186 Sir John Luhhock [May 9, 



similar series of errors. It is far from improbable that ants may 

 produce sounds entirely beyond our range of hearing. Indeed, it is 

 not impossible that insects may possess a sense, or rather, perhaps, 

 sensations, of which we can no more form an idea than we should 

 have been able to conceive red or green had the human race been 

 blind. Helmholtz and Depretz have shown that the human ear is 

 sensitive 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, vibrations 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 suggestion. 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 ascer- 

 tain whether the ants themselves produced any sounds for the purpose 

 of conveying signs or ideas. 



Professor Tyndall was good enough 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 good enough to set up for me an extremely sensitive 

 microphone ; it was attached to the under side of one of my nests, but 

 though we could distinctly hear the ants walking about, we could not 

 perceive any other sound. 



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

 that ants may be sensitive to, and also themselves produce, sounds 

 which, from the rapidity of their vibrations, or from some other cause, 

 are beyond our range of hearing. 



Having failed, however, in hearing them or making them hear me, 

 I endeavoured to ascertain whether they could hear one another. To 

 determine, if possible whether they have the power of summoning one 

 another by sound, I tried the following experiments. I put out on 

 the board where one of my nests of Lasius flavus was usually fed, six 

 small pillars of wood about an inch and a half high, and on one of 

 them I put some honey. A number of ants were wandering about on 

 the board in search of food, and the nest itself was about 12 inches 

 from the board. I then put three ants to the honey, and when each 

 had sufficiently fed I imprisoned her and put another; thus always 

 keeping three ants at the honey, but not allowing them to go home. 

 If, then, they could summon their friends by sound, there ought soon 

 to have been many ants at the honey. The results were as follows : — 



We began to watch at 11, and up to 3 in the afternoon only seven 

 ants had found their Avay to the honey, which was about as many as 

 ran up the other pillars. The arrival of these seven, therefore, was 



