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 wax, 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 cf 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 5 ; 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 -. h VOL. III. 281. 



c Philos. Trans. 1670. 



