152 TILLERS OF THE GROUND CHAP. 

 CHAPTER XIII 



EXPERIMENTS IN PLANT -BREEDING 



WE saw in the last chapter that cultivated plants 

 have been improved very greatly since agriculture 

 began, and that most of them now occur in a 

 great number of varieties. We saw also that in 

 the first place improvements were brought about 

 simply by picking out the best plants and sowing 

 their seeds separately. A good deal of improvement 

 was brought about in this way, but it is a slow 

 and somewhat uncertain method. 



We saw next that for the last hundred and 

 fifty years or so another method has been more 

 and more adopted. This consists in crossing 

 different kinds of the same or similar plants, 

 these different kinds being sometimes obtained 

 from countries widely separated from one another. 

 The first result of this crossing is often to produce 

 a number of different kinds of seedlings. The 

 next step is to pick out the suitable seedlings, 

 and, by care and cultivation, helped often by fresh 

 crossing, to produce entirely new plants. 



When making new varieties was merely a matter 

 of picking out good kinds which appeared by 



