357 
THE FIRST CHAPTER OF THE GEOLOGICAL RECORD. 
being as now composed mainly of oxygen and nitrogen, along 
with a small admixture of carbonic acid gas, it, on the contrary 
contained so overwhelming an amount of carbonic acid and 
nitrogen gases with only a minute proportion of oxygen (if 
any), as to be totally unfitted for the respiration of air-breath- 
ing animals, for which reason we find the first development of 
life of our globe represented by submarine organisms of tbe 
lowest type, and these followed by a great development of 
vegetation, which by absorbing the carbonic acid gas, and 
decomposing it so as to assimilate the carbon contained in it for 
the benefit of future generations, whilst at the same time the 
oxygen was returned to the air, so purified the atmosphere as 
to render possible the existence of still higher types of animal 
life on the surface of our globe. 
