1 



4 Where did Life Begin f 



continent to another, and thus account for 

 what is very evident, viz. : That many widely 

 distributed species and varieties have come 

 from the same locaHty and had a common 

 ancestry and origin. Is it not evident that 

 the very plants and animals (in a tribal sense) 

 whose migrations they have been engaged in 

 unravelling, were as much older than ice and 

 snow on the earth as it would require in time 

 to lower the av'erage temperature over a vast 

 area from a tropical to a frigid climate ? 



To give some idea of this immense lapse 

 of time as before intimated, it may be stated 

 that as crystallized rock is a much poorer con- 

 ductor of heat than molten rock, so when the 

 polar and temperate zones became once fairly 

 encrusted, the main escape of heat from the 

 earth would forever thereafter have been 

 through the still hotter equatorial belt which 

 was surely then receiving, as now, the in- 

 tensest heat of the sun ; and so it must have 

 remained, other things being equal, for an 

 immense and incalculable period of time be- 

 fore its complete encrustation ; and even there- 

 after its over-heated currents of air and water 



