INTESTINAL DIGESTION FAECES. 185 



ing 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 

 confirms 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 retrograde metamorphosis, being comparable to the soot or lampblack 

 of a furnace or lamp. It is further urged by him, that the condition of 

 faxx'S differs in many particulars from that of substances in a state of fer- 

 mentation or putrefaction ; that their peculiar odor is entirely unlike any 

 that is generated by the ordinary decomposition of organic compounds, 

 whether azotized or uou-atouized ; and that, by contact with air, they them- 

 selves 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 intesti- 

 nal 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. See- 

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

 Nature herself employs this means of eliminating morbific matter from the 

 system, as is shown by the immense relief often given by an attack of diar- 

 rhoea, we may look upon this apparatus as one which, like the Liver, the 

 Kidney, or the Skin, may frequently, with propriety, be stimulated by medi- 

 cines that have a special action upon it, and one through which some mor- 

 bific 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 indiscriminate purgation ; but to show that purga- 

 tives, judiciously administered, often constitute our best means of eliminating 

 injurious matters from the system. 



132. If we now cast a retrospective glance at the changes undergone by 

 the several groups of substances employed as food in their passage through 

 the alimentary canal, we shall find that, 1. The oleaginous compounds are 

 melted and finely divided in the stomach, and may, under certain conditions, 

 undergo decomposition indicated by acid eructations, etc. On entering the 

 small intestine they are emulsified, and in small part also decomposed by the 

 action of the pancreatic juice and bile, and are gradually almost entirely 

 absorbed before reaching the large intestine. 2. The starchy compounds are 

 converted into dextrin and sugar, first by the saliva, secondly by the pan- 

 creatic juice, and thirdly by the succus entericus. They in part undergo 

 lactic acid fermentation from the mere heat and moisture of the stomach 

 and intestines, and this again is capable of effecting the conversion of other 

 portions of the starch into dextrin and sugar. Ample provision thus exists 

 for the digestion of starchy substances, and they may hence be consumed 

 without harm under circumstances in which the digestion of albuminous 

 compounds or of fats can only be accomplished with difficulty, if at all. By 

 far the larger portion of the starch thus converted into sugar, and almost all 

 the purely saccharine compounds are dissolved and absorbed in the small 

 intestine. ' A considerable quantity of starch , however, if this be eaten raw 

 as in the form of unripe apples or other vegetables, passes off by the bowels 

 unaltered ; and this is the case even in the Herbivora, which have very long 



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



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