167 



tihey gradually suffer decomposition, forming car- 

 bonic acid and carburetted hydrogen gases ; and the 

 faculty of germinating is then destroyed. If, far- 

 ther, they be first steeped in water, and then placed 

 in nitrogen gas (5.), carbonic acid is, in like man- 

 ner, formed ; and the same acid is likewise produced 

 when they are simply plunged into a tube of mer- 

 cury without the aid of any elastic fluid at all ; but, 

 in neither of these cases, do they exhibit any sign of 

 germination. Whatever, in these experiments, may 

 be the source from whence the oxygen gas forming 

 the acid is derived, it must be granted that the seed, 

 in every case, furnished the carbon. But this acid 

 is likewise produced when steeped seeds are made to 

 germinate in atmospheric air (6.), or in oxygen gas, 

 where nothing also but the seed is present from 

 which the carbon can be derived : hence therefore, 

 it follows, that the seed, during its germination, as 

 well as under decomposition, must .be able to supply 

 carbon. 



133. Does then the carbon, which thus contri- 

 butes to the formation of the acid, issue directly 

 from the seed, and unite with the oxygen gas of the 

 air exterior to its substance ? or does this oxygen 

 gas previously enter into the seed, and, combining 

 with its carbon, again escape from it in the form of 

 carbonic acid ? If the view which we have taken of 

 the structure of seeds, and of the manner in which 

 the air is affected by their growth^ be just, this latter 

 supposition .cannot be entertained : and, from the 

 facts stated in the foregoing paragraph, it is suffi- 

 ciently clear, that, in many cases, the entrance of 

 oxygen gas into the seed is by no means necessary 



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