SECRETION. 343 



the bland farina of the potatoe, will produce in 

 another the poisonous extract of the nightshade. 

 Yet all these, and thousands of other vegetable 

 products, differing widely in their sensible quali- 

 ties, agree very nearly in their ultimate chemical 

 analysis, and owe their peculiar properties chiefly 

 to the order in which their elements are arranged ; 

 an order dependent on the processes to which 

 they have been subjected in the system of each 

 particular vegetable. 



In the animal kingdom we observe these pro- 

 cesses multiplied to a still greater extent ; and 

 the resulting substances are even farther removed 

 from the original condition of unorganized matter. 

 In the first place, the food of animals, instead 

 of being simple, like that of plants, has always 

 undergone previous preparation ; for it has 

 either constituted a portion of some other organ- 

 ized being, or it has been a product of organiza- 

 tion ; in each case, therefore, partaking of that 

 complexity of composition which characterises 

 organized bodies. Still, whatever may be its 

 qualities when received into the stomach, it is 

 soon converted by the powers of digestion into 

 ^ milky, or transparent fluid, having nearly the 

 same uniform properties. We have seen that 

 there is scarcely any animal or vegetable sub- 

 stance, however dense its texture, or virulent its 

 qualities, but is capable of affording nourish- 

 ment to various species of animals. Let us take 



