220 EECENT RESEARCHES ON THE RESPIRATION OF PLANTS. 



observing whether carbonic aeid gas is not reduced during the 

 long summer evenings and mornings. The following table 

 shows the results of some experiments undertaken with this view, 

 and they are given, though, from the small number of the experi- 

 ments, nothing decided can be inferred. 



Experiments which tend to shmo that the carbonic acid exhaled 

 is partly reduced during the summer evenings and mornings. 



The reduction of carbonic acid being less active in the shade 

 than in the sun, I was curious to learn if the diffused light, 

 occasioned by the eclipse of the 28th of July, caused an increa.se 

 of undecomposed carbonic acid in the air surrounding the plants. 

 For this purpose four apparatus were got ready just as the moon 

 passed before the sun, and were examined the moment the eclipse 

 was completely over. The experiment lasted for three hours, 

 and the feeble solar rays were almost constantly intercepted by 

 liglit clouds. The results obtained are given in the following 

 table. " 



