CHANGES IX IXTESTIXES. THE FECES. 2 1 I 



again by cautious addition of alkali to the neutral point, but the precipi- 

 tate is not as characteristic as in the first instance. 



Mucin. This was formerly supposed to be a common and abundant 

 product in normal feces, but this is not the case. Pathologically mucin 

 may be present so as to be recognizable by the eye. A good chemical 

 test for small amounts is still lacking. 



Nucleo-proteid. By extracting normal feces with lime water and acidi- 

 fying with acetic acid, a bulky precipitate is obtained usually, which was 

 supposed to be mucin. It, however, contains phosphorus and belongs to 

 the proteid group. The substance is a normal product in traces and can 

 be found in feces following a diet free from nucleins. It is therefore 

 likely that traces of this protein are brought into the intestines from the 

 breaking down of the intestinal walls. Pathologically much more may 

 be found, but without having a distinct diagnostic indication. 



Of all the protein substances mentioned, the casein, if it 

 occurs in large quantities in infants' feces, has perhaps the 

 greatest importance as pointing to imperfect digestive power. 

 There can be no question, of course, as to its origin. Serum 

 or egg albumin as such could rarely be present because such 

 proteins are ordinarily consumed in the coagulated condition. 

 AYhen the tests point to the presence of a true soluble albumin 

 the result shows probably the entrance of albumin from the 

 blood by a reversal of the normal osmotic process. It must 

 be remembered, however, that true albumin is very rarely 

 found in the feces. Occasionally a reaction due to presence 

 of pus or blood may be obtained, but the albumose or peptone 

 reactions are much more frequent. In diarrhoea stools, for 

 example, where insufficient time is given for absorption, these 

 bodies may be found. 



Insoluble Proteins. The detection of coagulated proteins 

 and of partly disintegrated albuminoids is practically impos- 

 sible. Remains of muscle fibers or other complex substances 

 essentially protein may sometimes be recognized by the micro- 

 scope, but they are beyond chemical identification. 



OTHER NORMAL AND ABNORMAL SUBSTANCES. 



It will not be necessary to discuss the occurrence of the 

 various putrefactive bodies of bacterial origin which are al- 

 ways found in the feces. \Ye have here indol, skatol, various 



