Nos. 622-023] MIGRATION A FACTOR IN EVOLUTION 481 



climax habitat is an increasing and ascending one. _ . That the domi- 



fairly established because diverse local original conditions are trans- 

 formed into the climax or dominant type. 



To students of human economics (for except ecolo- 

 gists we seem to have almost no students of general eco- 

 nomics, including wild animals and plants) Bancroft's 

 law should be a revelation. The interference or friction 

 seen in economics (Conant, '08) should be included under 

 Bancroft's law. That these laws apply to human social 

 conditions as well can easily be tested by any one who 

 will venture to " interfere" with any system of social 

 machinery, whether it be of the family, fashion, church, 

 state or a political party, for very soon the pressure or 

 stress exerted by the " system" will make itself evident, 

 by the processes of coercion, persuasion, ridicule, pros- 

 elyting, threat, ostracism, or by a final crushing effort ; 

 for interference with a dominant system whether it is 

 large or small has but one tendency. Years ago Bagehot 

 ('73, p. 97) clearly recognized what appears to be essen- 

 tially the laws mentioned above, and applied them with 

 great skill to the development of political history, under 

 the names of "persecution" and ''imitation." Perse- 

 cution corresponding to interference and imitation to ac- 

 celeration. Hooker ('17, p. 208) not recognizing Ban- 

 croft's law, suggests what he calls the "principle of inte- 

 gration" to cover the interaction of the systems which he 

 recognizes. He says: "These systems are invariably 

 overcoming the effects of limiting factors." 



(d) Interaction of Systems. — The next higher category, 

 above the animal system, is the interaction of the systems, 

 and their principles of complex action. To be sure, the 

 animal system can not be divorced from its environment, 

 so that several important features of this interrelation 

 have already been discussed briefly. In dealing with the 

 organism and the environment these two gross systems 

 are perhaps the most clearly recognized in biology. The 



