OXYGEN YIELDED BY ANIMALCULES. 183 



rather to meditation, when he perceives that these 

 creatures are elaborately constructed ; that they are 

 organized with an express relationship to their 

 destined mode of life ; and that they enjoy their 

 existence like the fishes of the sea, the birds of 

 the air, or the wild beasts of the desert. 



It has already been stated, that oxygen is the 

 great supporter of animal life, and consequently 

 every living creature is incessantly engaged in con- 

 verting it into carbonic acid by the process of respi- 

 ration. It is estimated that one man daily changes 

 no fewer than 18,000 cubic inches of the oxygen of 

 the air into carbonic acid, by the carbon discharged 

 from the lungs, and consequently, the amount 

 changed by the whole animated population of the 

 globe must be enormous. Other demands are made 

 on this essential element of life, as the oxygen of 

 the atmosphere is indispensable to combustion. It 

 has been calculated that the small town of Giessen, 

 in Germany, with a population of 7,000 inhabitants, 

 yearly changes more than 1,000,000,000 cubic feet 

 of oxygen into carbonic acid, by the combustion of 

 wood as fuel ; and Dr. Carpenter says, in an 

 English manufacturing town, where the proportion 

 of coal used is far greater, the amount would be at 

 least twice as much in proportion to its size. Now, 

 empty jars buried in the city of Pompeii, when 

 it suffered this catastrophe from an eruption of 

 Vesuvius 1,800 years ago, demonstrate that no 

 change has taken place in the proportion of the 



