348 Chittenden and Smith — Diastatie Action of Saliva. 



atnoiint of starch is converted into sugar in ;^0 minutes at 40° C. 

 Even with a dilution of 1 : 1000 or 2000, a recognizable amount 

 of sugar is formed under these conditions. This degree of dilution, 

 however, cannot l)e considered as being the limit at which diastatie 

 action will show itself, for with even greater dilutions, the starch is 

 converted into soluble modifications, colored blue by iodine, without 

 giving any recognizable amount of reducing substance; that is, 

 in ^th of the digestive mixture. Longer continued action at 40° 

 C. might yield some reducing substance ; it would seem, however, 

 from our experiments, that when a certain degree of dilution is 

 reached, the action of the small amount of ferment, in contact with 

 the larger amount of starch (1 gram) is devoted exclusively to con- 

 verting the granulose into soluble starch or other like body with non- 

 reducing action. This agrees with the results obtained by Griitz- 

 ner,* who found that the nature of the products obtained by the 

 action of ptyalin was dependent upon the intensity of the ferment 

 action ; with a small amount of ferment, erythrodextrin was the 

 main product, while with a large amount of ferment, sugar was 

 mainly formed. Diminishing the amount of starch in large dilutions 

 of the saliva tends, as might be expected, to increase the amount 

 of sugar formed. 



Comparison of the diastatie action of neutralized and normally 



alkaline saliva. 



Human mixed saliva, when freshly secreted, almost invariably pos 

 sesses a distinctly alkaline reaction. Some time ago one of us published 

 a series of experiraentsf on this point, in Avhich it was shown that the 

 average alkalinity of 51 samples of human mixed saliva, expressed as 

 sodium carbonate, was 0*080 per cent. The extreme variations of 

 alkalinity in the saliva from 14 individuals amounted to 0'085 per 

 cent, calculated as sodium carbonate (0"144-0"059 per cent). 



We have had occasion to make determinations of alkalinity in 15 

 additional samples of saliva, all collected by one person. We give 

 the results here, as affording additional data regarding the average 

 alkalinity of this secretion. The alkalinity is calculated, as hereto- 

 fore, in the form of sodium carl)onate,J The indicator used was deli- 

 cate litmus paper. 



* Pfliiger's Archiv der Physiologie, xii, p. 297. 

 ■\ Chittenden and Ely, Amer. Cliem. Jour., iv, 329. 



X Uudoiil)tedly tlio alkaline reaction of saliva is due in part to alkaline phosphates, 

 and probably the percentages given are only an approximation to the truth. 



