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 in 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 been traced to any special secreting organ, but 

 seem to be diffused throughout the system. Vaquelin 

 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, 

 tliat in tropical countries ants are to be met with 

 (Gen. Ponera) armed with stings, which inflict 

 painful a wound as those of bees. Gallic acid has 

 been obtained from the grain weevil, ( Calandra gran- 

 aria) 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 enc 

 of their cocoons, when they wish to obtain egress. 



In the absence of special secreting vessels, tho 



