80 HEREDITY AND SELECTION IN SOCIOLOGY 



mission is excluded owing to the sterility of the caste. This 

 alone suffices to show that the LamarcMan hypothesis of the 

 hereditary transmission of modifications arising from use or dis- 

 use is wholly insufficient — if, indeed, it be applicable at all — to 

 explain the phenomena of organic evolution. Another instruc- 

 tive example of the insufficiency of the Lamarckian theory is 

 also furnished by the ant. The institution of slavery in certain 

 species, and the development of a race of worker ants, can only 

 have taken place after the collective life in society had long 

 been established among these remarkable animals. But by this 

 time the worker ants were sterile ; and just as the absence of 

 wings and the regression of the ovaries show that structural 

 variations have been established after the sterility of the working 

 ants sets in, so these profound modifications of the social hfe 

 show that variations of instinct can likewise occur. 



An argument frequently urged against the critics of the 

 Lamarckian theory, and which Herbert Spencer was the first to 

 bring forward, is that based on coadaptation. It is argued that 

 the correlated variation of the difEerent component parts of an 

 organ, or the correlated variation of different parts of the 

 organism itself, in response to a primary variation of a single 

 part, shows that natural selection is insufficient as an explana- 

 tion of the phenomena of adaptation. For instance, the develop- 

 ment of the antlers of the Irish stag entails a correlated develop- 

 ment of the skull, of the neck, of the muscles in the neck and 

 back, of the bones and muscles of the legs, and of the nerves 

 attendant on the muscles. This harmonious development of 

 difEerent parts of the organism cannot, it is maintained, be due 

 solely to natural selection. 



In the first place, it must be noted that the extraordinary 

 development of the antlers of the Irish stag was not the work 

 of a few generations, but of many. Many generations must 

 have come and gone before those antlers attained to the pro- 

 portions which they finally possessed. But if time was necessary 



