LABORATORY MANUAL OF PHYSIOLOGY. 



(e) To another portion of the test solution add lactose. Is the 

 copper salt reduced ? 



(/) Test a solution of cane sugar for reduction. Result ? 



(g) Partly fill three test-tubes with starch paste. Mark them 

 I, II, and III. To I add some of the filtered saliva. To II add 

 some saliva that has been heated to boiling. To III add some 

 saliva that has been neutralized with HC1 and has had enough 

 acid added to bring the acidity up to i per cent HC1. Place the 

 three tubes in a water-bath or in the incubator kept at a tempera- 

 ture of 38 C. In five minutes remove the tubes and test the 

 three for reducing sugar with Fehling's solution. Is there any 

 reducing sugar in I ? in II ? in HI ? Explain. 



(//) Make a solution of dextrin. To this solution add a few 

 drops of iodine. Note the wine-color reaction. 



(t) To a few cubic centimetres of the dextrin solution add an 

 equal quantity of saliva. Place in the water-bath or incubator for 

 one hour at a temperature of 38 C. At the end of this time test the 

 solution with iodine for the red dextrin reaction. Is there any 

 color reaction? Test for reducing sugar. 



(f) Mix equal quantities of boiled starch and saliva in a test- 

 tube. Place in the warm water-bath. Place several drops of dilute 

 iodine solution on a white porcelain slab. At five-minute intervals, 

 by means of a glass stirring-rod, add a drop of the digesting starch 

 to a drop of the iodine on the slab. Continue this until a color re- 

 action is no longer obtained. \Yhat changes occur in the color 

 reaction as digestion progresses ? 



(k) Take some boiled starch into the mouth and go through the 

 movements of mastication. At the end of one minute spit this out 

 into some boiling water in a beaker. Test a portion of the mixture 

 for sugar, and another portion for starch . Repeat with another por- 

 tion of starch, keeping it in the mouth two minutes. Chew another 

 portion for five minutes and test again for starch and sugar. Does 

 the lest for starch diminish in intensity, and the test for sugar 

 increase ? 



(/) Mix a portion of fibrin in a test-tube with some saliva. 



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