a given quantity of air, perishes in the shade, after 
having changed about one-third of it into carbonic 
acid, even although this carbonic acid be daily re- 
moved. The cause of the death of the plant, therefore, 
is not, he adds, the presence of carbonic acid ; but 
it dies from having completely deteriorated the air, 
just as an animal would have done *. Plants also, 
he continues, grow in oxygen gas, and, like animals, 
produce carbonic acid in it ; and oxygen gas, instead 
of being destructive to plants, is the support both of 
animal and vegetable life, the true pabulum vita of 
both the living kingdoms of nature f 
258. The opinions of M. Senebier, concerning the 
use of air in vegetation, coincide nearly with those 
which have been just related. He maintains, that 
plants die in nitrogen gas, but live and grow in oxy- 
gen, or in an artificial atmosphere composed of these 
two gases ; and, consequently, he infers, that the 
presence of oxygen gas is indispensably necessary to 
vegetation. He farther maintains, that this oxygen 
gas disappears, and is replaced by carbonic acid gas ; 
and that an atmosphere, rendered noxious to plants 
confined in it, is again made capable of supporting 
vegetation, by withdrawing the carbonic acid, and 
adding to it oxygen gas, in place of that which has 
been consumed. Experience, he continues, teaches 
us, that vegetation never takes place without forming 
carbonic acid, as is proved by placing plants in pure 
oxygen gas | . 
* Exper. Pref. vol. ii. p. 35. t Ibid. 37. 
* Physiol. Vegcl. vol. iii. p. 113. 115. 11& 
