336 



PROCESSES IN THE LARGE INTESTINE. 



rapidly peristalsis takes place, however, the more watery are the feces, 

 because there is not sufficient time for the absorption of fluid from the 

 rapidly advancing ingesta. Paralysis of the intestinal blood-vessels and 

 lymph- vessels, after transection of the nerves, is likewise accompanied 

 by liquefaction of the feces. 



The reaction of the feces is often acid, particularly in consequence of 

 lactic-acid fermentation of large amounts of carbohydrates ingested. 

 Numerous other acids generated by fermentation are also present. 

 If, however, considerable amounts of ammonia are produced in the lower 

 portion of the intestine, a neutral and even an alkaline reaction may 

 preponderate. The secretion of large amounts of mucus in the intestine 

 favors a neutral reaction. 



E. 



St. 



G. 



SI. 



Mm 



B. 



Lm. 



FIG. 124. Longitudinal Section through the Large Intestine: E, epithelium; St, mucous membrane; G, blood- 

 capillaries; SI, solitary follicles; C, circular muscular layer; Ms, muscular layers; Lm, longitudinal 

 muscular layer; Ld, Lieberkiihn's glands; Mm, muscularis mucosEe; B, connective tissue. 



The odor of the feces, which is more pronounced with a meat-diet 

 than with a vegetable diet, is dependent upon the fecal-smelling products 

 of putrefaction not yet prepared in an isolated state ; further upon the 

 volatile fatty acids, as well as upon traces of methylmercaptan. The 

 last-named substance can be prepared from proteid by means of fused 

 potassium hydroxid, and it develops in traces on boiling varieties of 

 cabbage, and it is also formed from hydrogen sulphid (as from eggs). 



The color of the feces varies in accordance with the amount of altered 

 biliary pigment present, hence shades vary from light yellow to dark 

 brown. 



