SELECTION EVOLUTION 



231 



of characteristics from parent to offspring is heredity. 

 By " selecting the best " for seed the farmer maintains and 

 improves his crops. 

 It is said that "like 

 produces like." This 

 is true of the general 

 or average features, 

 but we have seen that 

 the reproduction is 

 not exact. It is truer 

 to say that similar 

 produces similar. 

 Fig. 384 represents a 

 marked case of he- 

 redity of special char- 

 acters. The plants on 

 the right grew from a 

 parent 24 in. high and 

 30 in. broad. Those on the left grew from one 12 in. high 

 and 9 in. broad. (For a history of these parents see 

 "Survival of the Unlike," p. 261.) 



378. SELECTION. There is intense struggle for existence: 

 there is universal variation : those variations or kinds live 

 which are best fitted to live under the particular condi- 

 tions. This persistence of the best adapted and loss of the 

 least adapted is the process designated by Darwin's phrase 

 "natural selection" and by Spencer's "survival of the 

 fittest." Natural selection is also known as Darwinism. 



379. By a similar process, the cultivator modifies his 

 plants. He chooses the variations which please him, and 

 from their offspring constantly selects for seed-bearing 

 those which he considers to be the best. In time he has a 

 new variety. Plant-breeding consists chiefly of two 

 things: producing a variation in the desired direction; 

 selecting, until the desired variety is secured. 



383. Variation. Big and little pigweeds of 

 the same kind. 



