Plant Breeding. 261 



There are two possible ways of fixing a desirable varia- 

 tion: 



a By propagating the plant by division (345). This 

 enables us to maintain a given variation through many 

 generations with comparatively little deviation from the 

 form with which we started (341). Our varieties of 

 fruits, potatoes, geraniums and many flowering plants, 

 and of many of our finest ornamental trees and shrubs 

 are fixed in this manner. It is well known that varie- 

 ties propagated in this way rarely "come true" from 

 seed, i. e., their seed does not usually produce plants of 

 the same variety as the parent. But it is not practicable 

 to propagate all plants by division. 



With plants more conveniently propagated from seed, 

 as the cereals, Indian corn and most garden vegetables, 

 we may fix varieties to a certain extent, 



b By persistent selection toward an ideal type. For ex- 

 ample, if we discover a single pea plant in a row of peas 

 that produces earlier pods than any other plant, and we 

 desire to fix this variation, we would save all the peas 

 from this plant and sow them the next spring. Most of 

 the plants from this seed will probably be later than the 

 parent, but two or three of them may equal it in earli- 

 ness. We would save the seeds from the earliest plant 

 again, and continue this selection through several sea- 

 sons. It would be well to note the incidental characters 

 of the earliest plants, i. e., whether the pods are borne 

 singly or in pairs, if they are straight or crooked, and 

 whether the plants are tall or dwarf. Having decided 

 on the characters that seem to accompany the extreme 

 earliness, we should save seeds only from plants that 



