THE LARGE INTESTINE AND ITS CONTENTS. 187 



fluid ; and if a loop of the gut itself be isolated by ligatures, an accumu- 

 lation of mucus-like matter is the only result. In the rabbit, however, 

 after ligature of the vermiform appendix, Funke obtained, at the end of 

 from two to four hours, a quantity of a turbid alkaline secretion, with 

 which the appendix had become filled. This fluid was without action 

 upon coagulated albumen ; but it transformed starch into sugar, and 

 also decomposed the sugar, with production of lactic and butyric acids. 

 The same change was produced upon starch introduced into the cavity 

 of the appendix. 1 This accounts for the acid reaction sometimes found 

 in the caecum of herbivorous animals, from the decomposition of undi- 

 gested starch, although the mucous surface of the large intestine is 

 constantly alkaline. 



As the remnants of the alimentary mass pass the situation of the 

 ileo-csecal valve and enter the large intestine, they begin to acquire a 

 more pasty consistency and a peculiar repulsive odor. Both these 

 changes become more marked in the middle and lower part of the gut, 

 until all the superfluous fluids have disappeared, and the consistency 

 and odor of the feces are fully developed. This odor is not a putrefac- 

 tive one, but is characteristic of the contents of the large intestine. Its 

 source may be either a peculiar transformation of some of the ingre- 

 dients of the food, or an excretory action of the mucous membrane of 

 the intestine. It is probably in great part the result of an excretion, 

 since in different kinds of animals, whatever be the nature of their food, 

 the feces have usually a distinct odor characteristic of the species. 



The average daily quantity of the feces in the human subject is 150 

 grammes, of which about 75 per cent, is water, and 25 per cent, solid 

 residue. They consist, first, of the undigested remnants of the food ; 

 and, secondly, of the excreted materials from the alimentary canal. 

 The undigested substances derived from the food are mainly animal or 

 vegetable tissues, which, from their constitution, are incapable of diges- 

 tion. These are elastic fibres, or bits of elastic tissue, which nearly 

 always pass the intestine unchanged ; shreds of tendon or fascia, not 

 sufficiently softened by cooking ; horny epidermic tissues, both animal 

 and vegetable ; and the spiral tubes and ducts of vegetable substances. 

 The excreted materials of internal origin are the mucus of the large 

 intestine, and probably also the volatile substances which produce the 

 fecal odor. The coloring matters of the bile are present in a more or 

 less altered form. 



The mineral salts contained in the feces amount to a little over one- 

 tenth of the solid ingredients. They are, for the most part, the same 

 with those common to the animal fluids in general, but are mingled in 

 different proportions ; only about 4 per cent, consisting of the soluble 

 chlorides and sulphates, while fully 80 per cent, are composed of lime 

 and magnesium phosphates. They are regarded as mainly derived from 



1 Kanke, Physiologic des Menschen. Leipzig, 1872, p. 297. 



