THE BEGINNINGS OF LIFE 



istic doctrine of Stahl has been replaced. In- 

 stead of a difference in kind between life and 

 not-life, we get only a difference of degree ; so 

 that it again becomes credible that, under favour- 

 ing circumstances, not-life may become life. 



In the next place the overthrow of the dogma 

 of fixity of species, and the consequent general 

 displacement of the Doctrine of Creation by the 

 Doctrine of Evolution, have made the scientific 

 world familiar with the conception of the de- 

 velopment of the more specialized forms of life 

 from less specialized forms ; and thus the de- 

 velopment of the least specialized forms of life 

 from the most complex forms of not-life ceases 

 to seem absurd, and even acquires a sort of pro- 

 bability. And finally, the researches of geolo- 

 gists, showing that our earth's surface was once 

 " melted with fervent heat," and confirming the 

 theory of the nebular origin of our planet, have 

 rendered it indisputable that there must once 

 have been a time when there was no life upon 

 the earth ; so that certainly at some time or 

 other, though doubtless not by a single step but 

 by a number of steps, the transition from not- 

 life to life must have been made. Hence the 

 doctrine omne vivum ex vivo, as now held, means 

 neither more nor less than that every assem- 

 blage of organic phenomena must have had as 

 its immediate antecedent some other assemblage 

 of phenomena capable of giving rise to it ; in 

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