268 THE THEORIES OF EVOLUTION 



ganism can be a purely local one. His theory of 

 character transmission endeavours to explain not only 

 the influence of an external factor on the reproductive 

 elements, but also the reappearance in the offspring 

 of modifications identical with those observed in the 

 parent. 



"Natural phenomena group themselves," he says, 

 "in parallel series of different scales of magnitude." 

 For instance, we can distinguish within one series 

 among sound vibrations, light vibrations and another 

 type of motion observed in a very different form — 

 the periodicity of planetary revolutions. In another 

 order of phenomena which present a direct interest in 

 the study of life we can also distinguish several struc- 

 tural series. There are first of all the atoms, the seat 

 of chemical phenomena, "which are therefore of the 

 scale of magnitude of the atoms or at least of the dis- 

 tance which separates the atoms within the molecules 

 or the molecules themselves." Then comes the col- 

 loidal structure which offers a special interest for biol- 

 ogists as the living substance presents that very struc- 

 ture; colloidal particles are much larger than chemical 

 molecules of which they contain a large number; 

 "chemistry deals with atomic dimensions ; the colloidal 

 state on the contrary is the seat of activities whose 

 scale of magnitude is larger than that of molecular 

 reactions." Biological phenomena, which involve 

 chemical phenomena "take place along two different 



