W. A. Davis and G. C. Saw\t:r 373 



variation of the sugars (1-93 per cent.) is however far less than in the 

 mangold (4-68). The last two columns show how greatly the proportion 

 of sugars and substances soluble in alcohol increases in the mangold 

 in the later stages of growth. 



Table III. 



Range of Variation of Sugars and Alcohol-soluble Matter in 

 the Mangold and Potato. 



Table III shows that in both mangold and potato leaves the daily 

 fluctuation of the substances soluble in alcohol is always far greater than 

 (often nearly double) that of the total sugars. The same is true of the 

 potato stalk, but in the mangold stalk the change in the sugars is always 

 much greater than that of the alcohol-soluble constituents. 



C. The Dextrose-Laevulose Ratio. 



The ''apparent" dextrose and laevulose have been calculated, as 

 in the case of the mangold, on the assumption that the pentoses are 

 either arabinose or xylose. The values are given in Tables IV and V. 



D = percentage of apparent dextrose calculated on the total vacuum- 

 dried matter (t.v.d.m.). 



L = percentage of apparent laevulose calculated on the total vacuum- 

 dried matter (t.v.d.m.). 



I. Leaves. 



As was the case in Series I of the mangold pickings (Paper II, p. 3-35) 

 the results obtained for the "apparent "dextrose and laevulose are of little 

 real value as an index of the true proportions of these sugars present, 

 owing to the presence of optically active impurities which cannot be 



