34 Living and Dead Matter and 



or even from one solar system to another. If it be 

 true that there is no spontaneous generation; if it be 

 true that all cells are potentially immortal, we may 

 indeed seriously raise the question: May not life after 

 all be eternal ? Such ideas were advocated by Richter 

 in a rather phantastic way and more definitely by 

 Helmholtz as well as Kelvin. The latter authors 

 assumed that in the collision of planets or worlds on 

 which there is life, fragments containing living organ- 

 isms will be torn off and these fragments will move as 

 seed-bearing stones through space. "If at the present 

 instant no life existed upon this earth, one such stone 

 falling upon it might . . . lead to its becoming covered 

 with vegetation." Arrhenius points out the difficulties 

 which oppose such a view, as, e. g., the fact "that the 

 meteorite in its fall towards the earth becomes incan- 

 descent all over its surface and any seeds on it would 

 therefore be deprived of their germinating power." 



Arrhenius suggests another and much more ingenious 

 idea based on the fact that for particles below a certain 

 size the mechanical pressure produced by light waves — • 

 the radiation pressure — can overcome the attractive 

 force of gravitation. 



Bodies which according to Schwarzschild would undergo 

 the strongest influence of solar radiation must have a dia- 

 meter of 0.00016 mm. supposing them to be spherical. The 

 first question is therefore: Are there any living seeds of 

 such extraordinary minuteness' The reply of the botanist 



