PARTS AND FUNCTIOxVS. 63 



alkali or mineral acid, than red precipitate or aquafortis 

 itself, is nevertheless as mild and bland and inoffensive to 

 the touch or taste as saliva or gum-w^ater, which it much 

 resembles. Consider, I say, these several properties of the 

 digestive organ, and of the juice with which it is supplied, 

 or rather with which it is made to supply itself, and you will 

 confess it to be entitled to a name which it has sometimes 

 received; that of " the chemical wonder of animal nature." 

 Still, we are ignorant of the composition of this fluid, and 

 of the mode of its action ; by which is meant, that we are 

 not capable, as we are in the mechanical part of our frame, 

 of collating it with the operations of art. And this- I call 

 the imperfection of our chemistry ; for, should the time ever 

 arrive, which is not, perhaps, to be despaired of, when we 

 can compound ingredients so as to form a solvent which will 

 act in the manner in which the gastric juice acts, we may 

 be able to ascertain the chemical principles upon which its 

 efficacy depends, as well as from what part, and by what 

 concoction in the human body these principles are generated 

 and derived. 



In the mean time, ought that which is in truth the defect 

 of our chemistry, to hinder us from acquiescing in the infer- 

 ence which a production of nature, by its place, its proper- 

 ties, its action, its surprising efficacy, its invaluable use, au- 

 thorizes us to draw in respect of a creative design ? 



Another most subtle and curious function of animal bod- 

 ies is secretion. This function is semichemical and semi- 

 mechanical ; exceedingly important and diversified in its 

 effects, but obscure in its process and in its apparatus. The 

 importance of the secretory organs is but too well attested 

 by the diseases which an excessive, a deficient, or a vitiated 

 secretion is almost sure of producing. A single secretion 

 being wrong is enough to make life miserable, or sometimes 

 to destroy it. Nor is the variety less than the importance. 

 From one and the same blood — I speak of the human body — 

 about twenty different fluids are separated ; in their sensi- 



