344 THE VITAL FUNCTIONS. 



as an example the elytra of cantharides, which 

 are such active stimulants when applied in 

 powder to the skin in the ordinary mode of 

 blistering ; we find that, notwithstanding their 

 highly acrid qualities, they constitute the natural 

 food of several species of insects, which devour 

 them with great avidity; and yet the fluids of these 

 insects, though derived from this pungent food, 

 are perfectly bland, and devoid of all acrimony. 

 Cantharides are also, according to Pallas, the 

 favourite food of the hedge-hog ; although to 

 other mammalia they are highly poisonous. It 

 has also been found that even those animal 

 secretions, (such as the venom of the rattle- 

 snake,) which, when infused, even in the minutest 

 quantity, into a wound, prove instantly fatal, 

 may be taken into the stomach without produc- 

 ing any deleterious effects. These, and a mul- 

 titude of other well-known facts, fully prove 

 how completely substances received as aliment 

 may be modified, and their properties changed, 

 or even reversed, by the powers of animal 

 digestion. 



No less remarkable are the transmutations, 

 which the blood itself, the result of these pre- 

 vious processes, is subsequently made to undergo 

 in the course of circulation, and when subjected 

 to the action of the nutrient vessels and secret- 

 ing organs ; being ultimately converted into the 



