752 PHYSIOLOGY 



the whole time that the food remains in the stomach. In the animal with a pyloric 

 fistula, one to two minutes after the meal had been taken, a few drops of alkaline fluid 

 were extruded from the opening. From three to eight minutes after the conclusion 

 of the meal small quantities of clear acid gastric juice were repeatedly extruded. The 

 first admixture of the food with the outflow from the fistula occurred at eight to twelve 

 minutes after the completion of the meal, and after this time the pylorus continued 

 to open at regular intervals of ten to forty seconds, discharging each time a small 

 amount of fluid composed of particles of undigested bread mixed with gastric juice. 

 One and a half hours later the pylorus began to open less regularly and the fluid became 

 of a more pasty consistence, devoid of lumps of undigested bread. In the fourth, 

 fifth, and sixth hours after the meal the pylorus opened only once every one or two 

 minutes, and towards the end of this period the fluid extruded was clear. The follow- 

 ing Table shows the percentage amount of food taken which had left the stomach at 

 the end of each hour after the meal : 



First hour . . . . . .32-6 per cent. 



Second hour . . . . . .17-9 



Third hour ....... 29-5 



Fourth hour 1 87 



Fifth hour 6-66 



Sixth hour 4-21 



The large proportion of the ingested food leaving the stomach during the first two 

 or three hours can hardly be regarded as normal. Since in these experiments there was 

 a free outflow from the pylorus and the food was not allowed to enter the duodenum, 

 the local reflex, evoked by the presence of acid in the duodenum, was absent. The 

 gastric contents obtained in this way were analysed in order to find what changes 

 had been wrought on the food by the gastric juice. It was found that 32 per cent, 

 of the bread had been brought into solution. This solution had affected the proteins 

 more than the carbohydrates. Thus 67 per cent, of the nitrogen had been brought 

 into soluble form, consisting chiefly of proteoses and peptones. No ammo-acids 

 were formed. Only 25 per cent, of the starch of the bread had been rendered soluble, 

 and of this, 21 per cent, was in the form of dextrine and 4 per cent, in the form of 

 sugar. No absorption, however, either of the digested proteins or of the digested 

 carbohydrates was ever found to take place in the stomach. 



DUODENAL DIGESTION. The influence exerted by the pancreatic juice, bile, 

 and succus entericus, poured out on the food in the duodenum, was studied by analysis 

 of the intestinal contents leaving the intestine by a fistula, either at the lower end of 

 the duodenum, or in the jejunum, or in the ileum. From the duodenal fistula Ihe 

 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 duodenal 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 con- 

 siderable changes, so that even one foot below the pylorus we find that one half to 

 three-fifths of the carbohydrates 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 in this short length of intestine absorption 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 



