132 Transactions of the Royal Microscopical Society. 
auditory, we may easily conjecture that they would be able to ap- 
preciate notes in a higher key. The nerve in this antenna is well 
seen, throwing off branches to the organs in its course upwards.” * 
For elf also describes these curious organs with some further 
details. He appears to consider that the number varies considerably, 
namely, from 5 to 12. My own impression is that this difference 
is only apparent, and that in reality the numbers in each species 
vary little. Though sometimes the presence of air renders them 
very conspicuous, they are in others by no means easy to make out ; 
and I think that when a small number only are apparently present, 
this is probably due merely to the fact that the others are not 
brought out by the mode of preparation. 
In addition to the group of these organs situated in the terminal 
segment, there is one, or in some rare cases I have found two, in 
each of the small preceding segments. The tubes in these segments 
appeared to the eye to be nearly of the same length as those in the 
terminal segment, but I could not measure their exact length, as 
they do not lie flat. In some cases, when the segment was short, 
the tube was bent — an indication, perhaps, that the exact length 
is of importance. It is possible that these curious organs may 
he auditory, and serve like microscopic stethoscopes. Professor 
Tyndall, who was good enough to examine them with me, concurred 
in the opinion that this was very probable. I believe I am correct 
in saying that the bending of the tube in the short segments 
would make little difference in its mode of action. 
As mentioned, indeed, in the ‘ Linnean Journal ’ (vols. xii. and 
xiii.), I have never succeeded in satisfying myself that my ants heard 
any of the sounds with which I tried them. “ I have over and over 
again made the loudest and shrillest noises I could, using a penny 
pipe, a dog- whistle, a violin, as well as the most piercing and 
startling sounds I could produce with my own voice, without effect.” 
At the same time I carefully guarded myself against inferring from 
this that they are really deaf, though it certainly seems that their 
range of hearing is very different from ours. 
There are indeed some observations on record which certainly seem 
to indicate that ants possess the power of hearing. Thus, though 
M. Forel believes that ants possess no power of hearing, several of 
his very interesting observations point in the opposite direction. 
For instance, on one occasion an army of Amazon ants ( Polyergus 
rufescens ) was making an expedition to attack a nest of F. rufi- 
barbis. They were not, however, quite acquainted with the locality. 
At length it was discovered: “aussitot,” he observes, “un nouveau 
signal fut donne et toutes les amazones s’elancerent dans cette 
direction.” On another occasion he says: “ Je mis un gros tas 
* ‘ Trans, of Linnean Soe.,’ p. 391, vol. xxii. 
t ‘ Fourmis de la Suisse,’ p. 301. 
