40 HUMAN BIOLOGY 



planets of other solar systems far distant in space, arriving 

 as meteors, set free in the earth's atmosphere the organisms 

 they carried from their original home, and that thus terres- 

 trial hfe began. This theory involved difficulties which 

 denied a general acceptance of it. Life in organisms, meteor- 

 borne, would have to be maintained for an impossible 

 length of time, for a meteor derived from the nearest solar 

 system, that of which a Centauri is probably the sun, 

 would require 62,000,000 years to reach the earth, moving 

 at the rate of 40 miles per hour (Arrhenius), and when it 

 plunged into the earth's atmosphere the heat thereby 

 developed would sterihze all organisms on it, even if they 

 survived ahve after so incredibly long a time. 



This theory, which failed to win acceptance, was again 

 advanced, but with an important modification, in 1903 by 

 Arrhenius, who used the then recently discovered fact of the 

 pressure exercised by hght and other radiations to maintain 

 that organisms could be driven by it through space inde- 

 pendently of meteors and with a velocity enormously 

 greater than the latter are supposed to have. This pressure 

 would, according to the calculations of Arrhenius, reduce 

 the time for the transportation of organisms from a Centauri 

 from 62,000,000 years to 9000 years. These would experience 

 a temperature of — 220°c., that of interstellar space, from 

 the beginning to the end of their course, but the low tem- 

 perature, which would reduce desiccation almost to an 

 absolute minimum, would also very greatly reduce the chem- 

 ical activities in the organisms and these would then survive, 

 as it were in a latent condition, and reach the earth's atmos- 

 phere, in which, because of their enormous velocity (more 

 than 800 miles per second) friction would develop a tem- 

 perature of not less than ioo°c. This, Arrhenius held, 

 would not necessarily sterilize them for the protein in them, 

 being in a very dry state, would not be denatured at such a 

 temperature. He discounted the action of light on such 

 organisms, for cultures of certain bacteria had been found 

 unaffected by bright sunlight after a month of exposure 

 to it. 



This theory, in the present state of our knowledge bearing 

 on the facts involved, does not appear tenable. It is 



