COMPOSITION OF SALIVA. 



THE CHARACTERS OF MIXED SALIVA. 



129 



FIG. 63. 



The liquid in the mouth is a mixture of the secretion of the 

 salivary glands as well as of the small purely mucous glands. 



It is a slightly turbid tasteless fluid of a distinctly alkaline 

 reaction, of 1004-1008 specific gravity, and so tenacious that it 

 can be drawn into threads. The amount secreted by an adult 

 human being during twenty-four hours varies greatly according 

 to circumstances, and has been variously estimated by different 

 authors, by whom the wide limits of 200-2000 grms. (7-70 oz.) 

 have been assigned as the daily amount. 



The saliva contains about 5 per cent, of solids. Of these the 

 greater part are organic, namely : (1.) Mucin, from the submax- 

 illary, sublingual, and small mucous glands, which can be pre- 

 cipitated by acetic acid. To this 

 substance the viscidity of the 

 saliva is due. (2.) Traces of al- 

 bumin precipitable by concen- 

 trated nitric acid and boiling 

 (3.) Traces of globulin, precipi- 

 tated by carbonic acid. (4.) Pty- 

 alin, a peculiar ferment. 



The inorganic constituents are 

 salts, among which an inconstant 

 amount of potassium sulpho-cya- 

 nate is found, a substance which 

 does not exist in the blood. 



There are also many morpho- several (6) bacteria, and (i) mi- 

 logical elements : of these the ma- crococci. 

 jority are accidental, being the re- 

 mains of food, etc. ; others are more or less characteristic, namely : 

 (1.) Salivary corpuscles which are rounded protoplasmic masses 

 containing nuclei and coarse granules which show Browniau 

 movements. (2.) Epithelial scales from the surface of the mu- 

 cous membrane of the mouth. (3.) Various forms of protophyta, 

 which propagate readily amid the decaying particles of food in 



11 



The form elements from mixed 

 saliva from tip of tongue, showing 

 (e) large irregular scaly epithelial 

 cells, (c) round salivary corpuscles, 



