Alimentary Jract and the Influence of Bacteria present. 9 



alimentary canal were added. This mixture was rendered alkaline 

 with sodium carbonate, and then just made acid by the cautious 

 addition of acetic acid until the neutral point was passed. The 

 mixtures were then kept at 38° C. for four hours. A check 

 experiment with liquor pancreaticus in place of the contents showed 

 that it could digest 68*5 per cent, of the albumin in a slightly acid 

 solution. The amounts digested by the intestinal contents varied 

 from 48 per cent, in the case of the lower ileum, 37 per cent, in 

 the jejunum, to 17 per cent, in the large intestine. 



A small proportion of free mineral aoid arrested the proteolytic 

 action of trypsin; a larger percentage of hydrochloric acid com- 

 bined with proteids was necessary to cause a corresponding degree 

 of inhibition. 



Pepsin. 



Artificial digestion experiments, in which 5 cub. cm. of the con- 

 tents of each portion of the alimentary canal were added to a 

 mixture containing 0'115 gram of egg albumin and 20 cub. cm. of 

 decinormal HC1, resulted in a certain amount of the albumin 

 being digested in each. Seventy-seven per cent, of the proteid was 

 digested after four hours at 38° C, when 5 cub. cm. of the 

 stomach contents had been added, 20 to 28 per cent, in the experi- 

 ments with the duodenal, jejunal, and upper ileac contents, only 

 12*9 per cent, when the contents of the lower ileum were used, and 

 19 per cent, when the large intestine was tested. 



Pistillate of Contents of Bowel. 



When the contents of a portion of the intestine were distilled 

 after the addition of water, if the combined acidity after evaporation 

 was greater than the total acidity as originally estimated, the first 

 portions of the distillate were alkaline and contained ammonia, 

 even although the contents had been of highly acid reaction. 

 When the acidity after evaporation was lower than before it, as in 

 the stomach and large intestine, the distillate was acid from the first, 

 due, as a rule, to acetic acid. In most cases the acidity of the residue 

 was found to be chiefly composed of lactic acid. 



Proteids. — Coagulable proteids were obtained from the contents 

 of the lower ileum from the dog with a fistula on each occasion, 

 varying from 1*92 per cent, to a mere trace. JSTo relation could be 

 traced between the other factors and the quantity of coagulable 

 proteid present. 



On another occasion half-saturation of the contents with am- 

 monium sulphate, which precipitates globulins, brought down much 

 more than the half of the total coagulable proteid present, except 

 in the contents of the stomach. Albumoses were found in the 



