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The Senses of the Lower Animals . 
[July, 
as it may seem at first glance, is a great convenience to the 
spider, whose enemies — such as birds and certain wasps 
are sure to attack from above, and whose cell or hiding-place 
is generally underneath the web. From our own observa- 
tions we do not think that the sight of spiders has a verv 
long range. 
Insects are sometimes led astray by their unaided sight. 
The “ humming-bird hawk-moth” has been seen examining 
artificial flowers on a lady’s bonnet, and even the coloured 
designs on walls, —a fact which confirms the attractive 
influence of colour upon insects, and corroborates Mr. Dar- 
win’s views on the fecundation of flowers. 
The light-organs of snails offer most interesting peculiar- 
ities. In the genus Oncidium , found in the Philippine 
Islands, and recently studied by Dr. Semper, there are upon 
the back small specks, which are in reality eyes, essentially 
similar in structure to those of vertebrate animals, and 
quite distinct from the well-known tentacular eyes. What 
may be the difference of function in the two organs has not 
yet been ascertained. 
Passing to the sense of smell, we may be met at the very 
outset by the inquiry whether insects have any perception 
of odours at all ? This question is of great moment in the 
general economy of organic Nature. According to several 
modern investigators, among whom we may especially men- 
tion Darwin, the fecundation of flowers, and consequently 
the propagation of vegetable species, depends in a large 
number of cases upon the intervention of moths, butterflies, 
bees, and other insects, which convey the pollen from the 
male organs of one flower to the female organs of another. 
These creatures are attracted to blossoms, in some cases of 
brilliant colour and in others of odour, this being in fact the 
final cause of such beauty and fragrance. If, therefore, 
insects are not endowed with the sense of smell, one part, 
at any rate, of this theory must be given up, and the per- 
fume of flowers must — as far as the welfare of the plant 
itself is concerned — be pronounced purposeless. It will 
therefore be useful to review the evidence which proves the 
existence of an acute and delicate odour-sense in insects, 
the more as a recent experiment has been by some writers 
supposed to demonstrate its absence. 
We will first glance at some of “ Nature’s scavengers,” 
such as the sexton-beetle and the dung-beetles. One of the 
most familiar facts in the economy of these creatures is the 
ease and certainty with which they discover their quarry. 
On a calm spring evening nothing is more common than to 
