PROCESSES IN THE LARGE INTESTINE. 377 



It is of the utmost importance, in connection with the processes of 

 putrefaction, to determine whether they take place when oxygen is 

 excluded or not (Pasteur). When is absent, reductions take place ; 

 oxy-acids are reduced to fatty acids, and HCH 4 and H 2 S are formed; 

 while the H may produce further reductions. If be present, the 

 nascent H separates the molecule of free ordinary oxygen ( = 2 ) into 

 two atoms of active oxygen ( = 0). Water is formed on the one hand, 

 while the second atom of is a powerful oxidizing agent (Hoppe- 

 Seyler). 



[It is not improbable that some substances, as sulphur, are in part rendered 

 soluble and absorbed by the action of the nascent hydrogen evolved by the 

 schizomycetes, forming a soluble hydrogen compound with the substance (Matthew 

 Hay).] 



It is remarkable that the putrefactive processes, after the development of 

 phenol, indol, skatol, cresol, phenylpropionic and phenylacetic acids, are after- 

 wards limited, and after a certain concentration is reached they cease altogether. 

 The putrefactive process produces antiseptic substances which kill the micro- 

 organisms (Wernich), so that we may assume, that these substances limit to a 

 certain extent the putrefactive processes in the intestine. 



The reaction of the intestine immediately below the stomach is acid, 

 but the pancreatic and intestinal juices cause a neutral and afterwards 

 an alkaline reaction, which obtains along the whole small intestine. 

 In the large intestine, the reaction is generally acid, on account of the 

 acid fermentation and the decomposition of the ingesta and the feces. 



185. Processes in the Large Intestine. 



Within the large' intestine, the fermentative and putrefactive pro- 

 cesses are certainly more prominent than the digestive processes proper, 

 as only a very small amount of the intestinal juice is found in it 

 (Kiihne). The absorptive function of the large intestine is greater than 

 its secretory function, as at the beginning of the colon, its contents are 

 thin and watery, but in the further course of the intestine they become 

 more solid. Water and the products of digestion in solution are not 

 the only substances absorbed, but under certain circumstances, un- 

 changed fluid egg-albumin (Voit and Bauer, Czerny and Latschen- 

 berger), milk and its proteids (Eichhorst), flesh- juice, solution of 

 gelatin, myosin with common salt, may also be absorbed. Experi- 

 ments with acid-albumin, syntonin, or blood-serum gave no result. 

 Toxic substances are absorbed more rapidly than from the stomach 

 (Savory). The fsecal matters are formed or rather shaped in the lower 

 part of the gut. The cajcum of many animals, e.g., rabbit, is of con- 

 siderable size, and in it fermentation seems to occur with considerable 

 energy, giving rise to an acid reaction. In man, the chief function of 



