29 



able state of preservation, after huudreds of years of 

 burial or submersion in lakes and swamps or marshes. 

 The more closely these deposits are studied, the more 

 enormous they are found to be. In the tropical regions 

 organized bodies decay rapidly, but above 45 degrees of 

 of latitude, vegetable matter begins to accumulate in vast 

 quantities, and animal bodies to be more frequently pre- 

 served. 



''The quantity of timber which is conveyed from the land 

 to the sea, by the sinking of ships of a large size, is enor- 

 mous, for it is computed that 2,000 tons of wood are re- 

 quired for the building of one 74 gun ship ; and reckoning 

 50 oaks, of 100 years growth, to the acre, it would require 

 40 acres of oak forest to build one of these vessels." The 

 amount of organized matter thus preserved can only be 

 conceived by a knowledge of naval statistics. 



Even where an organized body seems to be entirely de- 

 composed — part of it returning to gaseous and part to 

 liquid form — solid parts of it may be washed away and 

 buried so as to remain undecomposed for ages, for if they 

 do change thus buried away, it will be but a molecular 

 change that can not restore to their original forms their 

 liquid or gaseous elements of matter. 



The processes of petrefaction are as yet but very imper- 

 fectly understood. It is more than probable some subtle 

 chemical or atomic change takes place in the internal 

 structure of fossil remains. The formation of flints, ap- 

 parently upon the nucleus of an organic body upon the 

 floor of the seas, at various epochs during the chalk de- 

 posits, is remarkable and suggestive. It is said b}' Mr. 

 Johnston that stale bread contains exactlv the same amount 

 of water as fresh bread — about one half — but that its liard- 

 ening is caused by molecular change, and not by evapora- 

 tion or the removal of any of its elements. This may be 

 considered an inapt and homely illustration, but if such a 

 change transpires in the open air where the elements would 



