SECRETION. 309 



highly poisonous. It has also been found that even 

 those animal secretions, (such as the venom of the 

 rattle-snake,) which, when infused into a wound, 

 even in the minutest quantity, prove quickly fatal, 

 may be taken into the stomach without producing 

 any deleterious effects. These, and a multitude 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 previous pro- 

 cesses, is subsequently made to undergo in the 

 course of circulation, and when subjected to the 

 action of the nutrient vessels and secreting organs ; 

 being ultimately converted into the various textures 

 and substances which compose all the parts of the 

 animal frame. All the modifications of cellular 

 substance, in its various states of condensation ; the 

 membranes, the ligaments, the cartilages, the bones, 

 the marrow ; the muscles, with their tendons ; the 

 lubricating fluid of the joints; the medullary pulp 

 of the brain; the transparent jelly of the eye; 

 in a word, all the diversified textures of the various 

 organs, which are calculated for such different 

 offices, are derived from the same nutrient fluid, 

 and may be considered as being merely modified 

 arrangements of the same ultimate chemical ele- 

 ments. 



In what, then, we naturally ask, consists this 

 subtle chemistry of life, by which nature effects 

 these multifarious changes ; and in what secret 

 recesses of the living frame has she constructed 

 the refined laboratory in which she operates her 



