66 THE SALIVA. 



161. PREPARATION OF KEPHYB. The preparation of the 

 ferment requires several days. First stir the kephyr-grains in a 

 little lukewarm water and decant the latter. Then cover them 

 with ten times their weight of milk which has been boiled and 

 cooled. Let them stand for twenty-four hours at about 20 C., 

 then pour off the milk, rinse the grains with a little water, and 

 repeat the digestion with milk for twenty-four hours as before. 

 This should be continued until the milk has an acid reaction and 

 the grains rise to the upper part of the liquid, which may require 

 five or six days. After this the grains may be allowed to stand 

 with a moderate quantity of milk, which becomes filled with the 

 organized ferment. At the end of twenty- four hours this is filtered 

 through muslin, and the filtrate added to ten or fifteen times its 

 volume of previously boiled and cooled milk. The whole is poured 

 into a clean strong bottle, the cork is tied in, and it is allowed to 

 stand two or three days at a temperature below 15 C., when the 

 fermentation is complete. The grains on the muslin can be used 

 an indefinite number of times in the same manner. 



162. Test the acid reaction of the kephyr by litmus-paper 

 (lactic acid) ; also show the presence of alcohol by the iodoform 

 test (Experiment 32). 



THE SALIVA. 



The saliva is a mixture of the secretions of the paro- 

 tid, submaxillary, and sublingual glands with that of the 

 glands of the membrane of the month. Its reaction is 

 normally faintly alkaline. The mixed saliva is a colorless, 

 more or less viscid liquid, often opalescent. On standing 

 it deposits calcium carbonate as a film on the surface. Ex- 

 amined microscopically it is seen to contain epithelial cells 

 from the membrane of the mouth, air-bubbles held by 

 viscid liquid, and salivary corpuscles which resemble the 

 lymph-corpuscles. Bacteria are abundant. 



