THE GENESIS OF LIFE. 169 



or without the existence of pre-existent life, would not in 

 any degree lessen the truth or alter the significance of the 

 fully demonstrated fact that germs borne by the air or 

 contained in fluids constitute the common cause of life- 

 development in putrefying and decomposing solutions. The 

 two theories, as a matter of logical consistency, may coexist ; 

 and should spontaneous generation be ever demonstrated to 

 occur a fact from the clear demonstration of which we 

 appear as yet to be very far removed indeed we shall find 

 the truth of the germ theory to be in no sense impugned. 

 In the absence of definite proof on the other side, the 

 scientific mind will not hesitate to regard biogenesis as 

 an explanation of the genesis of life, of which the great merit 

 consists in its perfect harmony and analogy with the observed 

 laws of living nature. 



It might be imagined that the controversy between these 

 two theories of life-genesis had well-nigh been contested to 

 its furthest limits, and that the motto " Omne vivum ex vivo " 

 might be inscribed over the portals of natural science as 

 expressive of a fundamental article of scientific faith. But 

 a little inquiry shows that of late years the doctrine of 

 abiogenesis has been gaining ground, and that its supporters 

 have been both anxious and willing to join issue with their 

 opponents. The contest, in truth, has not ceased; the 

 battle-field has simply been changed. New aspects of con- 

 troversy have appeared ; and, driven from the consideration 

 of the nature of atmospheric germs, the litigants have girded 

 themselves anew for a contest the issues of which extend to 

 wider and more important spheres of thought than those 

 embraced by the mere question of the existence or non- 

 existence or of the vital powers of germs. Recent science 

 has thus speculated with great persistence regarding the 

 origin of life at large. How did life originate at first on the 

 globe ? Human reason and scientific belief would seem to 

 suggest that life must have had a beginning ; and geological 

 science negatives the idea that the present condition of the 

 earth has been eternal. If, then, we consider that our earth 



