The Senses of the Lower Animals. 
309 
1878.] 
with his wonderful speed and command of wing, and with 
his scarcely less marvellous development of the visual 
organs, has comparatively little need for the sense of smell, 
and his antennae are small and simple. The locust, strong 
on the wing, able as a leaper. and prepared to eat almost 
every green thing upon the face of the earth, has small 
occasion for minute discrimination of odours : his antennae, 
accordingly, are mere bristles. The tiger-beetle — able to 
run, bound, and fly with extreme velocity, and preying upon 
every animal he is able to overcome — needs little delicacy of 
scent, and his antennae therefore are of the same simple 
type. The ground-beetles, though in many cases wingless, 
and in others noCturnal, are willing to feed both on living 
prey or dead animal matter, and in case of need upon cer- 
tain vegetable substances. We need therefore feel little 
surprise that their antennae, too, should be plain in structure. 
The common house-fly is swift and powerful on the wing 
and unlimited in its diet ; it therefore has less need for a nicely 
appreciative scent, and in consequence for highly developed 
antennae. 
On the other hand, the male moth who has to seek both 
his food and his partner, often in the night, has in a majority 
of instances highly developed plumose antennae. The but- 
terfly — who, though feeding on the honey of flowers, does 
not appear to be promiscuously attracted by all plants — has 
antennae furnished at the end with buttons or knobs. The 
common dung-beetle, who crawls slowly and flies heavily, 
and who depends upon one class of substances alone for his 
own food and for the nidus of his offspring, has at the end 
of his antennae a club that opens out in plates, like the 
leaves of a book, and thus exposes a very large amount of 
surface to the action of the atmosphere. 
We may further remark that the antennae in larvae are in 
a rudimentary state, and merely become developed when 
the inseCt has reached the reproductive stage of its 
existence. 
This also is in favour of our view that they are the organs 
of scent — a sense which throughout the animal kingdom 
seems to stand in a close and particular relation to the 
sexual functions. It has been observed that in our own 
species the olfactory nerves are comparatively inactive prior 
to the age of puberty. 
The question has often been raised— -By what means does 
the ichneumon-wasp, or other parasitical inseCt, discover 
the presence of the larvae or pupae destined to become its 
victims, hidden, as the latter frequently are, among closely 
