474 VICTOR C. MYERS 



80 mg., indicating that the high figures for potassium were due to post- 

 mortem causes and possessed no pathological significance. This post- 

 mortem increase is quite striking, however, since as high figures are 

 found one-half hour post mortem as at any other time. This very rapid 

 post-mortem rise in the potassium is significant. The findings for calcium 

 and magnesium differ little from those obtained in blood. Levinson(&) has 

 found that the pH determined immediately on withdrawing the fluid 

 varied between 7.4 and 7.6. It. was normal in all pathological conditions 

 observed, except epidemic meningitis, where figures of 7.3 to 7.4 were 

 generally observed. 



Saliva 



Mixed human saliva is composed of the secretion of three pairs of 

 glands, the submaxillary, sublingual and parotid, supplemented by the 

 secretion of numerous small glands called buccal glands. The saliva 

 secreted by the different pairs of glands possesses different characteristics, 

 the secretion of the parotid being thin and watery, while that of the 

 sublingual and submaxillary, particularly the former, is thick and viscid, 

 owing to the large amount of mucin present. The amount of saliva 

 secreted by an adult in twenty-four hours has been variously estimated 

 as between 1000 and 1500 c.c., the exact amount depending, among other 

 conditions, upon the character of the diet. The specific gravity varies 

 between 1.002 and 1.008, with an average of 1.005. 



According to Frerichs mixed saliva has the following composition : 



COMPOSITION OF HUMAN SALIVA 



formally saliva is alkaline to litmus and acid to phenolphthalein, the 

 reaction being practically the same as that of the blood. The chief con- 

 stituents of the ash are potassium, phosphate and chlorids, which together 

 constitute about 80 per cent of the mineral content. 



The important organic constituents of the saliva are the mucin (a 

 glycoprotein) and the salivary amylase, ptyalin, the former aiding in 

 swallowing and the latter in the digestion of starch. At one time it 

 was argued that ptyalin could be of little value in starch digestion since 

 it was probably destroyed by the hydrochloric acid of the gastric juice as 

 soon as it reached the stomach. It has been shown by Cannon, however, 



