THE CARBOHYDRATES OF THE ANGIOSPERM LEAF 21 



hexoses are usually more abundant than the sucrose, but 

 the change in the ratio from above downwards remains 

 much the same. This excess of hexoses in leaves not 

 brightly illuminated may perhaps be taken as support- 

 ing Strakosch's view that transformation of hexoses to 

 sucrose takes place only in light. As before pointed out, 

 the present writer is of the opinion that this conclusion is 



TABLE X. 



LEAVES OF SNOWDROPS GROWING IN OPEN ORDER. 



not justified by the experimental data, for the accumulation 

 of dextrose seems a more immediate cause of the conden- 

 sation to sucrose. 



THE RATIO OF SUCROSE TO HEXOSES. 



Another result of great interest was established by Parkin 

 namely, that the proportion of sucrose to hexose 

 decreases as the season advances. This Table XI. makes 

 very clear. The ratio recorded is calculated, taking the 

 amount of sucrose as unity. 



The ratios cannot be correlated with the daily tempera- 

 tures, and no very satisfactory explanation is forthcoming. 

 Girard's work on the beet leaf shows that in it hexoses are 

 always largely in excess of sucrose. His analyses were 

 made in August and September. 



