360 Chittenden and Smith — Diastatie Action of Saliva. 



decided influence on the diastatie action of saliva in acid solutions ; 

 that while the presence of 0*025 per cent, hydrochloric acid pre- 

 vented the conversion of but 3-50 per cent, of the starch into 

 sugar, the presence of 1 per cent, peptone allowed the conver- 

 sion of 48-85 per cent, of the starch, 7 per cent, more than the saliva 

 alone would convert under like conditions; a fact which would 

 indicate something more on the part of the proteid matter, than a 

 mere union of the peptone and acid. Undoubtedly there was a 

 combination of the peptone and acid, but in addition there was man- 

 ifested the direct stimulating action of the proteid matter. At the 

 time these experiments were made, however, we were unaware of 

 Danilewsky's* method of testing for free acid with troj^aeolin 00, by 

 which he proved the union of acids with various forms of proteid 

 matter ; compounds acid to test papers, but not containing free acid- 

 Falkf likewise noticed the influence of peptones on diastatie action, 

 in an acid solution of malt infusion ; thus by adding a small amount 

 of 00135 per cent, hydrochloric acid to an infusion of malt and this 

 to some starch paste, no reaction for sugar could be obtained, but by 

 adding the same proportion of acid and some peptone, then the sugar 

 reaction soon appeared. This fact Falk considered as evidence of 

 the union of the acid and peptone. 



In view of these results we have repeated some of our previouK 

 work, under diflerent conditions, trying many additional experi- 

 ments, especially as in a recent paper on the araylolytic action of 

 saliva, Langley and EvesJ have arrived at some conclusions not in 

 accord with our results. 



a. Infiuence of acid-proteid matter. 



We have used the tropa?olin test for the detection of free acid, 

 whenever it has been necessary in our work, employing the method 

 as recommended by Danilewsky. The tropa?olin 00 was dissolvod 

 in methyl alcohol (saturated solution) and when a test for free acid 

 was to be made, drops of the alcoholic solution were allowed to 

 evaporate on a porcelain plate at 40° C, and then while still at 4u° C, 

 a drop of the fluid to be tested was added and allowed to dry. Free 

 hydrochloric acid causes the dry residue to take on a violet color. 

 We have made a number of trials to ascertain hoAV small a percent- 

 age of free hydrochloric acid can be detected by this test. Using a 



* Centralbl. Med. Wiss., 1880. 



f Virchow's Ardiivs, Ixxxiv, 1881, p. i:!(). \ Loc. oit. 



