Carbon Assimilation. 
217 
E. Variations in the Carbohydrate Content of Leaves. 
1. Garden Nasturtium (Tropceolum majus) (Brown and Morris). 
•f 
Tropceolum majus possesses a leaf which forms much starch. 
Brown and Morris analysed three sets of leaves of Tropceolum majus 
by their methods indicated in the last section. One set of leaves 
was picked at 5 a.m. and quickly dried in the steam oven; the 
second set was picked at the same time and kept in sunshine for 
12 hours with the petioles in water before drying; the third set 
was picked at 5 p.m. after 12 hours insolation. The results of the 
analysis are given in the following table. 
Table XXX. 
Variation in Starch and Sugar Content o/Tropoeolum Leaves , 
August 23rd. 
The values are given in percentages of the dry weight. 
Carbohydrate. 
Picked and dried 
5 a.m. 
Picked 5 a.m. 
Kept insolated in 
water until 5 p.m. 
Picked and dried 
5 p.m. 
Starch . 
1-23 
3-91 
4-59 
Sucrose. 
4-65 
885 
3-86 
Glucose . 
0-97 
1-20 
000 
Fructose 
2-99 
644 
039 
Maltose ... 
1*18 
0-69 
533 
Total Sugars ... 
9-69« 
17T8 
9-58 
In a further experiment one set of leaves was picked and dried 
at once while another set was placed in water in the dark for 24 
hours after picking. The results of the carbohydrate analysis were 
as follows:— 
Table XXXI. 
Carbohydrate Content of Leaves before and after 24 hours in the 
Dark. 
Carbohydrate. 
Leaves picked and 
dried at once. 
Leaves kept in the dark for 
24 hours after picking. 
Starch ... 
3-693 
2-980 
Sucrose ... . 
9-98 
3-49 
Glucose . 
o-oo 
0-58 
Fructose . 
1-41 
3-46 
Maltose. 
2-25 
1-86 
Total Sugars. 
13-64 
9-39 
. 1 • .... 
1 This is the number given by Brown and Morris. 
