SELECTION EVOLUTION 



231 





f 



of characteristics from parenl to offspring is heredity. 

 P>.\ "selecting the besl " for seed the farmer maintains and 

 improves his crops. 

 It is said thai "like 

 produces like." This 

 is true of the general 

 or average features, 

 but we have seen that 

 the reproductioD is 

 not exact . It is truer 

 to say that similar 

 p rod ii c e s similar. 

 Pig. 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 ou tin- left grew from one 12 in. high 

 and !.' in. broad. (For a historj of these parents Bee 

 " Survival <>f t he I Inlike," p. 261 . ) 



378. SELECTION. There is intense Btruggle 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 

 leasl adapted is the process designated bj Darwin's phrase 

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

 fittest." Natural selection is also known as Darwinism. 



379. 1 1 j o similar process, the cultivator modifies his 

 plants. Ik- chooses the variations whieh please him, and 

 from their offspring constantly selects for Beed bearing 

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

 new variety. Plant-breeding consists chiefly of two 

 things: producing a variation in the desired direction; 

 selecting, until the desired variety is secured. 



Variation Big and little pigweedi "i 

 the same kind. 



