CHAPTER XL VIII 

 THE LARGE INTESTINE 



The Function of the Large Intestine. Recently there has been 

 some discussion as to whether the large intestine performs a 

 useful function. By some surgeons it is regarded merely as a 

 sewer-pipe, in which, as the result of bacterial action, the fer- 

 mentation of carbohydrate and the putrefaction of protein proceed 

 apace, so that he is to be considered a happy man who has rid himself 

 of such an encumbrance (!). Such an opinion flies in the face of 

 Nature and the laws of evolution. The trouble would appear to be 

 that people, while clamouring loudly for modern sanitation, do not 

 trouble to keep this " sewer-pipe " in a wholesome condition. In 

 the large intestine, the greater part of the' ingested water is absorbed 

 into the body. This is curious, considering the disgust such feculent 

 water would give us. It is very doubtful whether any products of 

 digestion are absorbed in the large intestine. It was formerly believed 

 that protein digestion was continued in the large intestine, and that 

 an appreciable absorption of the products was absorbed into the 

 system. Recent researches cast doubt upon this point. It may be 

 that a small absorption of the products of protein digestion takes 

 place. 



In rectal feeding, the nutriment so given is passed back by reversed 

 peristaltic movements into the small intestine, and there digested 

 and absorbed. Within a few minutes of giving an egg enema, the 

 yellow fluid has been seen pouring from a duodenal fistula. 



The absorption of water is of considerable importance to the body 

 It is also of great convenience, since it conduces to the proper forma- 

 tion of faeces and greatly reduces their bulk. As the result of extirpa- 

 tion of the whole large intestine in a dog, it was found that the faeces 

 passed each day were greatly increased in weight, and contained five 

 times the normal amount of water. The absorption of protein was 

 slightly diminished, but not that of carbohydrates and fats. In 

 some way not at present adequately understood, the calcium and 

 phosphatic metabolism is influenced by the large intestine. On a 

 herbivorous diet, the amount of calcium excreted by the large 

 intestine and passed in the faeces is considerably greater than on 

 an omnivorous diet. On this latter diet, the proportion of calcium 

 passed in the faeces compared to the urine is 75 : 25; on a herbivorous 

 diet, the proportion may be 95 to 5. 



The large intestine is the playground of bacteria. The contents 

 afford an ideal culture medium. Its glands secrete an alkaline 



402 



