RADIATION AND RESPIRATION 1061 



Table 1. — Data from de Bokr 

 Using 20 very small specimens of Laccaria amelhysta; respiration vessel 325 cc; suction 



velocity (Air Circulation) 3 liters per hr. 

 (3, cf. Table 21, page 211) 

 Time CO2 evolved, cc. 



From 10.00 to 12.00 -^4.5 

 From 12.00 to 14.00 ->4.35 



From 14 . 00 to 16 . 00 ^ 4 . 35 <- light of 800 MC. 

 From 16 . 00 to 18 . 00 -^ 4 . 35 



From 1 8 , 00 to 20 . 00 -> 4 . 5 <- light of 6000 MC. 

 From 20 . 00 to 22 . 00 ^ 4 . 35 



vessel submerged in a water bath held at 35°C. by a thermostat. How- 

 ever, the number of measurements is so small and the acceleration 

 reported is so slight that the evidence is not convincing. Still it should 

 be noted that this work was done with an organ of a vascular plant, 

 while practically all the tests reported above were confined to fungi. 

 It is still possible that this difference in behavior will be confirmed by 

 future experiments which need to be performed before a general conclu- 

 sion can be reached. The slight increase reported by Day (4) with 

 germinating grain should be checked by tests with modern apparatus 

 and attention to the influence of growth rates. Flowers without green 

 parts or marked phototropic responses should also be subjected to careful 

 tests and it is possible that etiolated plants or seedlings grown in darkness 

 on solutions of organic compounds could be tested by exposure to light 

 which would be too brief to cause development of chlorophyll before a 

 response to illumination could be detected. 



There is a possible indirect effect of illumination on respiration, first 

 brought to our attention by Spoehr (20) who showed that air ionized 

 by the sun's rays gave a slightly greater rate of respiration than night 

 air or deionized air. Spoehr's theory was given support by the work 

 of Middleton (13) with barley seedlings and Whimster (24) with leaves 

 of Pelargonium, but not by that of Sapozhnikova (18) with wheat seed 

 or of de Boer (2) with fungi. In any case the effect is small and indirect. 



A specific photochemical effect of light on the respiration of yeast 

 checked by carbon monoxide was demonstrated by Warburg (22) and 

 confirmed by Keilin (7). When the respiration is stopped by CO, the 

 latter forms a chemical union with the oxidase system and either light 

 from a 50-candle power light or daylight will release the CO and allow 

 respiration to proceed. The short wave-lengths are more active while 

 the red rays are inactive. 



This effect for a pathological condition has no influence on the general 

 conclusion that light does not affect the respiration of plants (except 

 for the incompletely tested possibility that tissues of the higher plants 

 are slightly affected) other than through the increased supply of carbo- 

 hydrates produced by simultaneous photosynthesis in green tissues. 



