62 FOOD OF THE VEGETATING PLANT. CHAP. f. 



manner gave a similar result ; and yet these plants 

 vegetated to an indefinite time in an atmosphere of 

 common air. 



From the above experiments it seems to follow 

 that nitrogene gas, at least in its pure state, is un- 

 favourable to vegetation ; but particularly in the 

 shade. And yet there are some plants, such as the 

 Vinca minor, Ly thrum Salicaria, Inula dysenterica, 

 Epilobium hirsutum, and Polygonum Persicaria, 

 that seem to succeed equally well in an atmosphere 

 of nitrogene gas as in an atmosphere of common 

 air. A plant of the Lythrum Salicaria, selected 

 for the purpose of experiment, was put into a re- 

 ceiver containing sixty-five cubic inches of nitrogene 

 gas, of which it displaced about one-eighth of a 

 cubic inch. It had its roots immersed in about an 

 ounce of water, and was exposed to the rays of the 

 sun, when it grew and became so luxuriant that it 

 was more than once necessary to remove it into a 

 larger receiver. But this luxuriance of growth 

 seems incompatible with the previous conclusion. 

 At the end of two months however, when the ex- 

 periment was stopped, the receiver was found to 

 contain the same quantity of nitrogene gas as at 

 the beginning. The plant could have derived no 

 nutriment, therefore, from its atmosphere. But 

 this was the case also in all of the preceding ex- 

 amples. There was no diminution in the original 

 quantity of nitrogene introduced into the receiver. 

 It follows therefore that nitrogene gas, at least in 



