234 RE 7. J. T. GTJLICK ON DIYEROENT EVOLTJTION 



CHAPTEE lY. 

 Description and Classification of the Causes of 



CUMULATIYE SEGREGATION (continued). 



B. Eeflexiye Segregation. 



Eeflexive Segregation is Segregation arising from the relations 

 in which the members of one species stand to each other. 



It includes three classes, which I call ConjuDctional, Impreg- 

 national, and Institutional Segregation. 



It is important to observe that Intergeneration requires com- 

 patibility in all the circle of relations in which the organism 

 stands ; but, in order to ensure Segeneration between any two 

 or more sections of a species, it is sufficient that incompati- 

 bility should exist at but one point. If either sexual or social 

 instincts do not accord, if structural or dimensional characters 

 are not correlated, if the sexual elements are not mutually 

 potential, or if fixed institutions hold groups apart, Intergen- 

 eration is prevented, and Segeneration is the result, either as 

 Segregation, or as Separation that is gradually transformed 

 into Segregation. 



{a) Conjunctional Segregation. 



Conjunctional Segregation is Segregation arising from the 

 instincts by which organisms seek each other and hold together 

 in more or less compact communities, or from the powers of 

 growth and segmentation in connection with self-fertilization, 

 through which similar results are gained. 



I distinguish four forms — Social, Sexual, Germinal, and Floral 

 Segregation. 



10. Social Segregation is produced by the discriminative action 

 of social instincts. 



The law of social instinct is preference for that which is 

 familiar in one's companions ; and, as in most cases the greatest 

 familiarity is gained with those that are near of kin, it tends to 

 produce breeding within the clan, which is a form of Segregate 

 Breeding. If the clan never grows beyond the powers of 

 individual recognition, or if the numbers never become so great 

 as to impede each other in gaining sustenance, there will be but 

 little occasion for segregation ; but multiplication will lead to 

 segmentation. Wherever the members of a species, ranging freely 



