14 
The Philippine Journal of Science 
1917 
two to four units, or 100 per cent, increased the assimilation 
24 per cent ; raising the light from four to six units, or 50 per 
cent, increased the assimilation 8.6 per cent. This certainly 
shows that at 11°, four units is not the maximum amount of light 
that the leaf could use in assimilation. Nor is there any proof 
that the maximum was attained with six units of light, for 
throughout Matthaei’s experiments there is for each increase in 
light intensity a rise in assimilation ; but this is, per unit of light, 
progressively smaller. 
In Matthaei’s curve the difference in the results obtained by 
increasing the light from two to four units at 11°, over those 
caused by a rise from four to six units, is exaggerated by a mis- 
placement of the points for these figures. 
In view of the fact that four units of light are certainly not the 
maximum that the plant can use at 11.4°, it seems hardly reason- 
able to suppose that two units could have been at 9°, as is assumed 
to be the case by Matthaei on the basis of her apparently unreli- 
able figures for four units. 
The figures which we have just discussed for 9° and 11.4° are 
used by Matthaei for the lower temperatures above 0.0° in con- 
structing her final curve. Before considering the figures for the 
higher temperatures, we will take up the results with light 
intensity of eight units. These are given in Table VII of the 
original publication, and are summarized in Table 7 of the present 
paper. 
Table 7. — ‘^Assimilation experiments at medium and high temperatures 
with light of eightfold intensity (L. In. =8). Two ordinary incandes- 
cent burners at low gas pressure.” (Matthaei, Table VII.) 
Experiment No. 
Date. 
Temper- 
ature. 
Assimila- 
tion per 
hour per 50 
sq. cms. 
1903. 
=c. 
Grains. 
XXXVB - _ - 
Mar. 4 
11.0, 
0. 0072 
XXXVIII. 
Jan. 29 and 30 
25.4 
0.0128 
XXXIX 
25.3 
0. 0125 
XL - - — - 
Feb. 4 
32.1 
0. 01295 
XLI - — 
Feb. 5 
32.2 
0.0130 
XLII , - 
Feb. 2 
38.3 
0.0115 
XLIO 
Feb. 3 
38.3 
0. 0130 
XLIV - 
Feb. 9 
40.9 
0.0078 
XLV . 
Feb. 10 
40.9 
0. 0080 
XLVI . . - - 
42.9 
0.0040 
XLVII 
Feb. 7 . 
42.9 
0.00355 
