CHAPTER XIV 



THE ORIGIN OF LIFE " NATURA NON 



FECIT SALTUM " 



It cannot, thus, be held that between living beings 

 and dead matter there is a great gulf fixed. Both 

 are made of the same urstoff \ both are responsive 

 to external stimuli, and both participate in activities 

 commonly called vital. 



Still, between the living and the dead there is a 

 difference. Plants and animals reproduce their 

 kind ; plants and animals assimilate, i.e. change 

 other substances into the substances of their 

 tissues ; and this is the case even in the very lowest 

 forms of vegetable and animal life. There is 

 another difference too — a difference of the greatest 

 importance — plants and animals, in the twinkling 

 of an eye, and under a stimulus apparently 

 completely inadequate, completely change their 

 chemical and mechanical characters and become, as 

 we say, dead^ while the chemical and mechanical 

 properties of the inorganic know no such cataclysms. 



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