1913] LIVINGSTON—T EMPERATURE COEFFICIENTS 3590 
velocity of a given chemical process doubles with each rise of 10° 
in temperature, but that the process is retarded by the accumulation 
of the products of the reaction. In such a case it is obvious that, 
with increasing temperature, a point might sooner or later be 
reached at which the removal of these products might not proceed 
rapidly enough to allow the full temperature effect to become 
manifest. Thus, the rate of removal of the products must be 
adequately increased with the rise in temperature; otherwise the 
effect of this rise becomes masked by the effect of another variable, 
namely the mass action of the products. From these considerations 
it does not seem surprising that complex vital processes such as 
growth may frequently fail, under natural conditions, to exhibit the 
usual chemical temperature coefficient. In some of these cases, 
proper alterations in other environmental factors might disclose the 
otherwise obscured coefficient; in other cases the limitations might 
lie in the nature of the protoplasmic mixture, and the obscuring of 
the coefficient might persist in spite of any attempt at external 
adjustment. 
The most satisfactory study on the influence of temperature 
upon growth rates in plants, so far as our knowledge goes, is that 
of Price,” who determined temperature coefficients for the opening 
of flower buds of the plum, peach, apple, and other fruits, and 
found the van’r Horr-ARRHENIUS principle generally to hold. 
Beginning with resting buds, the time period required for blooming 
is reduced about one-half for each rise in temperature of 10° C. 
The same author figures maize seedlings which suggest that the rate 
of growth in length of shoot about doubles for each rise of 10°. 
The present aspect of the entire question leads us to the con- 
clusion that there are many cases in which growth rates and other 
complex processes in plants and animals exhibit temperature 
coefficients of about 2.0, and that, in other cases, this same coef- 
ficient may probably be operative, but may be obscured by the 
limiting effect of some other environmental or internal condition. 
It must also be supposed that temperature coefficients of other 
orders of magnitude may be encountered, not only for complex life 
* Price, H. L., The application of meteorological data in the study of physio- 
logical constants. Ann. Rep. Virginia Agric. Exp. Sta. 1909-1910. 
