48 DARWINISM STATED BY DARWIN HIMSELF. 



of improving the breed, by preserving in each successive 

 generation the individuals which he prizes most, and 

 by destroying the worthless individuals, slowly, though 

 surely, induces great changes. As the will of man thus 

 comes into play, we can understand how it is that do- 

 mesticated breeds show adaptation to his wants and pleas- 

 ures. We can further understand how it is that domestic 

 races of animals and cultivated races of plants often ex- 

 hibit an abnormal character, as compared with natural 

 species ; for they have been modified not for their own 

 benefit, but for that of man. 



INHEKITED EFFECT OF CHANGED HABITS. 



Origin of When we compare the individuals of the 



Species, page same variety or sub variety of our older culti- 

 5 * vated plants and animals, one of the first points 



which strikes us is, that they generally differ more from 

 each other than do the individuals of any one species or 

 variety in a state of nature. And if we reflect on the 

 vast diversity of the plants and animals which have been 

 cultivated, and which have varied during all ages under 

 the most different climates and treatment, we are driven to 

 conclude that this great variability is due to our domestic 

 productions having been raised under conditions of life 

 not so uniform as, and somewhat different from, those to 

 which the parent species had been exposed under nature. 



Changed habits produce an inherited effect, 

 as in the period of the flowering of plants 

 when transported from one climate to another. With 

 animals the increased use or disuse of parts has had a 

 more marked influence ; thus I find in the domestic duck 

 that the bones of the wing weigh less and the bones of 

 the leg more, in proportion to the whole skeleton, than 



