294 Tlie i'drholiijdnttoi of the Maiujuld Leaf 



to and even nearly double the saccharose ( -^ = 0-94-1-60 in September, 



\c.s. 



and 1-M to 1-9:5 in OctoberV 



An exactly similar increase in the proportion of reducing sugars was 

 observed by Parkin [1912] in the case of the snowdrop (Galanthus nivalis). 



1. Whereas in the first stage of growth practically all the reducing 

 sugar and about one-half of the cane sugar are used up in the night, 

 in the later stages of growth only a small part of these sugars disappears 

 in the night, so that each day's activity commences with a larger pro- 

 portion of total sugars. This is well seen from the following data: 



% hexoses % saccharose 

 At sunrise, August 27th 0-20 1-50 



September nth 6-30 4-24 



„ October 12th 9-62 4-98 



The store of reducing sugars which is thus available at the com- 

 mencement of the day steadily and rapidly grows, especially in the earlier 

 part of the season ; but the store of cane sugar in the leaf, although 

 increasing rapidly from August 27th to September 11th seems to reach 

 a nearly stationary value. Table IV shows that the limils between 

 which the sugars vary constantly rise during the season, but not so much 

 in the case of the cane sugar as in that of the reducing sugars ; but the 

 range of variation for the 24 hours increases considerably more in the 

 case of the saccharose than in that of the hexoses. It must be noted, 

 however, that the range of variation during the daylight period, up to 

 the time of reaching the first maximum (which corresponds with the 

 temperature maximum), is always greater in the case of the hexoses 

 than the saccharose, and especially so in the first two series; when 

 growth of the root is nearly complete, the range of variation of the 

 cane sugar in the leaf during the period of illumination becomes far 

 greater. In this case, when the root has nearly reached the limit of its 

 storing capacity, the leaf itself seems to act as a temporary reservoir 

 of cane sugar. This is shown bv the followinir data : 



