444 
Our Six-footed Rivals. 
[October, 
But there is another channel of communication which 
deserves to be carefully investigated. We know that the 
language of vertebrates, or at least of their higher sections, 
turns on the production or recognition of sounds. What if 
the language of social inseCts should be found to depend, in 
part at least, on the production and recognition of odours ? 
We have already full proof that their sense of smell is 
developed to a degree of acuteness and delicacy which utterly 
passes our conceptions of possibility, and to which the scent 
of the keenest hound presents but a very faint approxima- 
tion. Collectors of Lepidoptera are well aware that if 
a virgin female moth of certain species is enclosed in a box, 
males of the same species will make their appearance from 
distances which may be relatively pronounced prodigious. 
As soon, however, as the decoy has been fecundated this 
attraction ceases. This is only one among the many phe- 
nomena which testify to the wonderful olfaCtory powers of 
inseCts. So much, then, for the recognition of odours. 
Nor is their production among inseCts a matter open to doubt. 
Scents, distinctly perceptible even to our duller organs, are 
given off by many. The pleasantodourof themusk-beetle, and 
the offensive smells of the ladybirds, the common ground- 
beetles, the oil-beetles, the Spanish fly, and the “ devil’s 
coach-horse ” — hence technically named Gcerius olens — 
are known to every tyro in entomology. The next question 
is, Are these odours at all under the control of the inseCt, 
and capable of being produced, suppressed, or modified at 
will ? We have noticed many instances where the odours 
of inseCts became more intense under the influence of anger 
or alarm. A peculiarly pungent odour is said to issue from 
a bee-hive if the inmates are becoming excited. 
The possibility of a scent-language among inseCts must 
therefore be conceded. Mr. Belt thinks that the Ecitons 
mark out a track which is to be followed by t4i e i r comrades 
by imparting to it some peculiar odour. He says : — “ At 
one point I noticed a sort of assembly of about a dozen 
individuals that appeared in consultation. Suddenly one 
ant left the conclave, and ran with great speed up the per- 
pendicular face of the cutting without stopping. It was 
followed by others, which, however, did not keep straight 
on like the first, but ran a short way, then returned, and 
then again followed a little farther than the first time. 
They were evidently scenting the trail of the pioneer, and 
making it permanently recognisable. These ants followed 
the exaCt line taken by the first one, though it was far out 
of sight. Wherever it had made a slight detour, they did 
