RADIATION AND RESPIRATION 



1069 



duction of the irradiatod mixture of glucose, water, and a bottom yeast 

 was so great that the temperature fluctuation of 3° or 4°C. was of no 

 importance, especially since the rise in temperature was nearly as great in 

 the control flask. 



It should be noted that the rather brief report of this work by Lindner 

 makes no mention of a screening of the radiation from the lamp and it is 

 probable that other rays entered the quartz flask in which the fermenta- 

 tion took place. The heating effect of the infra-red appears to have 

 been practically eliminated, but there is some uncertainty as to what 

 participation other rays may have had in the effect. However, the 

 effect is so great that at least a part must be due to the ultra-violet rays. 

 Possible direct action on the glucose was eliminated by suitable tests. 

 Furthermore, study of the condition of the irradiated yeast cells after 

 24 hr. exposure showed that 20 to 30 per cent of them are injured or killed, 

 as though they had been worked out by the high rate of fermentation. 



The data are given for only a single experiment. A solution of 

 30 gm. of glucose in 300 cc. of water was inoculated with 5 gm. of pressed 

 yeast and allow'ed to stand for 10 hr. before the experiment began. A 

 control mixture w^as treated in the same way and its CO2 production 

 measured simultaneously with that of the mixture exposed to the lamp. 

 The results were evident from the start as Table 3 shows: 



Other tests are reported on the action of the radiation on beer wort 

 inoculated with this same yeast. The differences in favor of the irradi- 

 ated yeast were less than for glucose solutions but w^ere still convincing 

 and consistent. Until more precise tests are made, especially by the 

 use of suitable filters, it may be assumed that there is some unusual 

 effect of ultra-violet on fermentation, possibly related to the similar 

 effect on the respiration of pea seedlings. 



