THE ABSORPTION OF THE FOOD-STUFFS 849 



fistula the expulsion of food occurs at repeated intervals, but in a 

 somewhat irregular fashion, its movements being determined partly 

 by the contractions of the stomach and partly by those of the duo- 

 denal wall. Usually a large gush is followed by a series of small gushes. 

 Although only a foot intervenes between the duodenal fistula and 

 the pyloric fistula, a great difference is observed in the character of 

 the intestinal contents obtained in the two cases. The outflow from 

 the duodenum, being mixed with the pancreatic juice and the bile 

 is yellow in colour and increased in amount. With a meal of 200 grm. 

 there is secreted on the average 130 grm. of bile and 140 grm. of pancreatic 

 juice. During its passage through the duodenum the carbohydrates 

 of the food undergo considerable changes, so that even one foot 

 below the pylorus we find that one-half to three-fifths of the carbo- 

 hydrates have been converted into dextrine and sugar. A further 

 digestion of the proteins also takes place amounting to about one- 

 tenth of the whole protein taken with the food. 



On deducting the amount of juices which have been added to 

 the food it is found that even over this short length of intestine absorp- 

 tion has taken place of about one-sixth of the ingested food, about 

 one-fourth of the carbohydrates having been absorbed and about 

 one-eighth of the proteins. 



In a dog with a fistula about the middle of its small intestine, 

 the outflow began six to fifteen minutes after the meal, and lasted 

 six or seven hours. The outflow was by small gushes repeated at 

 intervals of five to ten seconds separated by intervals of one to five 

 minutes, during which nothing appeared at the orifice of the cannula. 

 The material obtained was quite different in character from that 

 flowing from the duodenal fistula. The pasty character had dis- 

 appeared, the material forming a frothy, orange-yellow, even jelly- 

 like mass with practically no trace of undigested bread. 



From a fistula in the ileum the outflow occurred at long intervals 

 of three to fifteen minutes and was much scantier than that obtained 

 from the jejunal fistula, consisting of a thick jelly-like, orange- 

 coloured mass. Both proteins and carbohydrates were entirely 

 digested, and in the case of the former the chief products of digestion 

 consisted of amino-acids. Thus in one experiment, after four large 

 meals of 500 grm. of meat each had been given, in order to obtain 

 sufficient quantity for analysis, 175 grm. of soluble substances were 

 obtained. From this were isolated tyrosine, leucine, alanine, aspartic 

 acid, lysine, and traces of arginine and histidine. 



From a fistula in the caecum there was no outflow until four or 

 five hours after the meal had been taken. The material from the gut 

 was then extruded in fsecal-like masses at long intervals of one-half 

 to one hour. This regular outflow lasted for about six hours. The 



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