1889.] The Influence of Bile on the Digestion of Starch. 359 



a commercial pancreatin made from pig's pancreas, and ascertained 

 to be rich in the amylolytic ferment, have been used. 



Our earliest experiments indicated that bile had a very notable 

 influence on the pancreatic digestion of starch ; it caused a rapid dis- 

 appearance of the blue reaction of starch with iodine. 



Experiment A. Five tubes, a, &, c, d, e, each containing 50 o.c. of 

 the starch mixture (2 per cent.). With c 2'0 c.c. and with d and e 

 8*0 c.c. fresh pig's bile were thoroughly mixed. Equal quantities of 

 glycerine extract of pig's pancreas were then simultaneously added to 

 6, c, and d, and all five tubes were placed in a water-bath at 33 C. 

 The colour reaction of solution of iodine with the two control tubes 

 a which contained the starch mixture alone, and e which contained 

 the starch mixture and bile (8 c.c.) remained unaltered throughout 

 the experiment. The changed colour reaction in the other tubes 

 was watched by mixing a drop of the mixture with iodine solution on 

 a white porcelain plate. The blue reaction in d rapidly disappeared, 

 being replaced in less than one minute by a purple and in two 

 minutes by a red colour ; the red colour became gradually fainter and 

 had entirely disappeared in ten minutes. In b and c the blue reac- 

 tion disappeared more slowly, a purple colour being still obtained at 

 the end of ten minutes ; no difference was perceptible in this respect 

 between b and c, a fact which indicates that the amount of bile present 

 must exceed the proportion added to c before any accelerating in- 

 fluence wa.s noticeable. 



By using weighed quantities of the dried bile it was proved that a 

 larger proportion of bile caused the blue reaction with iodine to dis- 

 appear more rapidly than a small proportion. 



Experiment B. Four vessels, a, &, d, e, containing the starch 

 mixture 2 per cent. To b 0'6 per cent, dried pig's bile, to d and e 3 per 

 cent, dried pig's bile were added and dissolved ; to a, 6, and d equal 

 quantities of glycerine extract of pig's pancreas were added, and all 

 the vessels were placed in a water-bath at 33 C. ; d ceased to give any 

 colour reaction with iodine solution in five minutes ; at the same 

 moment the reaction given by b was reddish-purple, and by a purple ; 

 e remained unchanged. 



This increase of rapidity with increasing proportion of bile was 

 found to hold up to 4 per cent, of dried bile (equivalent probably to 

 at least 30 per cent, fresh bile). Beyond this percentage we have 

 not made experiments ; a larger proportion- of bile rendered the 

 mixture very thick and interfered with the colour reaction. 



It was also ascertained that the amount of sugar, estimated as 

 dextrose, formed under the conditions of Experiments A and B, was 

 greater when bile was present, and increased when the proportion of 

 bile was increased. 



Experiment C. Four vessels, a, 6, c, d, containing the -starch 



