i[)5 
lutely necessary to their life. Atmospheric air 
taken into the lungs of animals, or passed in solu- 
tion in water through the gills of fishes, loses 
oxygene ; and for the oxygene lost, about an 
equal volume of carbonic acid appears. 
The effects of azote in vegetation are not dis- 
tinctly known. As it is found in some of the 
products of vegetation, it may be absorbed by cer- 
tain plants from the atmosphere. It prevents the 
action of oxygene from being too energetic, and 
serves as a medium in which the more essential 
parts of the air act : nor is this circumstance un- 
conformable to the analogy of nature ; for the 
elements most abundant on the solid surface of the 
globe, are not those which are the most essential 
to the existence of the living beings belonging 
to it. 
The action of the atmosphere on plants differs 
at different periods of their growth, and varies with 
the various stages of the developement and decay 
of their organs ; some general idea of its influence 
may have been gained from circumstances already 
mentioned : I shall now refer to it more particu- 
larly, and endeavour to connect it with a general 
view of the progress of vegetation. 
If a healthy seed be moistened and exposed to 
air at a temperature not below 45°, it soon ger- 
minates ; it shoots forth a plume which rises up- 
wards, and a radicle which descends. 
If the air be confined, it is found that in the 
process of germination the oxygene, or a part of 
it, is absorbed. The azote remains unaltered ; no 
o 2 
