it was found, that in the space of >ne week the seeds 

 had grown to the height of two or three inches *. 

 Mr Gough observed, that steeped seeds put into a 

 close vessel so as to fill it, did not grow, but that 

 when a smaller number v/as put into the vessel, and 

 its mouth covered loosely with a piece of glass, so 

 that the air had free access to the seeds, they ger- 

 minated very freely ; experiments which we have 

 often repeated, and always with the same results. 

 Since, then, air is essential to the progress of germi- 

 nation, and it is known that this elastic fluid consists 

 of two elementary parts, we may next inquire what 

 changes this air undergoes, and whether one only, 

 or both its parts, be required in this process. 



5. It appears from the experiments of Mr Achard 

 and others, that no seed will germinate in nitrogen 

 gas, which gas forms nearly four-fifths of the air of 

 the atmosphere. Mr Gough placed some barley- 

 seeds, previously steeped in water, in a jar of this 

 gas. At the end of three days they had suffered no 

 change ; the bulk of gas was not perceptibly altered, 

 nor did it diminish by agitation in water, which 

 showed that no carbonic acid was formed : but when 

 the place of the nitrogen gas was supplied by atmos- 

 pheric air, the same seeds germinated freely, and 

 formed carbonic acid, just as if they had ne- 

 ver been confined in nitrogen gas at all. If, how- 

 ever, they remained three or four days in this gas 

 when the weather was warm, they began to putrefy 

 in the same manner as when retained too long in 



* Lowthorpe's Abrid. Phil. Trans, vol. ii. p. <2Q6 f 

 A3 



