26 
234. In the foregoing experiments, no circum* 
stance, as far as we can discover, was present, which 
could interfere with the natural progress and result 
of vegetation. The plants remained growing in the 
earth, and except that they were confined in a small 
volume of air, every other circumstance was natural 
to them. Nor was any substance admitted into the 
glass vessels, except the plants, which could, in any 
material degree, affect the air, unless it be conceived 
that the small quantity of luting, employed to close 
the junctures, operated in that way. We found in- 
deed, that the liites we employed did, in a small de- 
gree, act on the air ; but we satisfied ourselves that the 
small quantity used, compared with the volume of 
air employed, and covered, as it often was, with a 
considerable depth of water, could not, in any mate- 
rial degree, interfere with the expected results. To 
do away, however, the possibility of error from this 
cause, we varied the method of experiment in the 
following manner, in which no luting was employed. 
235. We procured some young succulent cuttings of 
willow, and placed several of them together in phials 
of pure water, which phials were then confined un- 
der separate jars of atmospheric air, inverted in water. 
The jars were then set aside in the shade on the 9th 
of July. By the 16th of that month, the cuttings had 
thrown out small rootlets, which, by the 22d, were, 
in some instances, nearly an inch in length. On the 
23d, the air in one jar was examined. It lost -m by 
agitation with lime water, and afterwards, by the slow 
combustion of phosphorus, it lost eleven parts more, 
making TV? in. all \ so that nearly half the oxygen 
