MORBID SALIVA. 9 



thinks that it has the power of reducing fibrin to the condition 

 of a viscid fluid. 



[The services which the saliva performs in the animal eco- 

 nomy are classified by Dr. Wright as follow : 



Active. 1. To stimulate the stomach and excite it to acti- 

 vity by contact. 2. To aid the digestion of food by a specific 

 action upon the food itself. 3. To neutralize any undue acidity 

 in the stomach by supplying a proportionate alkali. 



Passive. 1. To assist the sense of taste. 2. To favour the 

 expression of the voice. 3. To clear the mucous membrane of 

 the mouth, and to moderate thirst. 



Mialhe 1 has recently announced the discovery of an active 

 principle in the saliva analogous in its physical and chemical 

 characters to diastase. It is solid, white or greyish-white, 

 amorphous, insoluble in alcohol, but soluble in water and spirit. 

 The directions for obtaining it are the following : Filter saliva 

 and treat it with five or six times its weight of absolute alcohol, 

 adding it as long as any precipitate occurs. This animal dias- 

 tase is insoluble, and falls in white flocks, which must be col- 

 lected on a filter and dried. It forms about '2g of the whole 

 saliva.] 



Leuchs 2 was the first who observed that saliva converts boiled 

 starch into sugar. 



Morbid Saliva. 



The saliva becomes affected in various morbid conditions of 

 the system, but the nature of the changes that it undergoes 

 has not hitherto been sufficiently studied. Morbid saliva 

 sometimes contains a free acid ; this is most commonly lactic 

 acid, but, in some cases, acetic acid is likewise present. The 

 acid reaction may be at once detected by test paper; while 

 normal saliva communicates a blue tint to red litmus paper, 

 this, on the contrary, reddens blue paper. I have frequently 

 seen the saliva acid in acute rheumatism, and in cases of sali- 



1 Lancette Fran?aise, 1845, April. 

 - Kastner's Archiv. 1831. 



