210 THE FITNESS OF THE ENVIRONMENT 



<-C=>. Next comes the fact that carbon 

 atoms, when otherwise exclusively in com- 

 bination with hydrogen, and under other 

 circumstances in lesser degree, possess an 

 almost unlimited capacity to join together 

 and form chains and rings in great variety. 

 The longest carbon chain yet synthesized oc- 

 curs in the compound hexakontane, 1 C 60 H 12 2, 

 a substance whose constitution is probably as 

 follows : — 



CH 3 CH 2 CH 2 : CH 2 -CHs-CHa. 



(CH 2 ) 5 4 



The stability of this substance justifies a 

 belief that even far longer chains of carbon 

 atoms can exist, and, in fact, there is no known 

 limit to the possibility of stringing carbon 

 atoms together. 



No other element is believed to share both 

 of these characteristics, and there are various 

 reasons to suppose that the resulting pecul- 

 iarity of the system of organic compounds 

 is really unique. Turning to the periodic 

 classification of the elements, it will be seen 

 that carbon is a member of the first series. 

 Several of the elements of this series, unlike 

 all the other elements except hydrogen, pos- 

 sess very definite individual properties, which 



1 " Hell und Hagele," Berichte, 22, 502 (1899). 



