INTERNAL ANATOMY OF INSECTS. 143 
secretion, many of the properties of lac are not very 
different from those of the juices of the trees on which 
the animal feeds, and which therefore would seem to 
undergo but little alteration. 
Wax seems also to form a constituent part of some 
insects which are not found to secrete it. The yellow 
substance deposited in vessels containing spiders in al- 
cohol is said to be a true isoax, and may be obtained from 
these animals by gently heating them a . 
ix. Poisons and Acids. The bite as well as the sting 
of many insects is followed by inflamed tumours, so that 
the sialisteria of some bugs, Diptera, Aptera and spiders, 
may be regarded as producing a poisonous fluid ; but 
we know nothing of the real nature of it, nor of that of 
other venomous insects, except the ant — whose celebra- 
ted acid may be considered under the present head, — 
the bee, the wasp, and the scorpion. 
Contrary to the once received doctrine that no acid 
was to be found in any animal, except as the effect of 
disease in the alimentary canal, many insects secrete pe- 
culiar and powerful ones. I have on a former occasion 
related an instance in which an acid of this description, 
secreted in its sialisteria, is employed by a moth to soften 
its cocoon b ; and Lister mentions a species of lulus which 
produced one resembling that of ants c ; but this last is 
the most powerful of all. The fact that blue flowers 
when thrown into an ant-hill become tinged with red 
has been long known; but Mr. Fisher of Sheffield, about 
1670, seems to have been the first who ascertained that 
this effect is caused by an acid with which ants abound, 
and which may be obtained from them by distillation or 
a Nicholson's Journ. i. 298—. b Vol. III. 281. 
' Philos. Trans. 1G70. 
