CHEMISTRY OF DIGESTION. 



LESSON VI. 



SALIVARY DIGESTION. 



1. To obtain mixed Saliva. Rinse out the mouth with water. 

 Inhale the vapour of ether, glacial acetic acid, or even cold air 

 through the niouth, which causes a reflex secretion of saliva. In 

 doing so, so curve the tongue and place its tip behind the incisor 

 teeth of the upper jaw. In a test-glass collect the saliva with as 

 few air-bubbles as possible. If it be turbid or contain much 

 froth, filter it through a small filter. 



2. I. Microscopic Examination. With a high power observe 

 e presence of (1) squamous epithelium, (2) salivary corpuscles, 

 ) perhaps debris of food, and (4) possibly air-bubbles. 



II. Physical and Chemical Characters. 



(a.) Observe its appearance either transparent or trans- 

 lucent and that when poured from one vessel to another it is 

 glairy and more or less sticky. On standing, a white deposit 

 is apt to form. 



(b.) Test its reaction, neutral or alkaline. 



(c.) Place a little mixed saliva in a test-tube, add dilute 

 acetic acid = a precipitate of mucin. Filter. 



(d). With the filtrate from (c.), test for traces of proteids 

 (albumin and globulin) with the xanthoproteic reaction 

 (Lesson I., 1, a), or by the addition of potassium ferrocyanide. 



(e.) To a few drops of saliva in a porcelain vessel, add a 

 few drops of dilute ferric chloride = a red coloration, due 



