174 
DR. DAUBENY ON THE ACTION OF LIGHT UPON PLANTS, 
With respect to the comparative influence of similar plants indirect and in diffused 
light, I have as yet made only a few experiments, but the results of these few seem to 
indicate that even under the latter circumstances an increase in the amount of oxygen 
will be sometimes produced by them. 
Per cent. 
Thus a jar, in which a Geranium had been confined, contained, after ex- 
posure for four hours to direct light, of oxygen 25 
Whilst another, in which a similar plant had been placed for the same time 
in diffused light, contained 19*5 
On the other hand, 
Two jars, containing Myrtles, after being placed in direct light for eight 
hours, had acquired of oxygen, 
No. 1 2375 
No. 2 26 00 
Two similar jars with Myrtles in diffused light, exposed for the same time, 
contained, 
No. 1 20-0 
No. 2 
23-0 
Two jars with Polypodium dryopteris, the one in direct, the other in diffused 
light, each contained of oxygen 22’0 
In conclusion, it may perhaps be well to present in a tabular form the different 
questions which this inquiry embraces, pointing out how far each may be considered 
as answered, either by the experiments of preceding investigators, or by those de- 
tailed in the present memoir. 
