314 BEV. J. T. GT7LI0K ON 



Eight Pkinciples of Monottpic Evolution. 

 Let us uow cousider how this initial Segregation, which is 

 always present where migration or geological subsidence produces 

 indiscriminate Separation, is enhanced and intensified by the 

 cooperation of other principles, and how forms, segregated through 

 possessing different characters in some one respect, come to 

 diverge in' other respects. For example, when differences of 

 colour become the occasion for sexual and social Segregation, how 

 does this open the way for divergent transformation in habits of 

 feeding and in a thousand other respects ? The principles co- 

 operating with Independent Generation in producing this en- 

 hanced divergence are all causes of simple transformation, or 

 monotypic evolution when there is free intergeueration. Diver- 

 gent breeds of domestic animals have always been produced when 

 the different sections of a species in the care of different races of 

 men have been prevented from interbreeding, thus securing their 

 Independent Transformation during the process of domestication. 

 So in nature, when any form of Independent Greneration has been 

 established, any cause of transformation that may afterwards 

 arise will always produce more or less divergent evolution, and 

 never that which is in every respect parallel. But we must 

 defer the discussion of this subject till we have enumerated the 

 more manifest of the principles of monobypic evolution : — 



1. Assimilational Transformation, or modification due to defi- 

 ciency with economy, or redundance with profusion, of growth, 

 resulting from different degrees of assimilative power, " Eco- 

 nomy of growth " is a term already in use, but a term is needed 

 that shall include both this and its opposite. 



2. Stwiulational Transformation, or modification produced by 

 changed motions in the fluids of an organism responsive to 

 changed molecular influences in the enyironment. Under this 

 principle we may place the direct influences of light, heat, elec- 

 tricity, the dampness of the air or the saltness of the water in 

 which the organism is bathed, the quality of the food, and all 

 stimulation from physical and chemical causes, exclusive of those 

 resulting in muscular activity or the movement of organs. 



3. Suetudinal Transformation, or modification due to the effects 

 of use, disuse, and habitual effort in producing motions, and in 

 resisting the strain of gravity and other forces tending to produce 

 motion. Suetude is not found in the dictionary, but I venture 



