54 ETERNITY OF LIFE 



perfectly possible that germs might pass through the atmo- 

 sphere without losing their viability. 



Similar views were put forward in Britain by Lord Kelvin,^ 

 who wrote in 1871 : 



Should the time when this Earth comes into collision with 

 another body, comparable in dimensions to itself, be when it is 

 still clothed, as at present, with vegetation, many great and 

 small fragments carrying seed and living plants and animals 

 would undoubtedly be scattered through space. Hence and 

 because we all confidently believe that there are at present, 

 and have been from time immemorial, many worlds of life 

 besides our own, we must regard it as probable in the highest 

 degree that there are countless seed-bearing meteoric stones 

 moving about through space. 



These statements made a very great impression on the 

 scientists of those times. In Germany they were supported 

 by H. Helmholtz,^" who considered that the germs of life 

 had reached the Earth by means of meteorites which, in 

 their passage through the atmosphere of the Earth, had been 

 strongly heated on the surface only, while the inner part 

 remained cool. In France this opinion was shared by van 

 Tieghem, who wrote that the Earth received the seeds of life 

 by their being carried on meteorites ; henceforth it con- 

 served the life which was derived from these original germs. 



The main foundation for all these hypotheses was the 

 fact that many rocky meteorites contain compounds of 

 carbon approaching hydrocarbons in their composition. For 

 example, chemical analyses by Cloez'^ of the Orgeuil meteor- 

 ite revealed the presence of amorphous substances very simi- 

 lar to the humus-like substances found in some fuels dug 

 from the earth. At the time when the presence of hydro- 

 carbons in meteorites was first discovered people were still 

 convinced that organic substances, including hydrocarbons, 

 could only be formed under natural conditions in living 

 cells. Many scientists therefore supposed that the hydro- 

 carbons found in the meteorites had been formed there 

 secondarily as the result of the decomposition of organisms 

 which had lived at some time on these heavenly bodies. This 

 raised the question of the possible existence of living bacteria 

 or their spores inside the meteorites. 



