166 
DR. DAUBENY ON THE ACTION OF LIGHT UPON PLANTS, 
Neither is this influence exerted exclusively by plants of any particular kind or 
description. I have found it alike in the monocotyledonous and the dicotyledonous, 
in such as thrive in sunshine and those which prefer the shade, in aquatic as well as 
in terrestrial, in cryptogamous and imperfect, such as Ferns and Algse, as well as in 
those of a more complicated organization. How low in the scale of vegetable life 
this power extends is not yet exactly ascertained, but Professor Marcet of Geneva, 
in a late paper, has shown that it does not prevail amongst Fungi. 
The disappearance of carbonic acid in my experiments always more than kept pace 
with the addition to the quantity of oxygen ; but the shortness of time during which 
the plant could be retained in a sufficiently healthy condition, prevented my ascer- 
taining, whether after the carbonic acid had been absorbed by it, a part was not at 
some subsequent period given out again unchanged. 
A small portion might perhaps have been taken up by a thin film of water, which 
I was compelled to keep continually upon the surface of the mercury, in order to 
prevent the latter from destroying, by a disengagement of its vapour, the plant con- 
fined underneath it. This quantity, however, must have been inconsiderable com- 
pared with the amount introduced. 
I shall now conclude, by placing in a tabular form some of the principal, or the 
more illustrative experiments which I have carried on, appending some remarks im- 
mediately suggested by the particular phenomena observed in each. 
