Chittenden and Smith — Diastatic Action of Saliva. 349 



Average alkalinity of the 15 samples, 0-097 per cent. 



It was demonstrated some time ago by one of us* that neutralized 

 saliva had as great a diastatic power as the unneutralized or normally 

 alkaline. In fact, the single result which we recorded plainly indi- 

 cated a greater diastatic power on the part of the neutralized saliva, 

 since from the digestion with normally alkaline saliva, one-tenth of 

 the mi.vture gave 0905 gram" metallic copper, while the same quan- 

 tity of the saliva neutralized, gave under like conditions 0-0943 gram 

 copper; thus showing that the alkaline saliva had converted 41-58 

 per cent, of the starch into sugar, while the same quantity neutral- 

 ized had changed 43*28 per cent. In these two experiments, how- 

 ever, the amount of saliva used was large, being one-fourth of the 

 entire digestive mixture, viz., 25 c.c. 



Recently Langley and Evesf have made the statement that " neu- 

 tralized saliva converts starch into sugar much more actively than 

 unneutralized saliva," without, however, giving any data. These are 

 the only two statements recorded bearing on the relative diastatic 

 action of the neutralized and normally alkaline secretion. 



Our experiments, however, show that there is a very great difier- 

 ence in the action of ptyalin in neutralized and unneutralized saliva; 

 a difference which is more manifest when the saliva is greatly diluted 

 and seemingly out of all proportion to the amount of alkali present, in 

 cases where the dilution is 1: 100 or more. The following experi- 

 ments show the amount of difference. 



* Chittenden and K\y. Amer. Cliem. .Jour., iv, 112. 



f On certain conditions which influence the amyloU'lic action of saliva. Journal 

 of Pliysiology, vol. iv, No. 1. 



