18 



affords a correction for those occasional variations 

 which our atmosphere experiences, and insures the 

 preservation of vegetables in all circumstances in 

 which they may naturally be placed *. 



16. Such being the principal factfc in germination 

 which bear a relation to the changes which the air 

 suffers, let us next inquire in what manner they are 

 to be accounted for or explained ; and first of all, 

 what becomes of the oxygen gas that disappears ? 

 Mr Gough believes that seeds, during their germi- 

 nation, absorb oxygen gas from the air, retain a part 

 of it, and reject the remainder, charged with car- 

 bon f. Now although seeds have a power of im- 

 bibing and exhaling water, there is no evidence of 

 their possessing a structure fitted to absorb and expel 

 aeriform fluids ; neither is there any proof of such 

 fluids at any time existing in them. If the air be absor- 

 bed in its entire form, some receptacles ought to be 

 shown in the seed for retaining and decomposing it,. 

 and from which the nitrogen gas could be after- 

 wards expelled : or, if the oxygen gas alone be con- 

 ceived to enter, then it may be asked, by what 

 power of absorption it could be separated from the 

 nitrogen gas with which it was previously combined ? 

 Mr Cruickshank inclines also to the belief, that the 

 oxygen gas is chiefly absorbed by the seed, although, 

 part may, he says, be consumed in the formation gr 

 the carbonic acid \ ; and we learn from his experi- 



* Sur la Germination, p. 119. et seq. 



f Manchester Memoirs, vol. iv. p. 319. 



J Experiments on Sugar, in Rollo on Diabetes. 



