HOW LIFE CAME TO EARTH 175 



to the upper strata of an atmosphere, and here 

 come under the influence of radiant energy of 

 various forms, as minute dust particles may 

 in the aurora borealis, for example. It has 

 been shown that there is a pressure of the 

 light waves upon such particles, which is 

 capable of giving them a translatory velocity 

 in a vacuum, similar to that of the vanes of 

 Crookes' radiometer in radiant light or heat. 

 It is only necessary to assume small enough 

 dimensions of the germ particles to achieve 

 enormous velocities. Arrhenius calculates, 

 that if living germs were carried through the 

 ether by such radiant forms of energy, the 

 time of transit from our earth to Mars would 

 only be twenty days, and from our solar 

 system to the nearest stellar system about 

 nine thousand years. 



These stellar and interstellar hypotheses 

 as to the advent of life upon our earth cannot 

 be better criticized than in the words used 

 by Professor Schafer in his presidential 

 address to the British Association, Dundee, 

 1912 : — " But the acceptance of such theories 

 of the arrival of life on the earth does not 

 bring us any nearer to a conception of its 

 actual mode of origin; on the contrary, it 

 merely serves to banish the investigation of 

 the question to some conveniently inaccessible 



