of ether enter the eye in a similar time ; 

 but between 38,000 and 470 millions of millions, vibra- 

 tions produce on us the sensation of heat only. We have 

 no special organs of sense adapted to them, but there 

 is no reason in the nature of things why this should be 

 the case with other animals, and the problematical organs 

 possessed by many of the lower forms favour the sug- 

 gestion. If any apparatus could be devised by which 

 the number of vibrations produced by any given cause 

 could be lowered so as to be brought within the range 

 of our ears, it is probable that the result would be most 

 interesting. 



I have tried unsuccessfully various experiments in 

 order to ascertain whether the ants themselves produced 

 any sounds for the purpose of conveying signs or ideas. 

 Professor Tyndall was so good as to arrange for me one of 

 his sensitive flames, but I could not perceive that it 

 responded in any way to my ants. The experiment was 

 not, however, very satisfactory, as I was not able to try 

 the flame with a very active nest. Professor Bell was also 

 kind enough to set up for me an extremely sensitive 

 microphone : it was attached to the under side of one of 

 my nests, and though we could distinctly hear the ants 

 walking about, we could not distinguish any other 

 sound. 



It is, however, of course possible, as I have already 

 suggested, that ants may be sensitive to, and also them- 

 selves produce, sounds which, from the rapidity of their 

 vibrations, or some other cause, are beyond our range of 

 hearing. Having failed therefore in hearing them or 



