XV.J SALIVARY GLANDS AND PANCREAS, SALIVA. 161 



D. Saliva. 



1. Look at a little fresh saliva under tlie microscope 

 with a high power. Disregarding the flat epi- 

 thelial cells from the mucous membrane of the 

 mouth, note the salivary corpuscles; they are 

 larger than the ordinary white blood-corpuscles, 

 but in other respects closely i;esemble them. In 

 many, a very active Brownian movement of the 

 granules within the corpuscle may be observed. 



2. Test with neutral litmus paper the reaction of a 

 drop of saliva, it will be found to be alkaline. 



3. Induce the secretion of saliva by chewing a small 

 piece of india-rubber tubing, by filling the mouth 

 with ether vapour, or by rubbing the tongue 

 with a crystal of tartaric acid. 



If time allows let the saliva stand until the 

 turbidity has settled down into a sediment. To 

 a few c.c. of the fluid add strong acetic acid; 

 mucin will separate out as a stringy mass, 

 which does not dissolve in excess of acid. 

 Shake gently, or stir it with a glass rod the 

 mucin will form a clump, remove it, and if the 

 fluid is cloudy, filter. 



4. To the clear fluid add a drop or two of a strong 

 solution of potassium ferrocyanide. The slight 

 precipitate which results indicates the total 

 quantity of proteids present (cp. Lesson iil 

 § 16). If the reaction is not obvious, test 

 another small portion with Millon's reagent. 



l. 11 



