SUMMARY AND CONCLUSIONS. 



195 



adherent to the walls of the beaker washed out, and the preparation made up to 50 c.c, 

 and then warmed in a water-bath to 37. To 5 c.c. of water was then added 0.75 gram of 

 pancreatin rubbed up to a paste in a mortar, and water gradually added to make 25 c.c, 

 and this preparation likewise placed in a water-bath warmed to 37. The starch and enzyme 

 preparations were then mixed antl jilaced in a moist chamber having a maintained tem- 

 perature of 37. At 15-minute intervals during the first hour the preparation was shaken, 

 and 5 c.c. removed, quickly boiled, and tested with a 2 per cent Lugol's solution and with 

 Purdy's solution. Two immediately subsequent observations were made at half-hour 

 intervals, and subsequently at 1-hour, and later at 2-hour intervals, the entire period of 

 actual experiment covering G hours. The record given in table 30 may be taken as 

 being practically absolutely identical with that of every starch, no matter what its source, 

 the de\'iations from this being absolutely insignificant, as shown by the sugar determina- 

 tions, which vary only in the third decimal figure. The sugar determinations were made 

 in terms of maltose. The pancreatin contained an appreciable amount of glucase, giving 

 rise to the conversion of some of the maltose into glucose, thus yielding higher values 

 than had the sugar consisted solely of maltose. 



Table 30. 



These results coupled with those of Ford, and of Ford and Guthrie, leave no doubt 

 that under the same conditions of experiment all boiled starches, from whatever source, 

 are practically absolutely identical in digestibility. 



SUMMARY AND CONCLUSIONS. 



Of the many methods and reagents used in the differentiation of different starches, 

 different grains of the same starch, and different parts of the same grain, it is obvious 

 that their relative values extend within very wide limits. Many of the results recorded are 

 fallacious, owing to the presence of foreign matter or of other incidental conditions; and 

 very frequently the reports of one observer are not confirmed, or are absolutely contra- 

 dicted, by those of others, even when the same method or reagent had been employed. 

 In many instances the cause of the different findings has been rendered quite obvious, 

 as in the discrepancies in the reports on the digestibility of boiled starches; but in others 

 it is not clear, as, for instance, in the repeated statements of the digestibility of raw starch 

 under conditions in which it is asserted bacterial action had been prevented. There will 

 be found, therefore, in the following paragraphs several statements ^^hich in the light of 

 these contradictions may be regarded as being tentative. The following statements cover 

 in a brief way the more essential points embraced in the literature referred to in this chapter : 



(1) That the histological method is of great value in the differentiation of starches 

 from different sources, different grains of the same starch, and different parts of the same 

 grain, but that this method of itself, if solely depended upon, to diagnose different kinds 



