224 RET. J. T. GULICK ON DIYERGENT EVOLUTION 



that succeed in germinating in contrasted situations, the difference 

 is directly due to a Diversity in the forms of ISTatural Selection 

 affecting the seed, and the Separation is what I hereafter describe 

 as Local Separation passing into Local Segregation. We there- 

 fore see that what I liere call Industrial Segregation depends on 

 psychological powers acting in aid of divergent physiological 

 adaptations to the environment, or in aid of adaptations that are 

 put to different uses. 



Observation shows that there is a multitude of cases in which 

 Endeavour according to Endowment brings together those simi- 

 larly endowed and causes them to breed together ; and when the 

 species is thus divided into two or more groups somewhat differ- 

 ently endowed, there will certainly be an increased divergence in 

 the offsp)ring of the parents thus Segregated ; and so on in each 

 successive generation, as long as the individuals find their places 

 according to their endowments, and thus propagate with those 

 similarly endowed, there will be accumulated divergence in the 

 next generation. Indeed it is evident that Endeavour according 

 to Endowment may produce under one environment what Natural 

 Selection produces when aided by local separation in different 

 environments. As it produces the separate breeding of a diver- 

 gent form without involving the destruction of contrasted forms, 

 it is often the direct cause of divergent transformations ; while 

 Natural Selection, which results in the separate breeding of the 

 fitted through the failure of the unfitted, can never be the cause 

 of divergence, unless there are concurrent causes that produce 

 both divergent forms of Natural Selection, and the separate 

 breeding of the different kinds of variations thus selected. 



Suetudinal Intension, — Another law is usually believed to be 

 connected with Endeavour which, if it exists, must conspire to 

 enhance its tendency to produce divergent evolution. I refer 

 to the influence which the habitual endeavour of the parents has 

 on the inherited powers of the offspring. We may call it the 

 law of Endowment of Offspring according to the Exercise or 

 Endeavour of Parents, or more briefly Suetudinal Intension. 

 The inherited eftects of use and disuse have been fully recognized 

 by Darwin, Spencer, Cope, Murphy, and others, and need not 

 here be discussed. The one point to which I wish to call atten- 

 tion is, that in order that diversity of use should produce diver- 

 gent evolution, it is necessary that free crossing should be pre- 

 vented between the different sections of the species in which the 



