THE SALIVA. 209 



and which are probably nothing more than epithelial cells 

 in progress of development. 



The salts of human saliva are, according to Mitscherlich, 

 chloride of calcium, lactates of soda and potash, soda either 

 free or combined with mucus, phosphate of lime, and silica. 



In certain pathological states Simon detected in the saliva 

 acetic acid, and a considerable quantity of a substance re- 

 sembling casein. 



The saliva is with difficulty to be obtained in a pure state, 

 it being generally intermixed with a greater or less quantity 

 of buccal mucus; now the normal reaction of the saliva is 

 alkaline, that of mucus acid ; it therefore follows, the fluids 

 in question being thus intermingled in variable proportions, 

 that the reaction presented by the fluid obtained varies ac- 

 cording to the relative quantity of each ingredient; thus 

 sometimes the saliva, when tested, will appear to be acid, 

 alkaline, or neuter, and the same will be the case with the 

 buccal mucus. 



The true reaction of the saliva, then, can be ascertained 

 only by obtaining it unmixed with the mucus of the mouth, 

 and then testing it ; this may be effected by first washing 

 the mouth with water, and then applying the test paper to 

 the saliva as it flows from the orifice of its ducts. 



The fact referred to of the admixture of the two fluids, 

 saliva and mucus, will serve to explain why test paper ap- 

 plied to the upper surface of the tongue exhibits frequently 

 an acid reaction, while that placed beneath it manifests the 

 presence of an alkaline fluid. 



In morbid states the normal reaction of the saliva may 

 undergo a complete change, and it may become either neuter 

 or acid : this alteration has been especially observed to occur 

 in deranged conditions of the stomach, in acute rheuma- 

 tism, in cases of salivation, and, according to Donne, in 

 pleuritis, encephalitis, intermittent fevers, uterine affections, 

 and amenorrhea. 



Acid saliva doubtless exerts a very injurious effect upon 

 the teeth. 



The admixture of the saliva with mucus is readily shown 



s 2 



