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AMERICAN JOURNAL OF BOTANY 
[Vol. 9, 
organism will not be completed too quickly and the product become unfit 
for food through autolytic decomposition or be broken down by the action 
of micro-organisms. 
The physiological problems of commercial cold storage of plant products 
are, of course, somewhat complex; as in most problems in plant physiology 
the method of attack has been essentially from a chemical standpoint. The 
fundamental principle which apparently governs the relation of many of 
the processes which go on in plants, or which at least seems to explain their 
relation to temperature, was suggested by Van't Hoff.^ This rule is that 
the rate of chemical reaction doubles or trebles for every rise in temperature 
of 10° C. It has been found that many of the processes which go on in 
plants take place in accordance with this rule; that is, within limits there 
is an acceleration of the processes if the temperature is raised and a retarda- 
tion with the lowering of the temperature. For example, the rate at which 
CO2 is given off and oxygen is taken up by plants, which is an indication at 
least of the rate of respiration, is more rapid at high than at low tempera- 
tures. This was shown by de Saussure and by many investigators since 
his time, working with various kinds of plants (see review by Czapek^). 
It has been demonstrated for apples by Morse,^ while Gore^ later carried 
out a series of respiration experiments on a large number of different kinds 
of fruits. He found that the factor for the average increase in the rate of 
respiration for 10° C. rise in temperature, as measured by the amount of 
carbon dioxide liberated, was around 2.37. From the results obtained by 
Gore there would seem to be no question but that there is a marked increase 
in respiration at the higher temperatures. The experiments were, however, 
only of short duration, and it is doubtful that the processes which result in 
the taking up of oxygen and the liberation of carbon dioxide and water 
had reached an equilibrium so that the true measure of the effect of tem- 
perature upon these processes could be obtained. In determining the effect 
of temperature on the rate of respiration, long-time experiments are to 
be recommended as giving a more accurate measure of this process. 
The work of Magness^ indicates that at high temperatures there is 
an accumulation of CO2 in fleshy fruits and vegetables and a very low 
pressure of O2, while at low temperatures the ratio O2/CO2 within the fruit 
is considerably higher. This might well influence the kind of respiration, 
and the energy changes might at high temperatures be by intramolecular 
2 Van't Hoff, J. H. Studies in chemical dynamics (Eng. trans!.). Pp. 286. London, 
1896. 
^ Czapek, F. Biochemie der Pflanzen, ist ed. 2: 397-399. Jena, 1905. 
^ Morse, F. W. Effect of temperature on the respiration of apples. Jour. Amer. 
Chem. Soc. 30: 876-881. 1908. 
^ Gore, H. C. Studies on fruit respiration. U. S. Dept. of Agr. Bur. Chem. Bull. 142, 
pp. 1-40. 
^ Magness, J. R. Composition of gases in intercellular spaces. Bot. Gaz. 70: 308- 
316. 1920. 
