168 
ANATOMY AND PHYSIOLOGY 
parent fluid., of a sweetish taste when first applied to 
the tongue, but speedily producing a sharp burning 
sensation. Its chemical properties have not been 
properly examined ; but according to Fontana, it is 
soluble in water, and when alcohol is added to the 
solution, it is precipitated m the form of a white 
powder, which converts vegetable blue into red. 
Its action is so powerful, that the writer just named 
calculates that a grain in weight would kill a pigeon 
in a few seconds. 
Allied to the preceding, are the acid secretions of 
ants and a few other insects, which, however, have 
not beeu traced to any special secreting organ, but 
seem to be diffused throughout the system. Yaquelin 
and Fourcroy conceived the former to be composed 
of acetic and malic acid, but Suensen has recently 
demonstrated that the earlier chemists were correct 
in regarding it as of a peculiar nature, and that the 
name Formic acid ought therefore to be retained. 
Berzelius gives the following analysis of it ; hydrogen, 
2, 84 ; carbon, 32, 40 ; oxygen, 67, 76. It is some- 
times ejected by the anus ; and Lacordaire affirms, 
that in tropical countries ants are to be met with 
{Gen. Ponerd) armed with stings, which inflict as 
painful a wound as those of bees. Gallic acid has 
been obtained from the grain weevil, ( Calandra gran- 
arid) and what has been named bombic acid from 
the silk-worm. It is probably one of these that is 
employed by certain Lepidoptera to loosen the end 
of their cocoons, when they wish to obtain egress. 
In the absence of special secreting vessels, the 
