

1889.] The Influence of Bile on the Digestion of Starch. 361 



as dextrose by Fehling's method, but we are unacquainted with any 

 reagent which will effect the separation of dextrin from starch ; they 

 can both, however, be precipitated by absolute alcohol. We have 

 made a quantitative estimation of the relative amounts of starch, 

 dextrin, and sugar by the following method : two equal portions of 

 the starch mixture, 2 per cent., were digested with equal quantities 

 of dried pig's pancreatin,* rich in amylopsin, a certain proportion of 

 bile salts (made from pig's bile) having been previously added to one. 

 Digestion was allowed to proceed in the incubator until the reaction of 

 starch with a solution of iodine had completely, or almost completely 

 disappeared from the vessel to which bile salts had been added. Both 

 mixtures were then rapidly boiled to stop the action. The digested 

 mixture was then poured into a dialyser (made of German sausage 

 paper) and dialysed in running water for four or five days, thymol 

 being added to prevent decomposition (which did not occur) ; the 

 dextrin, sugar, and most of the salts were thus dialysed away, and 

 the total residue (starch) was estimated by evaporating the dialysed 

 liquid to small bulk and filtering into alcohol. The precipitate was 

 caught on a filter, dried at 100 to 110 C., and weighed. The residue 

 of undigested starch was thus estimated. The proportional amounts 

 of sugar and dextrin were estimated by dialysing the liquids di- 

 gested under the same conditions as those just described, in distilled 

 water for four days, decomposition being prevented by the daily ad- 

 dition of thymol. Equal quantities of the two dialysates, the one 

 containing sugar and dextrin, the other sugar, dextrin, and bile 

 salts, were evaporated to small bulk, the sugar estimated as dextrose 

 by Fehling's solution, the dextrin by precipitating a measured 

 quantity of each concentrated liquid by absolute alcohol, washing 

 with absolute alcohol to remove bile salts, drying at 100 to 110C., 

 and weighing. 



The results are shown in the following experiments : 

 Experiment D. To one of two flasks containing 200 c.c. of the 

 starch mixture (2 per cent.) 0'6 per cent, bile salts was added ; 0'8 per 

 cent, pancreatin was then added to both flasks and the mixture digested 

 at 38 C. for two minutes. The flask containing bile salts then gave 

 no reaction with iodine solution, while that which contained pan- 

 creatin alone gave a purple reaction. Both fluids were then dialysed 

 in cold distilled water for four days, decomposition being prevented by 

 the daily addition of thymol. Both dialysates, which were faintly acid 

 and contained no starch, were then evaporated to small bulk, and 

 each divided into two parts for the estimation of sugar and dextrin 

 respectively. The former was estimated as dextrose by Fehling's 

 process, the latter by precipitating under absolute alcohol, filtering, 

 drying at 100 110 C., and weighing. The result was : 

 * Prepared by Messrs. Savory and Moore. 



