46 THE FOUR SEGREGATIVE PRINCIPLES. 



tions in the same direction)/'* which are gradually accumulated by 

 selection. Another point presented by the same writers is the conti- 

 nuity of tradition, secured by training, suggestion, and example on 

 the part of the parents and imitation on the part of the young. The 

 effects of tradition have also been very clearly illustrated by F. W. 

 Headley in his recent book.f I quote a few sentences in which he 

 summarizes the effects of accommodation and tradition : 



The result is that among the higher plastic classes of animals evolution proceeds 

 more rapidly. But obviously the quickening up of evolution is not all. The 

 individual gains in importance. He improves his powers, is able to face a change 

 of environment that otherwise would have been fatal. He makes an environment 

 for his young in which intelligence can be developed ; he chooses the environment 

 which they shall have when out of the nursery, and so decides to some extent what 

 qualities shall be the winning qualities in life. In fact, he is beginning to take the 

 helm and steer the species. Or we may put it in this way: When the individuals 

 of one generation decide the environment in which the next shall grow up, selec- 

 tion ceases to be purely natural; it is in, part artificial. J 



These quotations are sufficient to show that there is increasing 

 recognition of the fact that there may be changes in the organism 

 that are not dependent on changes in the environment, and are there- 

 fore not dependent on change in the form of the natural selection. In 

 choosing terms for designating these processes I think we should care- 

 fully follow Professor Baldwin's suggestion "that selection in the 

 Darwinian sense should be used only when the essential conditions 

 of organic progress by survival are present, namely, variations and 

 physical heredity."? 



In my own usage, selection has been applied only to processes secur- 

 ing the survival of part of the variations of a race or species with the 

 exclusion of other variations, and so influencing its powers of heredity ; 

 and isolation has been limited to the prevention of free crossing be- 

 tween co-existing groups. In order to do this, and at the same time 

 clearly present the principles controlling the evolution of habitudes, it 

 has been necessary to find two terms that might hold the same rela- 

 tion to innovation and tradition that selection and isolation hold to 

 variation and heredity. The best words I have found are election 



* See letter from J. Mark Baldwin in Nature for April 15, 1897, also the same in 

 Science for April 23, 1897, on "Organic Selection." In this letter will be found 

 references to discussion on the subject during the previous year in various books 

 and journals. 



f Problems of Evolution, pp. 120-128. London, Buckworth & Co., 1900, and 

 New York, Crowell & Co., 1901. 



J Problems of Evolution, p. 128. 



See Science May 8, 1 898. The same limitation is also advocated in his Social 

 and Ethical Interpretations, Appendix B. 



