ORIGIN OP VARIETIES. 151 



which have several ears on a stalk, we may thus make 

 very prolific varieties. 



483. In these and similar cases, the change or modifi 

 cation from the original to the new variety is not generally 

 sudden, and soon accomplished, but is most commonly 

 slow and gradual. Tl^e seed must be carefully selected 

 year after year, till the desired change is fixed and firmly 

 established. New and somewhat permanent varieties may 

 be thus obtained. 



484. But the case is different when we cultivate pota 

 toes and other tubers, since we do not usually plant the 

 seed in such cases, the tubers being only an enlargement 

 of the stem beneath the soil, and when plants grow from 

 their buds or eyes, as they do in the ordinary manner 

 of raising potatoes, the same variety is extended or 

 increased with no change of character. 



485. New and distinct varieties of the potato may be 

 produced to any extent by sowing the seeds of the plant. 

 Thus the chenango, the pinkeye, and other varieties, were 

 first obtained from seed taken from the ripe bolls of other 

 varieties. After a new variety has been once made in 

 that way, it may be continued and kept up by planting 

 the tubers in the usual way. 



486. If a vine is produced from a layer of another 

 vine, the new vine is only a portion of the old one, and 

 can never become a new and distinct variety ; and so in 

 budding or grafting, the new growth is only a portion of 

 the same old tree from which the scion was taken, and 

 has precisely the same character as the tree from which 

 the bud or graft came, except so far as it may have been 

 changed by the difference of soil or locality. But if tho 

 seeds of the apple or of the grape are sown, new varieties 

 are obtained at once. 



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