196 DIGESTION-MASTICATION, INSALIVATION, DEGLUTITION. 



passes after the precipitation of the organic matter, there is always a distinct, 

 red color on the addition of ferric sulphate. As this reaction is more marked 

 in the mixed saliva, the methods by which the presence of a sulphocyanide 

 is to be recognized will be considered in connection with that fluid. In the 

 human subject, the parotid secretion is more abundant than that of any other 

 of the salivary glands ; but the entire quantity in the twenty-four hours has 

 not been directly estimated. 



In the horse, ass and ox, it has been found that when mastication is per- 

 formed on one side of the mouth, the flow from the gland on that side is 

 greatly increased, exceeding by several times the quantity produced upon the 

 opposite side (Colin). This fact has been confirmed by Dalton in the human 

 subject. 



The flow of saliva from the parotid takes place with greatly increased 

 activity during the process of mastication. The orifioe of the parotid duct is 

 so situated that the fluid is poured directly upon the mass of food as it is un- 

 dergoing trituration by the teeth ; and as the secretion is more abundant on 

 the side on which mastication is going on, and the consistence of the fluid is 

 such as to enable it to mix readily with the food, the office of this gland 

 is supposed to be particularly connected with mastication. This is undoubt- 

 edly the fact ; although its flow is not absolutely confined to the period of 

 mastication, but continues in small quantity during the intervals. Its quan- 

 tity is regulated somewhat by the character of the food, being much greater 

 when the articles taken into the mouth are dry than when they contain con- 

 siderable moisture. In the human subject, the stimulus produced by sapid 

 substances will sometimes cause a great increase in the flow of the parotid 

 saliva. Mitscherlich and Eberle observed this in persons suffering from sali- 

 vary fistula and noted, farthermore, that the mere sight or odor of food pro- 

 duced the same effect. The supposition that the flow from the parotid is 

 dependent upon the mechanical pressure of the muscles or of the condyle of 

 the lower ja.w during mastication has no foundation in fact. In the horse 

 and in the dog, it has been observed that the secretion of the parotids is com- 

 pletely arrested during the deglutition of liquids, while the flow from the 

 other salivary glands is not affected (Bernard). 



The parotid saliva aside from any chemical action which it may have 

 upon the food, which will be fully considered in connection with the mixed 

 saliva evidently has an important mechanical office. It is discharged in 

 large quantity during the act of mastication and is poured into the mouth 

 in such a manner as to become of necessity thoroughly incorporated with the 

 food. Its use is chiefly, although not exclusively, connected with mastication 

 and indirectly, with deglutition; for it is only by becoming incorporated 

 with this saliva, that dry, pulverulent substances can be swallowed. 



Submaxillary Saliva. In the human subject, the submaxiliary is the sec- 

 ond of the salivary glands in point of size. Its minute structure is nearly 

 the same as that of the parotid. As its name implies, it is situated below the 

 inferior maxillary bone. It is in the anterior part of what is known as the 

 submaxillary triangle of the neck. Its excretory duct, the duct of Wharton, 



