METEORS. l8l 



moving about through space. If at the present instant 

 no life existed upon this earth, one such stone falling 

 upon it might, by what we blindly call natural causes, 

 lead to its becoming covered with vegetation. I am 

 fully conscious,' adds the learned mathematician, in 

 conclusion, 4 that many scientific objections can be 

 urged against this hypothesis ; but I believe them to 

 be all answerable, the theory that life originated on 

 this earth through moss-grown fragments from the 

 ruins of another world may seem wild and visionary ; 

 all I maintain is, that it is not unscientific.' 



Before considering the statement as to the move- 

 ments of masses through space, on which, as on 

 certainties, Sir W. Thomson has based his hypothesis, 

 it may be well to touch briefly on a few incidental 

 considerations. In the first place, it will be noticed 

 that the hypothesis accepts to the full the principle of 

 development as respects life on the earth. For it pro- 

 fesses only to explain how the earth may have become 

 covered with vegetation, that vegetation being pre- 

 sumably developed from a few primal forms, introduced 

 by meteoric agency. The lower forms of animal life 

 would then be developed from certain forms of 

 vegetable life, and thence higher forms of animal life, 

 and (on our earth at least) man as the highest form. 

 It is, again, to be noticed that the theory does not 

 profess to explain the origin of life generally, but the 

 origin of life upon our earth. Of the two orbs 

 whose collision led to the scattering of seed-bearing 

 meteorites for our earth's benefit, one, at least, must 



