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 George 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 Temperaturerhohung 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. Elektrochemie 13 (1913) 
707, and Zeitschr. Phys. Chem, 70 (1910) 198. 
* Kanitz, A., Temperatur und Lebensvorgange (1916), 
‘Denny F. E., Bot. Gazette 62 (1916) 156. 
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