THE TEMPERATURE COEFFICIENT OF THE DURATION 
OF LIFE OF CERAMIUM TENUISSIMUM 
ARTHUR H. AYRES 
Reaction velocities at various temperatures have become of 
much interest to biologists, on account of the possibility they 
present for the identification of certain physiological processes as 
chemical or physical, since it has been found that certain common 
physical and chemical reactions have rather characteristic tempera- 
ture coefficients. Thus, if we suspect that a certain reaction is 
due to a chemical process, we can determine whether or not the 
velocity of the reaction at various temperatures is of the magni- 
tude demanded by a chemical reaction. Since the temperature 
coefficients for all chemical reactions do not always have the same 
order of magnitude as demanded by the van’t Hoff rule on the 
dependence of the rate of reaction of chemical processes upon 
temperature (9g), the test is not wholly conclusive, but indicates 
rather a probable explanation of the phenomenon in question. 
Animal physiologists in recent years have given much attention 
to temperature coefficients, but very little work has been done 
upon this subject by plant physiologists. CLAUSEN (2) was the 
first to show that the rate of evolution of carbon dioxide from 
seedlings and buds was about doubled with an increase of 10° C. 
Miss Marruaerr (5) found that van’t Hoff’s rule applied to the 
fixation of carbon dioxide by leaves in sunlight and to the evolution 
of this gas by leaves in the dark. Price (7) determined the 
temperature coefficient for the opening of flower buds, and found it 
to have the magnitude demanded for a chemical reaction. 
It will be seen that these experiments deal with growth phe- 
nomena. Logs (4) was the first to call attention to the fact that 
the temperature coefficient of the duration of life of sea urchin 
eggs differs widely from that of their development, the temperature 
coefficient of development being 2.86 for a rise in temperature 
of 10° C., while that of duration of life is nearly 2 for a rise in 
temperature of 1°C. Moore (6) found that the temperature 
65) [Botanical Gazette, vol. 62 
