A52 On the upright Growth of Vegetables. [Junz, 
experiments, they inform us that, on an average, vegetables evapo- 
rate daily a quantity of water equal to half their weight. Spear- 
mint was found to evaporate its own weight; and a cabbage plant 
weighing I lb. 9 oz. perspired 11b. 30z. It is scarcely to be 
doubted that water, which contains two of the elemental ingre- 
dients of vegetables, viz. oxygen and hydrogen, does by decompo- 
sition furnish nourishment to the plant; but its principal office in 
the progress of vegetation seems to be to serve as a menstruum for 
enabling the more fixed elements, carbon, lime, phosphorus, &c. 
to be imbibed by the roots, and circulated by the other organs. 
Having accomplished this important service, it unites with the 
excess of caloric, by which it is converted into vapour; and each 
lingering gaseous particle, separating with difficulty from its former 
companion, communicates to every part of the plant an upright 
direction, in which position it is permanently fixed by the formation 
and increasing inflexibility of the woody fibre. 
It 1.ay appear surprising that such a quantity of water should be 
evaporated from vegetables, whilst their temperature remains not 
mouch higher than that of the surrounding atmosphere; but it is 
to this evaporation we must ascribe the low temperature which the 
plant preserves in the midst of circumstances calculated to raise it 
to a much higher degree. These circumstances have been deve- 
Joped by that ingenious naturalist Mr. Daniel Ellis, who has proved 
that during vegetation in all stages there is a combination of oxygen 
and carbon, ‘‘ the formation of carbonic acid being the universal 
law of living or organized bodies, and seeming to be necessary to 
their life’? When the oxygen thus combines, it parts with its 
’ ealorie; and from experiment it has been found that the calorie 
evolved during the formation of 30 cubic inches of earbonic acid 
gas will melt 1 oz. of ice. Thata large quantity of carbenie acid 
gas is daily formed from vegetables, will at once be apparent when 
it is recollected that, in consequence of the absorption of oxygen 
by this process, independent of what is formed from the decompo- 
sition of water, the presence of a few plants in a room, notwith 
standing the supply from the ordinary circulating currents, soon 
renders the air unfit for respiration, and has net unfrequently been 
the cause of death. The heat thus produced would certainly be 
destructive of the plant, were it not carried off by the vapour; so 
that in the vegetable kingdom we find the same beautiful provision 
which, in the respiration of animals, protects the vital parts from the 
too powerful action of caloric. 
We may hesitate, notwithstanding, to admit evaporation as a 
cause adequate to produce such an effect as the perpendicular 
growth of plants, though it is astep gained in our progress if it be 
admitted that in any degree it has that tendency. But we may feel 
re-assured, when we recolléct that not only has evaporation the 
effect of producing buoyancy, in the particles adhering to the 
vapour; but that it is the only cause known connected with vegeta- 
tion, which does certainly operate to produce such buoyancy, It 
