







192 



SELECTION 



Chap. XX. 



• 



CHAPTER XX. 





SELECTION BY MAN. 



SELECTION A DIFFICULT ART — METHODICAL, UNCONSCIOUS, AND NATURAL SELECTION 



•RESULTS OF METHODICAL SELECTION — CARE TAKEN IN SELECTION — SELECTION 

 WITH PLANTS — SELECTION CARRIED ON BY THE ANCIENTS, AND BY SEMI-CIVILISED 

 PEOPLE — UNIMPORTANT CHARACTERS OFTEN ATTENDED TO — UNCONSCIOUS SELEC- 

 TI0N — AS CIRCUMSTANCES SLOWLY CHANGE, SO HAVE OUR DOMESTICATED ANIMALS 

 CHANGED THROUGH THE ACTION OF UNCONSCIOUS SELECTION — INFLUENCE OF 

 DIFFERENT BREEDERS ON THE SAME SUB-VARIETY — PLANTS AS AFFECTED BY 

 UNCONSCIOUS SELECTION — EFFECTS OF SELECTION AS SHOWN BY THE GREAT 

 AMOUNT OF DDJFERENCE IN THE PARTS MOST VALUED BY MAN. 



The power of Selection, whether exercised by man, or brought 

 into play under nature through the struggle for existence and 

 the consequent survival of the fittest, absolutely depends on the 

 variability of organic beings. Without variability nothing can be 

 effected ; slight individual differences, however, suffice for the 

 work, and are probably the sole differences which are effective 

 in the production of new species. Hence our discussion on the 

 causes and laws of variability ought in strict order to have pre- 

 ceded our present subject, as well as the previous subjects of 

 inheritance, crossing, &c. ; but practically the present arrange- 

 ment has been found the most convenient. Man does not 

 attempt to cause variability ; though he unintentionally effects 

 this by exposing organisms to new conditions of life, and by 

 crossing breeds already formed. But variability being granted, 

 he works wonders. Unless some degree of selection be exercised, 

 the free commingling of the individuals of the same variety soon 

 obliterates, as we have previously seen, the slight differences 

 which may arise, and gives to the whole body of individuals 

 uniformity of character. In separated districts, long-continued 

 exposure to different conditions of life may perhaps produce new 

 races without the aid of selection ; but to this difficult subject 



