pe gm ed tt 
THE PHILIPPINE 
JOURNAL OF SCIENCE 
C. BoTANY 
VoL. XII JANUARY, 1917 No. 1 
THE APPLICATION OF PHOTOCHEMICAL TEMPERATURE CO- 
EFFICIENTS TO THE VELOCITY OF CARBON DIOXIDE | 
ASSIMILATION 
By WILLIAM H. Brown and Grorce W. HEISE 
(From the College of Liberal Arts, University of the Philippines, and from 
the Bureau of Science, Manila, P. I.) 
THREE TEXT FIGURES 
The van’t Hoff principle,‘ which states that the rate of most 
chemical reactions at ordinary temperatures (between 0° C, and 
180° C.) is approximately doubled or trebled for each increase 
of 10° C. in temperature, has been applied to many processes 
taking place in living organisms. Its application to plant proc- 
esses has been emphasized by Blackman,? while Loeb and his 
coworkers * have discussed its relation to many processes in ani- 
mals. Kanitz* has written a monograph on the relation between 
temperature and life processes. We have not been able to con- 
sult this book. Denny * in reviewing it says: 
Consideration is given first to the effect of temperature upon the rate 
‘Van’t Hoff, J. H., Studien zur chemischen Dynamik (revised by Cohen, 
E.) (1896) 129: “* * * eine Temperaturerhéhung um 10 Grad ver- 
doppelt, resp. verdreifacht die Reaktionsgeschwindigkeit.” 
* Blackman, F. F., The metabolism of the plant considered as a catalytic 
reaction, Science N. S. 28 (1908) 628-636. 
* For a list of references on this subject, see Loeb, J., et al., Science N. S. 
28 (1908) 645-648; also Kanitz, A., Zeitschr. Baltvckeanle 13 ye) 
707, and Zeitschr. Phys. Chem. 70 (1910) 198. _. 
* Kanitz, A., Temperatur und Lebensvorginge (1915). 
* Denny F. E., Bot. Gazette 62 (1916) 156. 
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