298 DIGESTION 



A very intense putrefactive process has often been observed in animals with 

 a biliary fistula, and on this ground it has been assumed that the bile is a pow- 

 erful antiseptic. But this conclusion is not correct ; for in the first place it has 

 been shown by direct experiments that bile is not a good antiseptic reagent, 

 although it does exert an adverse influence on the development of certain Bac- 

 teria for a short time; and in the second place, animals with a biliary fistula 

 which receive little or no fat but plenty of other food, do not, in spite of the 

 diversion of the bile, experience any more putrefaction in the intestine than do 

 normal animals. The loss of bile is therefore not of itself the cause of the putre- 

 faction, when the diet is not exactly regulated. It is rather to be explained by 

 the scanty absorption of fat; for when fat remains in the intestine as a foreign 

 body, it affords a good culture medium for all kinds of Bacteria, which multiply 

 prodigiously and produce an intense putrefaction, and through this a severe 

 intestinal catarrh. 



The same thing happens with new born children when they are fed with 

 starches. The starch is incompletely digested in the intestine, it remains there 

 as a foreign body and an offensive diarrhea develops, notwithstanding the pres- 

 ence of bile. 



A large part of the small intestine can Ite removed from man as well as 

 from animals, and digestion will not be interfered with to any considerable 

 extent. After the removal of 3.1 m. of the intestine of a man, however, the 

 intestinal evacuations were more abundant and the utilization of proteid was 

 less than normal (Riva-Rocci). In the dog only slight permanent changes 

 made their appearance, when as much as seventy per cent of the intestine 

 was extirpated; although the diet had to be carefully regulated and an excess 

 of fat especially avoided (Erlanger and Hewlett). 



4. FORMATION OF FJECES AND DEFECATION 



Digestion is continued in the large intestine by enzymes carried in with 

 the intestinal contents. In the dog, digestion in this part of the alimentary 

 canal appears to be of little importance, since complete removal of the large 

 intestine reduces the absorption of foodstuffs but slightly. The proteids only 

 are less perfectly utilized than normally (Harley). 



In herbivorous animals the large intestine must play a more important 

 part, for in the horse, for example, the cascum is two to three times as large 

 as the stomach. And yet rabbits from which the cagcum is removed live for 

 months without showing any permanent disorder in the digestion or in the 

 general health (Hultgren and Bergman). 



The chief function of the large intestine is to provide for the absorption 

 of foodstuffs capable of being absorbed which have not already been cared 

 for by the small intestine, and by withdrawal of water to reduce the residue 

 to a firmer consistency. The intestinal contents thus transformed are then 

 finally voided from the body as the faeces. 



The fceces contain some undigested constituents of the food, some unab- 

 sorbed products of digestion, putrefaction and fermentation in the intestine, 

 dead intestinal epithelium and residues of the digestive fluids, and finally 

 substances which are given off by the wall of the alimentary canal as excre- 



