368 Chittenden and Smith — Diastatic Acfioji of Saliva. 



ularly retarding the action of the ferment ; thus, as Langley and 

 Eves state, " O-OOVS per cent, hydrochloric acid may be added to 

 saliva diluted 10 or 20 times, provided 1 per cent, peptone be present, 

 and yet its action on starch be about equal to that of the saliva 

 without peptone or acid." 



Again it would appear that small percentages of acid-proteid mat- 

 ter, either peptones or the albuminous bodies present in saliva, tend 

 to increase the diastatic action not only beyond the natural action 

 of the saliva, but also somewhat beyond the action of the saliva plus 

 the same percentage of neutral peptone. Thus, while the presence 

 of a few hundredths of 1 per cent, of neutral peptone in saliva 

 diluted 1 : 50 caused about 1 'o per cent, increased conversion of 

 starch, acid-peptone caused in 30 minutes 2"17 per cent, increased 

 conversion. Again, as has been seen, the acid-proteids of saliva 

 cause a like increase. Large percentages of acid-proteids, however, 

 in which the albuminous matter is completely saturated,' distinctly 

 retard the diastatic action. 



These results harmonize in a general way with the previous results 

 obtained by one of us,* in which it was found that the presence of 

 1 per cent, peptone in an acid-reacting fluid, which by itself almost 

 completely stopped the diastatic action of the saliva, increased 

 the diastatic action of the ferment above the action of the neutral 

 saliva and also above the action of the neutral saliva plus the 1 per 

 cent, of neutral peptone. 



We next endeavored to ascertain how ranch of tlie retarding 



action of the acid-peptone is due to destruction of the ferment. 



Without giving details we have found that with saliva ten times 



diluted there is a noticeable destruction of the ferment in the presence 



of 0-028 per cent, of combined acid, although it is not great. In 



this case it is to be understood that the amount of peptone present 



is only such as would furnish this percentage of combined acid. 



The following percentages of starch converted (after neutralization 



and equalization) show the amount of destruction under the difl'erent 



conditions. 



Series XIX. 



* Chittenden and Ely, loc. cit. 



