Improvenieiits Made in Plants by Man 429 



perfectly known. The earliest cultivators made use of them, and 

 the most scientific of horticultural experts have no others to-day. 

 For convenience of study we may consider them as three in 

 number and distinct, though in fact they are interwoven inex- 

 tricably. They are, — Selection of Variations; Preservation of 

 Sports; Crossing and Hybridization. And perhaps the reader will 

 here add in his mind ''and also Cultivation;'^ but he would be 

 wrong. Although cultivation can produce better individuals, it 

 cannot produce of itself better races, for the two are not the same 

 thing at all. 



1. The Selection of Variations. — The reader will already have 

 noticed the very close connection which exists between Evolution, 

 considered in the preceding chapter, and the Improvement of 

 Plants by man, or Plant Breeding, our immediate subject, — a 

 connection which explains the juxtaposition of the two chapters, 

 and is not badly expressed by calling Plant Breeding artificial 

 evolution. Moreover, the two have precisely the same basis, — in 

 Variation, which we must now consider rather more fully than was 

 needful before. 



If all the plants of one kind, or species, were born exactly like 

 one another, as crystals are, then, so far as we can see, no im- 

 provement of plants by man would be possible. But plants of 

 the same species are not born alike any more than are people of 

 the same race or even the same blood. In a field of Corn, are all 

 the plants of one height, or have they the same number of grains 

 to the ear? Are the Elms in a meadow all cast in the same mold 

 of grace? Are the flowers of any one annual precisely alike in 

 their hue? There is an experiment which my students try every 

 year, with a result that is always surprising to them, and a satis- 

 faction to me. From a large lot of seeds of the same variety and 

 crop, they select a definite number of grains just as similar as 

 possible in size, form, weight, color and other features; these they 

 plant at exactly equal distances apart, at the same depths and in 

 the same positions, in a box of evenly-mixed earth, which is then 



