THE OXIDASES IN RELATION TO PIGMENTATION 283 



The green leaves of Rosa, Sorbus, and Mahonia, were 

 gathered on October 19, the red on October 29. In the 

 interval the occurrence of a sharp frost had induced the 

 formation of the pigment. 



From these figures it may be seen that the leaves in 

 which the red colour appeared were richer in sugars and 

 glucosides, but poorer in dextrins, than were the green. 

 In Ampelopsis, which was examined in August, the red 

 leaves, which were brightly illuminated, had a larger total 

 of carbohydrates than the green. In Spiraea the red leaves 

 on the ringed branches were of necessity richer in carbo- 

 hydrates than those on the untreated stems, which remained 

 green. The other deciduous plants, however, Rosa and 

 Sorbus, contained less carbohydrate in the red than in the 

 green leaves. The inferiority was due exclusively to the 

 insoluble types of carbohydrate, the soluble being some- 

 what more abundant in the red. Thus, before the fall of 

 the leaf a portion of the carbohydrate was translocated. 



These figures throw light upon the high osmotic pressures 

 found by Dixon and Atkins in leaves about to fall. The 

 carbohydrates are all mobilized, and diffuse or are con- 

 veyed from regions of high concentration in the leaf to 

 those of lower concentration in the petioles, branches, 

 main stem, and roots. In Mahonia, on the other hand, 

 the leaves are persistent, and the red contain more carbo- 

 hydrates, both soluble and insoluble, than do the green. 



Combes deduces from analyses that his anthocyanin 

 must be a glucoside, and points out that this is in agree- 

 ment with the researches of Von Portheim and Scholl(1908). 

 The work of Willstatter has, of course, now placed this 

 conclusion beyond doubt. Another view advanced by 

 Combes does not seem to be so certainly established, and, 

 indeed, he himself admits that there are many exceptions 

 to it. It is that, since there is an increase in the total 



