WHAT IS PHYSICAL LIFE 



tions, and to illustrate these by the prod- 

 ucts of selection by human breeders. But 

 when the search for the secret of all phy- 

 sical life led first to a microscopic cell, and 

 then to a much smaller body in the cell 

 called its nucleus, and then to far minuter 

 things in the nucleus called the chromatin 

 rods, the whole question of natural selec- 

 tion, along with many other like questions, 

 seemed in danger of being lost both to 

 sight and to conception. 



But the original Darwinians were soon 

 to experience another severe strain. Pro- 

 fessor August Weismann, the eminent bi- 

 ologist of the University of Freiburg, an- 

 nounced as the result of his observations 

 that no physical change occurring in the 

 body of either a plant or animal during 

 its lifetime can be transmitted to its 

 descendants. 



To an ordinary mind this assertion 

 seems ruinous to the whole Darwinian 

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