438 OF ABSORPTION AND SANGUIFICATION. 



has ascertained that if albuminous or gelatinous compounds be heated with solid 

 hydrate of potash, and the heat be continued until the greater part or the whole 

 of the nitrogen has been dissipated as ammonia, and hydrogen begins to be given 

 off, the residue, when supersaturated with dilute sulphuric acid, and distilled, 

 yields a liquid containing acetic and butyric acids, and possessing in a very 

 intense degree the peculiar and characteristic odor of human feces. The odor 

 varies according to the substance employed; and in this way all varieties of fecal 

 smell may be obtained. As the action of caustic potash at a high temperature 

 is simply a limited or incomplete oxidation or combustion, this curious result con- 

 firms the view which had been previously put forth by Prof. Liebig, that the 

 proper fecal matter is the product of the imperfect oxidation which a portion of 

 the histogenetic constituents of the food undergo in the course of their regressive 

 metamorphosis, being comparable to the soot or lamp-black of a furnace or lamp. 

 It is further urged by him, that the condition of the feces differs in many particu- 

 lars from that of substances in a state of fermentation or putrefaction ; that their 

 peculiar odor is entirely unlike any that is generated by the ordinary decompo- 

 sition of organic compounds, whether azotized or non-azotized ; and that, by 

 contact with air, they themselves undergo a sort of fermentation or putrefaction, 

 in which their peculiar fetor disappears a fact, as he justly remarks, which is 

 full of significance. 1 This view is of great practical importance ; for if it be true 

 that the intestinal canal receives and discharges the products of the secreting 

 action of a glandular apparatus, whose special function is the elimination of 

 certain products of decomposition from the blood, the facility with which we 

 can stimulate this to increased action by certain kinds of purgative medicine, 

 gives us a most valuable means of augmenting its depurative action. Seeing, 

 as no observant Medical Practitioner can avoid doing, how frequently Nature 

 herself employs this means of eliminating morbific matter from the system 

 as shown by the immense relief often given by an attack of diarrhoaa we may 

 look upon this apparatus as one which, like the Liver, the Kidney, or the Skin, 

 may frequently with propriety be stimulated by medicines that have a special 

 action upon it, and one through which some morbific matters may be got rid of 

 more certainly and more speedily than through any other channel. It is not 

 intended by these observations to encourage the system of violent and indiscri- 

 minate purgation ; but to show that purgatives, judiciously administered, often 

 constitute our best means of eliminating injurious matters from the system. 



CHAPTER VIII. 



OF ABSORPTION AND SANGUIFICATION. 



1. Of Absorption from the Digestive Cavity. 



459. So long as the Alimentary matter remains in the digestive cavity, how- 

 ever perfect may be its state of preparation, it is as far from being conducive to 

 the nutrition of the system, as if it were in contact with the external surface. 

 It is only when absorbed into the vessels, and carried by the circulating current 

 through the very substance of the body, that it becomes capable of being appro- 

 priated by its various tissues and organs. Among the higher Invertebrata, we 

 find the reception of alimentary matter into the circulating system to be entirely 



1 See Prof. Liebig's "Animal Chemistry," 3d edit., pp. 148-154. 



