Metabolism; Digestion and Translocation 275 



Inulin. - - Make and examine sections (mounted in alcohol) 

 from small pieces of the tuberous roots of Dahlia which have 

 lain for a week or 10 days in strong alcohol. Describe the 

 spherites observed. Treat the sections with cold water and ex- 

 amine, then treat with hot water, and discuss solubility. 



Glucose and other sugars. - The most decisive test for glucose, 

 other reducing sugars, and certain glucosides is the precipitation 

 of cuprous oxide in Fehling's solution. The identification of the 

 different sugars or other substances may require other tests. 



Prepare Fehling's solution using two bottles as follows: A, 

 34.6 grams of pure crystals of copper sulfate dissolved in distilled 

 water and made up to 500 cc. ; B, 173 grams of Rochelle salt 

 (potassium sodium tartrate) and 60 grams of sodium hydrate 

 dissolved in distilled water to make 500 cc. In employing this 

 test use always equal quantities of the two solutions. 



Add to some Fehling's solution in a test-tube a small granule 

 of glucose or a few drops of a strong solution. Boil the solution 

 for three minutes, and describe the reaction. In the same manner 

 test the juice of ripe grapes, or ripe plums or peaches. In this 

 case note the rapidity of the reaction, to contrast with a later 

 test of beet juice. 



Use the Fehling's solution with a few crystals of cane-sugar. 

 Is there any reduction ? Boil the cane-sugar previously with a 

 few drops of hydrochloric acid, neutralize with KOH (to litmus), 

 and then repeat the Fehling's test. Discuss. Press out some 

 juice of the sugar-beet, or grate up a small amount, and extract 

 with water ; then test this juice (or extract) with Fehling's 

 solution, being careful to heat gently, since violent heating will, 

 through other substances present, be alone sufficient to convert 

 cane-sugar. Compare the result with that obtained when grape 

 or peach is employed. Compare the reaction of crystals of cane- 

 sugar and granules of glucose in a few drops of concentrated 

 sulfuric acid. 



Celluloses. - - Crack a seed of date, make a section or shaving 

 of the endosperm, and study the preparation with respect to 

 the reserve cellulose deposited upon the cell-walls, describing 

 accurately the nature of the cells in which such deposits occur. 



