THE WORLD BEFORE LIFE. 517 



Mars, may be more like the earth, and fitted to support animal and 

 vegetable life. If not inhabited by human beings, they may be pass- 

 ing through their preliminary Paleozoic, Mesozoic, or Cenozoic stages. 

 And there are, probably, though their names are unknown to us, in 

 the distant regions of space, deriving light and heat from suns seem- 

 ing mere points to us, worlds where the early Eozoon rears its cal- 

 careous reefs, the gigantic Labyrinthodon croaks amid the primeval 

 quagmires, and the Connecticut birds are leaving upon the marine 

 mud the imprints of their tridactyle feet. Nor is it unlikely that 

 other species of men inhabit some of these scattering orbs, and are as 

 curious about us and our institutions as we are about them. 



The Nebulous Period. — The usual geological argument for nebu- 

 losity is derived from the attempt to understand the origin of the con- 

 dition of igneous fluidity. If the earth has been cooling from fusion, 

 perhaps this is a cooler condition than the still earlier hotter state of 

 fiery gas. Solids expand into liquids when heated, and liquids may 

 become gases for the same reason. This gas, however, may not neces- 

 sarily have been hotter than when condensed. The particles of matter 

 must be the same when volatilized, as in both the liquid and solid states. 

 Every substance now existing beneath the atmosphere must have 

 been present — the compact ledges of the firmly-seated hills — the 

 stone-walls of ancient cities — the water of the ocean — the oily fluid 

 spouting from the bore-holes of Western Pennsylvania — the very par- 

 ticles of the paper containing this sentence printed upon it — and even 

 the elemental constituents of our bodies, so fearfully and wonderfully 

 made — all these and every thing material may have been commingled 

 with the atmosphere, hovering about in a vaporous form, the compo- 

 nents of a nebula, or comet. 



In the attempt to surmise the actual condition of the elements at 

 the beginning of the nebulous period, two views may be held, accord- 

 ing as we prefer to adopt a chemical or mechanical theory of their 

 origin. If one does not care to imagine the atoms called into exist- 

 ence in a heated condition, he may suppose that matter first appeared 

 with the common frigid temperature of space, or about one hundred 

 degrees Fahrenheit below the freezing-point of water, and that the ele- 

 ments were uncombined. Newly born, these particles would imme- 

 diately commence to display their affinities, and the result would be 

 explosive combinations, giving off" intense light and heat. The latter 

 force permeating the elements, would soon reduce them, first to igneous 

 fluidity, and then into heated vapors. Every atom flying away from 

 every other one, on the principle of " dissociation," would give rise to 

 a nebula of enormous dimensions in a comparatively short time from 

 these cosmic materials. After the formation of the nebula, the series 

 of changes about to be described would commence its rounds. 



A mechanical theory is presented by the distinguished philosopher, 

 Dr. J. R. Mayer, author of a treatise upon " Celestial Dynamics." 



