DIGESTION 263 



tuberculosis of the mesenteric glands, that any great 

 arrest of absorption seems to occur. 



The importance of the colon in the absorption of water 

 is very great. As the contents of the ileum pass into 

 the caecum they contain only from 5 to 10 per cent, of 

 solid matter, and as they amount to something like 

 to 1 pint in the twenty-four hours, the activity with 

 which water is absorbed in order to convert them into 

 solid faeces must be very considerable. It is not difficult 

 to understand, therefore, how, in a case in which the 

 contents of the bowel are discharged from an artificial 

 anus without passing through the colon, the patient 

 may easily come to suffer from a defective absorption 

 of water.* 



In addition to water, the colon absorbs some forms 

 of sugar very readily peptone to an appreciable degree, 

 but fats very slightly. Those facts have an important 

 bearing upon the question of rectal alimentation. 



As the result of the combined action of the small and 

 large intestines, it may be taken that the nutritive 

 constituents of an ordinary mixed diet are absorbed to 

 the following extent : 



Proteins ... ... 92 per cent. 



Fats ... ... ... 94J 



Carbohydrates ... ... 98J 



But the exact amount of absorption varies greatly with 

 the composition of the diet. 



The fate of the protein and carbohydrate absorbed 



* See Monier-Williarns, 'The Importance of the Colon,' Brit- 

 Med. Journ., 1906, 787. 



