SECf. VI. ELABORATION OF OXYGENE. 167 



the gas thus inhaled is not yet assimilated to the 

 vegetable, but is given out to the atmosphere by 

 the leaves. Hence also, if an entire plant root, 

 stem, and branch, is introduced into the receiver, 

 so as that the root shall be immersed in the water 

 by the extremity only, and in contact, for the most 

 part, with the atmosphere of the receiver, the 

 oxygene of this atmosphere is not diminished ; be- 

 cause the portion which is abstracted by the root is 

 restored again by the leaves. The oxygene inhaled 

 by the root, then, is not again evolved by it, nor im- 

 mediately assimilated to the vegetable substance; 

 but is conducted to the leaves in the state of car- 

 bonic acid, and there elaborated, or given out to the 

 atmosphere. 



If the branch of a woody plant, taken and lopped On the 

 off in the spring immediately before the expansion 

 of the buds, is inclosed in a receiver filled with com- 

 mon air together with a small quantity of water to 

 supply it with nourishment, it will develope its 

 leaves as if vegetating in the open air. But it will 

 not effect this developement if it is placed in a 

 receiver filled with nitrogene or hydrogene gas ; in 

 which it will, on the contrary, soon exhibit symp- 

 toms of putrefaction, by giving out a quantity of 

 nitrogene and carbonic acid gas. The developement 

 then, in the former case, must consequently have 

 been effected by means of the inhalation of oxygerte, 

 which it thus appears that the stem and branches 

 are capable of effecting, even though stripped of 



