248 THE ORIGIN OF LIFE 



in the structure or chemical composition of the 

 body when exposed to the influence of the exciting 

 light, the new luminosity and the new absorption 

 being due to these new free periods. 



The more refrangible or exciting rays form un- 

 stable molecular aggregates, and it is in the 

 breaking down of these unstable and probably 

 large molecular groups that the luminosity occurs. 

 Thus, as we have said, as in the case of photo- 

 graphy a chemical change appears to be produced 

 by the blue and violet and ultra-violet rays, but one 

 that differs from this from the physical point of view 

 in so far as the molecular aggregations, instead of 

 remaining fixed, rapidly disintegrate, radiating in- 

 tensely all the while the energy which was stored 

 up in their formation. And the luminosity itself 

 is thus but the visible manifestation of the 

 process of building up and breaking down of 

 complicated molecular aggregations : a process 

 analogous to metabolism, however much it may 

 in reality diifer from it. Our anticipation of the 

 previous chapters is thus beginning to unfold 

 itself. 



On my other hypothesis the vibrations which 

 give rise to the fluorescent light would not be 

 harmonic ones if the absorption were to depend 

 upon the intensity of the fluorescent light. 



An elementary knowledge of the subject will 

 enable us to comprehend that the absorption in 

 such a vibration must be independent of the 

 amplitudes. But if new periods are excited as I 



