98 WHAT IS LIFE 



to be definitely known; but how the nucleus is built 

 up, that is, the manner and pattern of the com- 

 bination of the constituents of the nucleus, is not 

 yet known. Radioactivity gives glimpses. Aston 

 considers it "evident" that "the nuclei of even light 

 elements are very complex structures. "^^ Whatever 

 the manner of the combination, the enormous 

 energy that is displayed in radioactivity is locked up 

 in the nucleus. 



Some hold that the nucleus is built up of hydro- 

 gen and helium atoms. 



Nuclei vary greatly in their stability. 



The close packing of the constituents of the 

 nucleus as compared with the loose structure of 

 the atom, is certain; since the minuteness of the 

 nucleus of the atom as compared with the volume 

 of the atom, has been established. 



The impenetrability of the nucleus has been shown. 



The relationship (not the periodicity itself) of 

 properties of the atoms that has led to the classifi- 

 cations of the periodic table of the elements, and the 

 fact that the elements form a series that progresses 

 arithmetically from hydrogen, atomic number 1, to 

 uranium, atomic number 92, indicate relationship of 

 pattern, or the same general manner of combination 

 of the constituents for all nuclei. 



" Isotopes, second edition, 124. 



