8 CHAPTER XXII. 



DIGESTION. 



Saliva. See starch. Collect saliva as already directed,, 

 pg. 124. 



1. To saliva add 2 volumes water, then a few drops of 



acetic acid. A white stringy pp of mucin falls. 



2. To saliva add a drop of ferric chloride solution. A red 



colour results, which is discharged by HgCl 2 Potassium 

 sulpho-cyanide. 



Gastric Digestion. 



Arrange the following digestions at 40 C. in the water-bath,, 

 in tubes : examine 30 minutes afterwards : 



1. Water + a small flocculus of Fibrin. No change. 



2. A 0-2 p - c - solution HC1. + Fibrin. The fibrin swells. 



3. Water + a, little Pepsin (Extract) 1 + Fibrin. No effect. 



4. Dilute HCI + Pepsin + Fibrin. The fibrin is dissolved. 



Whilst waiting, proceed with the following : 



Products of Gastric Digestion. 



Fill a beaker one-third full of the fibrin which is provided 

 for you and which has been swollen in 0'2 p>c - HC1, to it add 

 another volume of dilute acid and raise the mixture and 

 maintain it at 40 C., then stir in 5 CC peptic extract (Benger's). 

 In a few minutes the gelatinous mass will become fluid. 

 Strain through filter paper to remove coarse impurities, and 

 return it to the beaker and continue the digestion. 



i Neutralised Liqueur pepticus (Benger) or a glycerin extract. 



