Carbon Assimilation. 
35 
Tropceolum wajus, September 11th, 1900. 
Leaves in sunlight under canvas screen. 
Duration of experiment 4-8 hours. 
Assimilation of C0 2 per sq. decimetre per hour ... 
Transpiration „ ,, „ 
Solar radiation incident on leaf per sq. cm. per min. 
Coefficient of absorption 
Solar radiation absorbed by the leaf 
Energy expended in assimilation 
,, ,, ,, transpiration ... 
Total Energy used for internal work 
Energy lost by re-radiation and convection 
1-210 c.c. 
0-1340 gm. 
0-1282 gm.-cal. 
0-700 
00897 gm.-cal. 
0-0010 „ 
0-0132 „ 
0-0142 „ 
0-0755 „ 
99 
99 
99 
99 
In the following table we give the summary of the energy 
relations as estimated by Brown and Escombe in five such experi¬ 
ments on Polygonum Weyrichii. 
Table XLIII. 
Mode of Disposal of Energy by the Leaf of Polygonum Weyrichii. 
Total Energy Received 100. 
Experiment. 
Energy 
used in 
Assimilation. 
Energy used 
in 
Transpiration. 
Total Energy 
expended in 
Internal work. 
Energy lost 
by 
Transmission. 
Energy lost by 
Re-radiation 
and Air 
Convection. 
1 
0-42 
9-67 
10 09 
35-31 
54-60 
2 
1-59 
53-60 
55-19 
35-30 
9-51 
3 
1-66 
57-01 
58-67 
35-32 
601 
4 
1-32 
35-64 
36-98 
35-28 
27-76 
5 
0-49 
52-72 
53-21 
35-30 
11-49 
In order to indicate the conditions of experiment, we give below 
(Table XLIV) the actual experimental data of these five experiments 
as recorded by Brown and Escombe. 
We do not intend to analyse in detail the results obtained by 
Brown and Escombe, as for reasons already given, we consider that 
at present it is not possible to obtain absolute values of the energy 
used in different processes. More light must be shed on the 
complexity and influence of the various factors before such 
numbers as Brown and Escombe’s can be discussed with profit. 
How much importance can be attached to such calculated 
values is indicated by the estimations of leaf temperature by Brown 
and Escombe. To obtain this they start with the assumption that 
