6o THE IfOUR SEGREGATIVE PRINCIPLES. 



group. This molding of variation and heredity by isolation and selec- 

 tion results in racial segregations. But even plants are endowed with 

 powers that enable each individual to do something toward directly 

 adjusting itself to the environment in which it is placed, for they will 

 stretch their branches and turn their leaves toward the light, and their 

 roots will bend toward moisture and away from hard or irritating 

 substances obstructing their course. This power of the individual 

 for experimental action with ability to persist in the action that secures 

 the best results is called accommodation; and the molding of accom- 

 modation and tradition into habitudes produces habitudinal segrega- 

 tions with their adjustments. We find that accommodation fills a 

 sphere of increasing importance in the evolution of animals according 

 to the degree of their mental endowments. In studying the evolution 

 of the higher animals it is especially necessary to consider the adjust- 

 ments produced through the molding of accommodations by election, 

 as well as those produced by the molding of variations by selection. 

 The importance of prolonged infancy and childhood in mankind has 

 been rightly emphasized by John Fiske; but the significance of this 

 condition is found in its opening the way for the building of habits 

 guided by the experience of many generations. The combined wis- 

 dom of countless ancestors thus is transmitted to the young through 

 language, example, and training, foi^mulated in maxims, and customs, 

 in penalties and rewards, and instilled into minds specially endowed 

 with powers of imitation and with aptitudes for forming lasting habits ; 

 and the process is continued much longer than in the case of animals 

 lower than man. In the case of beasts and birds the equipment for 

 the struggle of life is received in a larger degree through inherited 

 powers and instincts, though tradition is also of importance. 



6. The Two Methods of Adjustment as Applied to New Conditions, Suddenly 

 or Gradually Encountered. 



I have already considered certain cases involving resources that are 

 varied but familiar to the species and easily explored, in which habi- 

 tudes (that is, traditional forms of accommodation), and aptitudes 

 (that is, inherited forms of adaptive variation), become the control- 

 ling factors in determining selection. We wish now to consider cases in 

 which the new environment fails to present the conditions and resources 

 to which the organism has been accustomed. In the first place, if 

 the species has but slight accommodative power, and the new condi- 

 tions are suddenly encountered, habitudes and aptitudes will be of 

 little or no avail in guiding ; and, though some of the variations may 

 be able to battle with the new conditions for a generation or two, none 

 will be able to survive and propagate permanently. 



