1 1; 



Carbon Assimilation. 



As the season advances, the hexose sugars in the leaf increase 

 in proportion to the sucrose, as the following table shows. 



Table XXXIV. 



Sensoiml Variation of Sugars in Snowdrop Leaves. 



Parkin considers that his results strongly support Brown and 

 Morris' view that sucrose is the first recognisable sugar to appear 

 in the leaf, and that glucose and fructose arise from it by inversion. 

 He also brings forward evidence in support of Brown and iVIorris' 

 contention that fructose is generally present in excess of glucose. 

 Thus, out of 54 analyses, in 47 cases fructose was in excess of 



glucose, the proportion — varying from to -- , while 



glucose 0-4 0-76 



in only 7 cases was the reverse the case and then the glucose was 



only slightly in excess, the fructose : glucose ratio varying from 



1 : I'Ol to 1 : 1'06. As there is a {greater tendency for the fructose 



to be destroyed by the careless use of basic lead acetate, these 



7 results are probably due to experimental error. Parkin considers 



therefore with Brown and Morris, that glucose contributes more 



readily than fructose to the needs of the leaf. 



3. Mangold (Beta vulgaris, L., var. Sutton's Yellow Globe). 



Davis, Daish and Sawyer have attempted to obtain information 

 in regard to the sugars in leaves and leaf stalks of the mangold at 

 different times of the day and night and at different seasons by an 

 extensive series of analyses carried out at Rothamsted. 



Collections of leaves were made from plants growing in the 

 field at 2-hourly intervals over a 24 hour period. Such series of 

 measurements were made at three different times. 



I. Stage of early growth. 6 a.m., August 26—4 a.m., August 

 27, 1913. 



