the precise period at which germination ceases in 
oxygen gas ; or to determine what part of the acid 
is really formed by the process of germination, and 
what by the spontaneous decomposition of the seed. 
Consequently, the attempts to establish an identity of 
quantity, between the oxygen lost and the acid pro- 
duced, must be fallacious, and the conclusion thence 
derived unworthy of credit *. 
211. We readily admit this difficulty in estimating 
the quantity of carbonic acid ; but a due attention 
to circumstances will, we think, enable us entirely to 
remove it. To this end, it is important to observe, 
that, where this acid is formed without the presence 
of oxygen gas, no apparent change is effected in the 
seed, but the bulk of air is increased ; where, on the 
contrary, it is produced in that gas, the oxygen dis- 
appears, and the evolution of the seed goes on, but 
the volume of air suffers little or no variation. Whe- 
ther, therefore, we attend to the sensible effects pro- 
duced in the air, or to those which occur in the seed, 
the difference is most striking ; and so likewise must 
be the causes from which such difference proceeds. 
These causes, we have argued (19.), arise from the 
seed, in one case, affording only carbon, which unites 
with the oxygen gas of the air, and converts it into 
carbonic acid ; while, in the other case, this acid gas 
is at once furnished by the seed alone. The one re- 
sult, therefore, accompanies the evolution of the seed, 
the other attends its spontaneous decomposition; but 
it is only with the former process that we are at pre- 
sent concerned. 
* Nicholson's Journal, vol. xxiii. p. <217 ft seq. 
