EXPERIMENTAL CHECKS 



51 



on earth through natural causes form the subject of intense scientific 

 studies, it seems better to drop altogether the term of generatio 

 spontanea. 



EXPERIMENTAL CHECKS 



The theoretical importance of the shorter ultraviolet rays of the sun- 

 light, those with a wavelength below 1850 A, for photosynthetic 

 inorganic processes from simple stable gases such as CO, CH4, H2O 

 and NHs, is illustrated in Fig. 8, taken from the recent review of 

 Terenin (1959). The result of experimental studies of the regions of 

 adsorption, at which photochemical activity may take place of just 

 those gases from which a primeval atmosphere might be formed, 

 and which would form the buildingstones of any primary 'organic' 

 molecules, show that these coincide with that of free oxygen, its 

 dissociation products and ozone. Consequently, the present atmos- 

 phere is opaque to light of such short wavelengths, which is absorbed 

 by the ozone high up in the atmosphere. Hydrogen, on the other 

 hand, is quite transparent for light of this wavelength. So in an 

 atmosphere composed principally of hydrogen, these rays of sunlight 



Fig. 9. Diagram of spark-discharge apparatus, used to produce or- 

 ganic' compounds from hydrogen, methane, ammonia and water in an 

 anoxygenic environment (from S.L.Miller, 1959). 



