BETTER PLANTS AND ANIMALS 9 



and forty-seven species of cultivated plants known to civilized 

 man, of which forty-four species have been cultivated for more 

 than four thousand years. Among these ancient plants are 

 wheat, barley, millet, sorghum, rice, flax, hemp, cabbage, onions, 

 turnips, grapes, apricots, peaches, pears, quinces, apples, olives, 

 figs, dates, and bananas. 



9. How new varieties are produced. Nearly every plant 

 which has been long in cultivation is represented by many dis- 

 tinct varieties. Indeed, the number of existing varieties of a 

 cultivated plant is likely to be closely related to the length of 



FIG. 6. Kinds of corn 

 From left to right the kinds of corn are pod, flint, pop, sweet, and dent 



time it has been in cultivation. In most cases the varieties are 

 especially developed with respect to some one or more of 

 their parts; for example, we have the great roots of the sugar 

 beet, the large leaf heads of cabbage and lettuce, the flower 

 heads of cauliflower, and the flowers of the cultivated strains of 

 pansies. The way in which new varieties are produced may be 

 best learned by studying the history of a few cases. 



10. The Concord grape a chance seedling. In the year 1840 

 some boys of the village of Concord, Massachusetts, who had 

 been gathering wild grapes in the woods, on returning to 

 their homes, strewed the seeds of their spoil upon the land of 



