XII, c, 1 Broivn and Heise: Carbon Dioxide Assimilation 17 
Table 9 . — Comparison of experiments 56 and S7 of Matthaei. 
No. of experiment. 
Date. 
Tem- 
per- 
ature. 
Light 
inten- 
sity. 
Assimila- 
tion. 
37 
Mar. 4 
°c. 
11' 
8 
0. 0072 
5S 
Apr. 6 
1.5 
13 
0. 00705 
Matthaei uses a similar argument for a temperature of 23.7° 
(p. 80, par. 3) : 
The value of the assimilation is .0101 gramme per hour, less than the 
amount (.0128) induced in Experiment XXXVIII., Table VII., by one-third 
the light. Here again, therefore, there is no doubt that we are dealing 
with the maximal assimilation for 23°. 7 C. 
Experiment 57 was performed in April, and 38 in January, 
when the leaves are known to be much less active. If the latter 
experiment is plotted with Matthaei’s final curve, in which the 
former is used, the point for experiment 38 will be found to 
be considerably above the curve, showing that the argument 
for experiment 57 contains exactly the same fallacy as that 
for experiment 56. 
Matthaei’s reasoning in the case of a temperature of 30.5° 
is as follows (p. 80, par. 5) : 
To show that here the assimilation is maximal we must turn to the 
experiments in Table VIII. There the leaf chamber was in exactly the 
same position in the bath, the same burners were used, but were placed 
several millimeters further away. The value of the assimilation induced 
by this less intense light was, however, .0249 gramme per hour, showing 
that the light employed in the present experiment would have been 
sufficient to produce more assimilation than this, and therefore the value 
of .0136 gramme per hour must represent the maximal assimilation at this 
temperature. 
Here we have a comparison between experiments performed 
in April and in February. The fallacy is obvious from the dis- 
cussion of experiments 56 and 57. 
We have seen that Matthaei has failed to show that light was 
not a limiting factor in any of her experiments with temper- 
atures between 3° and 33.5°. We will now inquire into the 
effect of light in these experiments. In fig. 3 all of the assimi- 
lation values obtained with temperatures within the above 
limits, in Tables 6 and 8, are plotted with reference to light 
intensity. These tables contain all of the numbers used by 
Matthaei in plotting this part of her final curve. In fig. 3 they 
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