XXXII 



THE INFLUENCE OF RADIATION ON PLANT 

 RESPIRATION AND FERMENTATION 



Charles J. Lyon 



Department of Biology, Dartmouth College 



Introduction. Influence of radiation on respiration. Radiation and fermentation. 

 Summary. References. 



INTRODUCTION 



In general, the influence of radiant energy on katabolic processes 

 is incompletely understood because of lack of proper experimentation 

 in the field. Either the necessary tests have not been carried out or the 

 experiments have been so inadequate in number or precision that the 

 results are inconclusive or unreliable. This is not strictly true for all 

 types of radiation, however, and in the following paragraphs distinctions 

 are made as definitely as possible between well-supported evidence 

 and that based on only a few experiments. These distinctions have 

 been made even at the risk of injustice to some workers, but it is hoped 

 that such errors will be excused in the interests of a conservative estimate 

 of results obtained in a difficult field of experimentation. 



INFLUENCE OF RADIATION ON RESPIRATION 



Light. — The attempts to measure the influence on respiration of 

 radiation from sources of light have resulted in the accumulation of a 

 mass of inconclusive and contradictory evidence. In general, the 

 earlier results pointed to a decrease in intensity of respiration as measured 

 by production and release of CO2 while later and more careful experimen- 

 tation has indicated the absence of any direct effect of the visible rays. 



These analyses have been exceedingly difficult and in fact limited 

 almost entirely to nongreen plants because of the simultaneous action 

 of light in photosynthetic processes. At the same time, there has been 

 a regrettable failure, even in some of the work of recent years, to make 

 the conditions of the experiments such as to preclude the influence of 

 radiation other than that of the visible spectrum. Consequently the 

 results are decidedly inconclusive, although it seems evident that there 

 can be no appreciable direct effect of light on normal respiration. 



Work reported previous to 1902 may be passed over with safety 

 because it was so fragmentary and inexact. It is carefully .and fairly 



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