8 The Philippine Journal of Science 1917 
usually based on these figures. Kanitz** holds that Matthaei’s 
results show a temperature coefficient approximately that of the 
van’t Hoff principle between 0° and 37° C. 
The experiments of Matthaei apparently were done with great 
care, and the leaf temperatures and carbon dioxide absorption 
were measured with a high degree of accuracy. Measurements 
of light were much less exact, but Matthaei believed that the 
amounts used in the critical experiments were great enough so 
that light was not a limiting factor. The sources of light 
were two kinds of gas burners. Her unit light intensity was 
a small and arbitrary one, and no measure of its actual inten- 
sity is given. In a foot note Matthaei*' gives the following 
discussion of the measurements of light: 
All the intensities of light subsequently used are expressed in terms of 
this unit intensity by making due allowance for alterations in distance and 
differences in the burners employed. Of course with a compound source 
of light such as an incandescent mantle, such a comparison of intensities 
makes no pretense to accuracy, but may serve as a rough guide to the 
relative amounts of light necessary for maximal assimilation at various 
temperatures, and is absolutely necessary for convenience of reference. 
It will soon also be made clear that knowledge of the exact intensity 
of light being used is not of critical importance in these investigations. 
Some of the irregularities, which will be noted later, may be 
due to inexact measurements of light; but the general concord- 
ance of the results indicates that the measurements were fairly 
accurate. We believe, however, that errors in interpretation 
are responsible for the idea that the rate of assimilation in- 
creases rapidly for rises in temperature between 3° and 33° C. 
The rises in temperature were accompanied by increased inten- 
sities of light, and the latter factor appears to account for the 
changes in rate of assimilation. 
The results of the experiments of Matthaei are given at the end 
of her paper in eleven tables.2? The first deals with respira- 
tion and the others with photosynthesis. Tables II to IV con- 
tain experiments performed with unit intensity of light and at 
various temperatures. Each experiment usually consisted of 
from three to five readings. In these, as in the other tables, 
* Kanitz, A., Uber den Einfluss der Temperatur auf die Kohlendioxyd- 
Assimilation, Zeitschr. Elektrochemie 11 (1905) 689-90. 
= Op. cit. 59. 
* Since’ it will be necessary in this paper to make frequent reference to 
Matthaei’s tables as well as to our own, we shall designate the former by 
Roman numerals, as in the original text, the latter by Arabic numerals. 
, 
