72 INORGANIC EVOLUTION. [CHAP VI I. 



We may take for granted that as time goes on new intermediate 

 genera will have to be established; the proposed classification lends 

 itself conveniently to this, as there are no numerical relations to be 

 disturbed. 



A still more general chemical classification is the following, it being. 

 understood that in it only the most predominant chemical features are 

 considered, and that there is no sharp line of separation between these 

 larger groups. The peculiar position of calcium and magnesium renders- 

 this caveat the more necessary. 



CLASSIFICATION OF STARS. 

 Highest temperature. 



Gaseous stars 



r Proto-hydrogen stars . . . ( ^rgoman. 

 J I Almtamian. 



f Crucian. 



* Cleveite-gas stars < 



I Taunan. 



. TEigelian. 



Proto-metallic stars 1 Cygnian 



Metallic stars fPolarian. 



I Aldebarian. 

 Stars with fluted spectra Antarian. 



Lowest temperature. 



Achernian. 



Algolian. 



Markabian. 



Sirian. 

 Procyonian. 

 Arcturian. 

 Piscian. 



The detailed chemical facts to be gathered from the definitions of 

 the several genera indicate many important differences between the 

 order of appearance of the chemical substances in the atmospheres of the 

 stars and that suggested by the hypothetical " periodic law." I shall 

 refer to this point later on. 



