ARTIFICIAL SELECTION 



SI 



duced in artificial selection are not those which could arise 

 or even exist in nature. In nature, hardiness or power of 

 resistance in competition or the struggle for existence is all 

 important. In artificial selection stress is laid chiefly on char- 

 acters useful or attractive to man. From the standj^oint of 

 self dependence, the improvements due to artificial selection 

 constitute a sort of retrogression. 



In general, the production of a new race of animals or plants 

 in domestication is the 

 outcome of the work of 

 a number of factors, in 

 which human or artificial 

 selection plays a leading 

 part, a part which in- 

 creases in importance 

 with the degree of intel- 

 ligent choice concerned 

 in it. 



In the formation of 

 a new race of animals or 

 plants, we may have the 

 following stages or fact- 

 ors: 



1. Unconscious se- 

 lection with more or less 

 complete isolation. 



2. Conscious selec- 

 tion of the most desira- 

 ble individuals. 



3. Conscious selec- 

 tion directed toward 

 definite or special ends. 



4. Crossing with other races or with other species (known 

 as hybridizing), in order to increase the range of variation, or 

 to add or combine certain specific desirable qualities or to elimi- 

 nate those undesirable, this accompanied by conscious selection 

 directed toward definite ends. On this series of processes 

 breeding as a fine art must depend. 



Taking as an illustration some of the breeds of medium 

 wool sheep found in Southern England: we have (1) the domes- 

 tication of sheep in each of the different counties or natural 



Fig. 46. — ^White-crested black Polish cock. 

 (After photograph.) 



