Carbon Assimilation 
149 
Assimilation at High Temperatures . 
It is thus possible to construct a curve showing the relation 
between temperature and assimilation when neither light nor carbon 
dioxide supply is a limiting factor. Above 25"C, however, a fresh 
complication arises. Below 25 n C the amount of assimilation 
remains constant hour after hour, but above this temperature the 
rate of assimilation decreases with time. The initial rate of 
assimilation cannot be maintained. In all the experiments the rate 
of assimilation during the first li hours was not measured; 
measurements were then made of the assimilation taking place in 
successive hours. Finally the leaf was darkened and the respiration 
measured. The following tables show typical series of results for 
the assimilation of the leaf at a low temperature and at a high 
temperature during successive hours. 
Table XI. 
Assimilation of Leaf of Cherry Laurel at 8'8°C. 
Area of Leaf 44’6 sq. cms. 
Light Intensity. 
Time. 
Apparent 
Assimilation. 
Real Assimilation per 
50 sq. cms. per hour. 
Unit 
12.30-2.0 p.m. 
Preliminary 
Preliminary 
9 9 
2.0-4.0 ,, 
•00375 
•0023 
9 9 
4.0-6.0 „ 
•0037 
•00225 
Twofold 
8.0-9.40 „ 
Preliminary 
Preliminary 
99 
9.40-11.40 „ 
00665 
0039 
9 9 
11.40-1.40 a.m. 
•0066 
•0039 
9 9 
1.40-3.40 ,, 
•00645 
•0038 
1 J 
3.40-5.40 „ 
•0065 
•00385 
9 9 
5.40-7.40 ,, 
•0065 
•00385 
Table XII. 
Assimilation of Leaf of Cherry Laurel at 37‘5 n C. 
Area of Leaf, 36‘0 sq. cms. 
Respiration, 00019 grams per hour. 
Light Intensity. 
Time. 
Apparent 
Assimilation. 
Real Assimilation per 
50 sq. cms. per hour. 
45 
10.30 a.m.-12.0 noon 
Preliminary 
Preliminary 
9 9 
12.0 noon-1.0 p.m. 
•0154 
•0237 
9 9 
1.0-2.0 „ 
•0106 
•0176 
1 9 
2.0-3.0 
•00795 
•0139 
9 9 
3.0-4.0 „ 
•0059 
0109 
