194 THE FITNESS OF THE ENVIRONMENT 



This is the sufficient practical ground for pre- 

 serving organic chemistry as a separate sci- 

 ence. The subject is so vast that in fact it 

 is impossible to incorporate it with other 

 departments of chemistry. Even the com- 

 pounds of carbon and hydrogen alone are 

 counted by hundreds, those of carbon, hydro- 

 gen, and oxygen, by thousands, and the 

 number of possible compounds of the three 

 elements is almost unlimited. 



The mere number of organic compounds is, 

 however, far from constituting the only dis- 

 tinction between the two departments of 

 descriptive chemistry. The unique variety 

 of compounds containing carbon, hydrogen, 

 and oxygen, and, in a small proportion of cases 

 a few other elements besides, must obviously 

 rest upon the nature of the elements them- 

 selves, especially of course upon the nature of 

 carbon, upon the properties which are pe- 

 culiar to them and which mark them off from 

 other elements, just as the properties of 

 argon, of the metals of the alkalies, or of the 

 halogens determine their own chemical be- 

 havior. Moreover, such characteristics must 

 and do contribute properties to the com- 

 pounds of carbon which are theirs as a class, 

 which distinguish them from the compounds 

 of other elements in somewhat the same way 



