I 10 



THE CARBOHYDRATES 



In honey practically only invert sugar is found, although the 

 sugar found in the flowers by the bees is commonly cane sugar. 

 The hydrolytic agent in this case is most probably the formic 

 acid secreted by the bees. 



Cane sugar also has been recorded as occurring in Sphagnum, 

 Hypnum, and Pellia* The relative proportions of the three 

 sugars sucrose, levulose, and dextrose in certain plants have 

 been studied by Collins & Gill.f 



Thus in the case of Helianthus tuherosus, they found that 

 during the period August-December, the period of formation of 

 the tubers and thus of translocation, the total sugar of the 

 stalks reaches a maximum and then falls to a low value in 

 December. The amount of sucrose and levulose follows a 

 similar course, but the dextrose, which is in greatest abund- 

 ance in August, shows a sudden drop in September and then 

 increases, so that in December it is the chief sugar present, 

 being more than twice as abundant as either sucrose or 

 levulose. The accompanying table gives the actual figures 

 calculated to percentages of the living plant : — 



In the instance of oat straw, the preponderating sugar at 

 the end of vegetative activity is levulose not dextrose, which 

 suggests that the nature of the reserve material determines 

 the variety of the residual sugar. In the artichoke, the for- 

 mation of inulin means the fixation of levulose, wherefore 

 there will be a surplus of dextrose. In the oat, on the other 

 hand, dextrose is converted into starch so that there is a 

 residuum of levulose. In this argument Collins and Gill con- 

 clude that the hexoses have their origin in sucrose. In the 



* Goris and Vischniac : " Bull. Sci. Pharm.," 1913, 20, 390. 

 t Collins and Gill : "J. Soc. Chem. Ind.," 1926, 45, 63 T. 



