26 SOME RECENT RESEARCHES IN PLANT PHYSIOLOGY 



It may be seen that the accumulation of sucrose owing 

 to prevention of translocation is considerable, and that 

 the hexose has fallen somewhat. 



Another important conclusion reached by Parkin is that 

 as a rule ^-fructose is in excess of glucose in the leaf of 

 Galanthus. Thus, out of fifty-two duplicate analyses the 

 fructose and glucose were present respectively in the ratio 

 of from 1:0-4 to 1 : 0-76 in forty-seven, whilst in the 

 remaining five the ratio was from 1 : 1*01 to 1 : 1*06. 

 From the details of the separate estimation of each hexose, 

 which he did not publish, he concludes that the proportion 

 of fructose to glucose tends to rise during the night, when 

 naturally photosynthesis is in abeyance, and also to increase 

 from above downwards in the leaf, being especially large in 

 the colourless basal portion. This excess of fructose over 

 glucose agrees with the results of Brown and Morris obtained 

 with Tropseolum. These authors consider that glucose is 

 more readily respired than is fructose. That glucose should 

 be less plentiful than fructose is hard to account for, 

 according to the views of Strakosch, though on the assump- 

 tion made by Brown and Morris, that sucrose gives rise to 

 both by inversion, and that glucose is used up more readily, 

 the experimental results are easily explicable. Presumably 

 the excess of fructose goes to form the inulin which is stored 

 in the bulb. On the other hand, the increase in the pro- 

 portion of fructose from above downwards is quite in 

 accordance with the work of Strakosch, as this change is 

 supposed to take place in the veins. 



THE EFFECTS OF PROLONGED DARKNESS UPON THE 

 CARBOHYDRATES OF LEAVES. 



Further experiments showed that prolonged darkening 

 of the leaves never results in anything approaching complete 

 exhaustion of the sugars, as the supply is evidently made 



