533 
Photosynthesis : a Reply to Criticism. 
represented by a rising curve of any kind, logarithmic or other, but simply 
by a straight horizontal line or indeed later a falling curve. Just as Brown 
and Heise, in the interests of their a priori theory, ignored the low tempera- 
ture results of Matthaei, so here, and for the same reason, they ignore the 
results of Pantanelli at the higher intensities of light. 
The Work of Reinke. 
Brown and Heise have used Expt. VIII of Reinke as the chief basis of 
the argument in which they attempt to obtain support for their theory 
from Reinke’s work. The curve of Expt. VIII, however, can be interpreted, 
with greater probability, as one which shows the action of two limiting 
Intensity of Light, i unit = intensity of sunlight. 
Fig. 2. Reinke’s results. Curve A. Average of all results in Tables I to VIII. B. Average of 
all results except those obtained after the plant had been once exposed to 16 units of light. 
Reading 60? with unit light in Expt. VI omitted from both curves. 
factors, first the light and later the C0 2 supply. But Expt. VIII does not 
show this so conclusively as do some of the other experiments, notably 
Expts. I, III, and VIII. In order to avoid all theoretical bias in the inter- 
pretation of Reinke’s experiments, Fig. 2, Curve A, has been drawn showing 
the average of all the experiments made by Reinke with his first arrangement 
of lighting, i.e. all the results shown in his Tables I to VIII. There can be no 
doubt that the curve obtained is one of the familiar type showing the action 
first of light as the limiting factor and later of C0 2 supply. Already at unit 
light the assimilation reaches its maximum and remains sensibly at that 
figure up to an intensity of l 6 times sunlight. 
Brown and Heise’s Table II gives the results for all Reinke’s experi- 
ments, and they say, ‘ These results are in agreement with the more detailed 
calculations given in Table I for Reinke’s Table VIII ’. As a matter of 
fact, the results in their Table II do not support their hypothesis. In 
Expts. I, III, and VII no increase is shown between unit sunlight and 16 
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