NUCLEUS AS SOURCE OF ENERGY 171 



recent work, to be merely the more stable survivals 

 of aggregates of electrons of which all matter is 

 composed, and to be the inert products of unstable 

 radio-active bodies which differ from them only in 

 being more complicated, so, too, does it appear that 

 the elementary substance to which life is due is 

 largely the result of a peculiar combination of 

 electrons, vastly more complicated than anything 

 which inorganic matter at the present day may have 

 to show us. We have explained, or tried to explain, 

 how the union of an inorganic substance with organic 

 compounds can give rise to active and structural 

 forms. The manner in which the descent of such 

 types may have taken place is what we have to deal 

 with in what follows. 



