THE SALIVA. 



The normal mixed saliva contains 



I. Inorganic 



II. Organic 



Carbonates ] [ magnesium. 

 Chlorids ! ! calcium. 

 Sulphates. [ | potassium. 

 Nitrites [ sodium. 



Sulphocyanate of potassium. 

 Albumin. 

 Mucin. 

 Ptyalin. 



Nitrites and sulphocyanates (sulphocyanids) are often 

 absent. The latter are most frequently found in the saliva 

 of smokers. The ptyalin has the power to convert boiled 

 starch into dextrin, maltose, and glucose. It is not able 

 to penetrate the granule of the unboiled starch, or does so 

 very slowly, differing in this respect from the correspond- 

 ing ferment of the pancreas. Its presence can be detected 

 by mixing the saliva with about ten times its volume of 

 a solution of boiled starc,h, keeping it awhile at body-tem- 

 perature, and after a few minutes testing for sugar. The 

 ptyalin acts best at about 40, and is, therefore, not the 

 same ferment as the diastase of malt, which decomposes 

 starch most rapidly at a temperature of 55. Ptyalin is 

 destroyed by acids, even as dilute as the 0.2-per-cent. hy- 

 drochloric acid of the gastric juice. It is, however, prob- 

 able that it acts for some time in the stomach before the 

 acid penetrates the mass of food in a large enough quan- 

 tity to stop the fermentation. 



The secretion is influenced by the nervous system. It 

 can be increased by mechanical means, like chewing a 

 pebble or a piece of rounded glass in the mouth; by 

 chemical action, such as touching the tongue with a crys- 



