THE MIXED SALIVA, THE SECRETION OF THE MOUTH. 263 



hydriodic acid when added to saliva, with the development of a yellow color, and 

 the formation of iodin, which can be recognized by the addition of starch. 

 It is absent when the flow of bile into the intestine is prevented. It is formed 

 through proteid metabolism, perhaps from the contained cyanogen. As potassium 

 sulphocyanid is toxic for plants and microorganisms, it may be concluded that 

 it acts, within certain limits, as a disinfectant for the buccal cavity. 



The inorganic elements in the saliva are mainly potassium and sodium chlorids, 

 with calcium bicarbonate, and calcium and sodium sulphates, phosphates, and 

 chlorates. 



The submaxillary saliva is alkaline, sometimes strongly alkaline. 

 On standing for some time it precipitates fine crystals of calcium car- 

 bonate, together with an amorphous, albuminoid substance. It always 

 contains mucin, and it is, therefore, as a rule somewhat ropy; also 

 ptyalin less than in the parotid secretion; and only 0.0037 P er cent, 

 potassium sulphocyanid. 



In the submaxillary saliva of the dog there were found 1.755 of organic matter, 

 of which 0.662 was mucin; from 2.604 to 3.662 of inorganic salts; and from 0.263 

 to 1.123 f soluble salts. 



Pfliiger investigated the gases of the submaxillary saliva and found, in 100 

 cu. cm. of saliva, 0.6 of oxygen, 64.7 of carbon dioxid, partly removable by exposure 

 to a vacuum and in part capable of being expelled by phosphoric acid; and 0.8 of 

 nitrogen; or of gases in 100 volumes 0.91 of oxygen, 97.88 of carbon dioxid, and 

 i. 2 1 of nitrogen. Kiilz found in human parotid saliva as much as 1.46 volumes 

 per cent, of oxygen and 3.2 of nitrogen, 4.7 of carbon dioxid removable by 

 suction, and 62 of combined carbon dioxid. 



The sublingual saliva, more viscous and more coherent than the 

 submaxillary saliva, is strongly alkaline in reaction. It contains much 

 mucin, numerous salivary corpuscles and some potassium sulphocyanid; 

 but its composition has, on the whole, not been determined accurately. 



THE MIXED SALIVA, THE SECRETION OF THE MOUTH. 



The buccal fluid is a mixture of the secretions of the salivary glands 

 and the small glands of the mouth. 



Physical Properties. It is an opalescent, tasteless and odorless, 

 somewhat ropy fluid, with a specific gravity of from 1002 to 1006, and 

 an alkaline reaction, due to alkaline phosphates. 



Between midnight and morning the reaction may be faintly acid. The decom- 

 position of epithelium, of salivary corpuscles or of remains of food by microbes may 

 also cause the reaction to be acid temporarily, particularly after long fasting and 

 after much talking. In the presence of digestive disturbances and of fever the 

 reaction is not rarely acid, in consequence of stagnation and insufficient secretion; 

 therefore, also, the mouth is dry. 



The amount in twenty-four hours is between 200 and 1500 grams, 

 according to Bidder and Schmidt between 1000 and 2000 grams. The 

 total solids in the secretion amount to 5.8 per cent. 



The solids are : 2.2 of epithelium and mucus, 1.4 of ptyalin and albumin, 2.2 

 of salts and 0.04 per cent, of potassium sulphocyanid in 1000. 

 especially potassium, phosphoric acid and chlorin. 



Microscopical Constituents. (a) The salivary corpuscles, from 8 to n // m size, 

 are nucleated, protoplasmic, spherical cells, without a limiting membrane 

 exhibit as a vital phenomenon so-called molecular movements on the part of then 

 numerous dark granules, which are embedded in the protoplasm, through whose 

 internal flowing movement they are set into a tremulous, dancing locomotion, 

 which ceases with the death of the cells. Salivary corpuscles can be easily brought 

 into view by slight pressure upon the excretory ducts beneath the tongue. 



