LIFE ON THE EARTH. 129 



We encounter at this point the question as to 

 ' Spontaneous Generation,' a momentous enquiry, be- 

 queathed to us in a vague form from antiquity, and 

 recently revived under conditions of very delicate 

 experimental research. Can matter of any kind, under 

 any circumstances, generate life without the presence 

 of the ova or germs of prior life ? Though the enquiry 

 lias applied itself only to the lower forms of infusoria, it 

 is one of deep interest, whatever the solution may be 

 involving, as it does, in connexion with recent theories 

 of derivation and development, the whole question as 

 to the origin of life on the earth. The researches of 

 M. Pasteur, admirably guarded against all contingencies 

 of error, are in my mind next to conclusive in favour 

 of the old dogma, ' Omne animal ab ovo.' But the 

 opposite view sustained by Pouchet and others cannot 

 be put aside without further enquiry. And such is 

 now in progress, by methods which strikingly attest the 

 exquisite exactness of modern experiment. 



Nothing more startles contemplation than the quan- 

 tity of life upon the earth. Around us, above us, be- 

 low us air, ocean, lake, river, mountain, plains, and 

 forests all nature teems with it ; from the eagle, 

 whale, and elephant downwards, to the monads and 

 vibriosi of infusorial life. Eecently even the bottom 

 of the sea, at the depth of two miles, has been found 

 laden with these forms of life, perfect in their indivi- 

 duality, and not inferior in type to the kindred species 

 existing above. The enumeration of animal species, so 

 denominated, reaches at least 200,000, arid is every 

 day augmenting. But this gives a feeble idea of those 



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