50 THE FOUR SEGREGATIVE PRINCIPLES. 
contact with the problems of evolution, in both realms, to realize that 
great illumination for each will be found in the study of the interac- 
tion between the two realms. Those who are doubtful concerning 
the interaction of the two spheres will gain light from Baldwin’s 
Social and Ethical Interpretations and his Development and Evolu- 
tion, and from the discussions on organic selection given by Osborn, 
Baldwin, and others in Science and The American Naturalist during 
1896-98. <A clear exposition of ‘‘organic selection”’ is also given in 
Conn’s ‘‘Methods of Evolution,’ a work presenting with remarkable 
fairness the results reached by different schools of biologists, and the 
same subject is discussed by Lloyd Morgan in his volume entitled 
‘‘Habit and Instinct,” especially in the last four chapters. 
5. Determinate Evolution of Evolutionary Terminology. 
With gradually advancing clearness, the relations of the two 
spheres of evolution to each other have been recognized, while at the 
same time the necessity for a distinct nomenclature for the processes 
shaping the evolution in each sphere has been increasingly realized 
and in some degree provided for. On the one hand variation, hered- 
ity, and adaptation have been restricted in their application to pro- 
cesses and powers by which racial characters are produced, and on 
the other hand the correlative terms “ innovation,’’* ‘‘tradition,’’+ and 
‘accommodation ’’t have been introduced to designate analogous pro- 
cesses by which acquired characters are produced. There remains, 
however, much confusion due to attempts to extend the scope of the 
term ‘‘ selection ’’ so as to include the processes by which social habits 
and customs are established; and sometimes even to designate pro- 
cesses that properly come under the term ‘‘isolation.”” I believe the 
only remedy will be found in the introduction of two terms that shall 
take the place in the theory of the evolution of habitudes that isola- 
tion and selection fill in the theory of the evolution of aptitudes. The 
advance toward this end is, I believe,an evolution that can not be 
stayed. What terms will eventually prevail is a matter of less cer- 
tainty and of less importance. 
The scheme presented in this chapter is offered by way of sugges- 
tion and with the hope that it may lead to suggestions from others, 
and thus help in the attainment of a completer theory and better 
nomenclature than any now in use. As has been said by Prof. E. O. 
Whitman, ‘‘Cross-fertilization works rejuvenation in theories as in 
organisms.” 
* See Tarde’s Social Laws, pp. 40, 52. 
{ See Baldwin’s Development and Evolution, p. 152. 
t [btd., p. 151. 
