THE AQUARIUM. 



59 



The Aquarium. 



into the lungs is deprived of a large amount of oxy- 

 gen gas, while at the same time it becomes charged 

 with carbonic acid gas, which is incapable of support- 

 ing animal life. This noxious principle is absorbed 

 by the leaves of plants, where it appears to undergo 

 decomposition; the carbon being retained for the use 

 of the plant, and the oxygen liberated to assist in 

 restoring the atmosphere to its original purity. This 



