VEGETATION AND THE ATMOSPHERE. 189 
organic matter, absorbed by the nascent tissues, transported by the vessels which 
are forming, takes its place in the organs into whose constitution it enters. Dur- 
ing this whole period, the plant and animal subsist on their own resources, 
drawing nothing from without, and to complete the analogy, they burn a por- 
tion of their own substance. By and by, when all is exhausted, the animal, 
already formed, is prepared to live, as the plant, already delineated, is prepared 
to vegetate, anda common want displays itself at the same moment in both 
existences: that of finding external nourishment. From this point all analogy 
ceases, and the separation of the two kingdoms commences. The vegetable 
ereates and reduces, the animal destroys and oxydizes. 
Let us pursue these analogies. In every flower that opens, botany of late 
has shown us the organs of two opposite sexes which concur, each after its 
character, in the fecundation of the germs. Now, at this moment, when the 
flower seems to borrow that sexual.function of reproduction which we might 
think to be the exclusive privilege of animals, it again imitates them in burning 
the organic material by an active respiration. ‘ All flowers,” said Priestley, 
“invariably exhale a deadly air during the day and during the night, in light 
and in darkness.”’ Daily experience confirms this assertion, and De Saussure 
has shown that this poisonous gas is carbonic acid. At last one of our most 
justly celebrated chemists, M. Cahours, has given us the results of a recent and 
complete study of this respiration of flowers and fruits under all circumstances. 
If itis true that this combustion of organic matter, that this expenditure 
and loss of force, be necessary in itself to accomplish the act of fecandation, it 
is in the sexual organs especially that it should be present. Tixperiment in 
effect has confirmed this conjecture, and it has even been ascertained that it is 
the stamen, the male organ, which dispenses the most. Nor does this fact stop 
there. All combustion disengages heat: it is to their respiration that animals 
owe their high temperature, and it is of course necessary that the stamens and 
pistils should develop heat since they respire. The question was to find ther- 
mometers sufficiently sensitive and a suitable plant. ‘The first vegetable which 
has allowed the verification of a rise of temperature is one which would never 
have been suspected of so much ardor, the pumpkin. Its flowers are large, 
and admit of the introduction of the air-thermometer; some of them are male 
and others female, and the latter have evinced a greater degree of coolness than 
the former. 
Still the gourds, melons, and pumpkins grow warm in but a slight degree, 
and so, it might be said, resemble.the cold-blooded animals. ‘There are plants 
‘which resemble the warm-blooded animals, and these are the Arums. One of 
them, the Arum maculatum, which is found abundant in hedges, is enveloped 
in a rolled leaf which encloses the flower in a chamber, and which prevents the 
heat from being dissipated in space. Observe now the singular phenomenon 
which has been perceived by Lamarck, Sennebier, Bory de Saint Vincent, and 
by De Saussure himself. Habitually the Arum is cold, but at a given moment, 
which must be watched and skilfully improved, the temperature of the plant 
raised from 7 to 8 degrees above that of the atmosphere. Hubert, a truly sa- — 
gacious observer, succeeded in introducing a small and very sensitive thermome- 
ter, sometimes among the stamens, which became heated to 22 degrees, some- 
times among the pistils, which produced an action one-half less. The other 
parts of the plant manifested no special action. By care and watchfulness, De 
Saussure surprised four Arums at the moment of calefaction, and placed them 
under a glass bell filled with air. The glass was immediately covered with a 
moisture which attached itself to the surface, a great absorption of oxygen took 
place, and a correspondent production of carbonic acid. In its chemical acti n 
and the energy of that action, the plant was comparable to a smallanimal. At 
another time De Saussure decomposed the plant into different parts, which he 
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