24 



not arise from the presence of nitrogen gas, for that 

 gas exerts (5.) no injurious operation. Neither, al- 

 though Mr Achard found, that germination did not 

 take place in carbonic acid, can the presence of that 

 substance be considered as positively destructive to 

 the process ; for the same effect occurs when nitro- 

 gen gas only is present, and even in vacua without 

 the direct agency of any gas at all. M. Huber too 

 found, that when oxygen gas or common air, in 

 certain proportions, was mixed with carbonic acid, 

 seeds grew in it very well * : and in all our experi- 

 ments, where the carbonic acid produced by germi- 

 nation was suffered to remain, the seeds ceased to 

 grow, not from the presence or abundance of that 

 acid, but from the diminished quantity or total ab- 

 sence of the oxygen gas out of which it was formed. 

 Since, indeed, the absence of that gas is sufficient to 

 account for the cessation of the process, it is unphi- 

 losophical, because unnecessary, to resort to the a- 

 gency of any secondary cause ; and as both carbo- 

 nic acid and nitrogen gas must always of necessity 

 be present in germination, it is not to be expected 

 that either the one or the other should exert any in- 

 jurious operation. 



22. Neither, because carbonic acid is always pre- 

 sent, is it, on that account, to be held as at all essen- 

 tial to germination ; for the same might be urged in 

 favour of nitrogen gas, which neither produces (5.) 

 nor suffers change. The constant existence of this 

 acid in the atmosphere is no proof of its aiding ger- 



Sur la Germination, p. 56. 



