ORGANS OF THE BODY. 463 



246. 



The saliva, as found in the human mouth, is a very complex mixture 

 of the secretions of different organs connected with that cavity. In the 

 first place of the matters produced by the numerous little mucous glands 

 already described 244, then of those secreted by the parotid submaxillary 

 and sublingual glands. Under certain circumstances, also, the secretions 

 of the mucous membranes of the nose and lachrymal gland are likewise 

 mixed with it. We shall first enter upon the consideration of the variety 

 of composition of this fluid as a whole, and then turn to what has up to 

 the present been ascertained in regard to the individual secretions from a 

 physiological and chemical point of view. 



The saliva, taken as a whole, is a colourless, slightly clouded, and some- 

 what viscid fluid without either odour or taste. Its reaction is generally 

 alkaline or neutral, more rarely acid. Its sp. gr. ranges between T004 

 and 1-009. 



Under the microscope this fluid is found to contain cast-off epithelium, 

 and at times gland cells which have been washed out of their original 

 position. As a third and never absent element, we meet with great 

 numbers of what have been named salivary corpuscles (mucous corpuscles). 

 The latter present the same appearances as lymph cells which have 

 become swollen in water. Within their bodies, as long as they are 

 uninjured, a lively movement of small molecules may be perceived. This 

 motion was always regarded as of the ordinary molecular species, until 

 lately, when Briicke came forward to oppose the theory. 



Turning to the chemical analysis of the secretion, we find that it con- 

 tains between five and ten parts per 1000 of solid constituents. Among 

 the organic matters the most important is a ferment combined with alka- 

 lies or lime, called by Berzelius ptyalin insoluble in alcohol, slightly so 

 in water. It has not yet, however, been obtained in a pure state. 

 Besides this, leucin is probably present (?) also mucin, extractive matters, 

 fats, and combinations of the fatty acids with the alkalies. Urea has also 

 been found as an abnormal or pathological constituent. The inorganic 

 compounds are chlorides of the alkalies, small quantities of phosphates of 

 the alkalies and earths, carbonates, some oxide of iron, and besides, at 

 least in man, sulphocyanide of potassium (comp. 38). We insert here 

 an analysis by Frericlis, as a specimen of its quantitative composition. 

 The saliva of a healthy man contains : 



Water, 994-10 



Solid constituents, ..... 5 '90 



Epithelium and mucus. . . . . 2 '13 



Fat, . . 0-07 



Mucin and traces of alcoholic extract, . . 1'41 



Sulphocyanide of potassium, .... O'lO 

 Chloride of sodium, chloride of potassium, phos- \ 



phates of the alkalies, and earths, and oxide > 2 '19 

 of iron, ...... | 



The saliva contains of gases small quantities of nitrogen and oxygen 

 (the latter in far greater quantities than other secretions), and abundance 

 of carbonic acid. 



The amount of saliva secreted is, of course, liable to variation. Bidder 



