PLANT-BREEDING 269 



ation by gathering seeds from such wild plants that 

 have been placed under high cultivation than from those 

 that have not been submitted to culture. 



By growing seedlings. In plants habitually prop- 

 agated by division (345), such as the apple, potato, dahlia 

 and the like, we secure variation by growing plants from 

 seed. The parent plant, not having been fixed by long 

 selection, as is the case with varieties grown from seed, is 

 in a state of variation, and hence its progeny usually 

 vary widely. From these variable seedlings, desirable 

 individuals may be selected for fixing. Since most of 

 our varieties that are propagated by division are highly 

 developed, their seedlings are usually, though not neces- 

 sarily, inferior to the parents. 



By crossing varieties or species. This is the most 

 important method of plant improvement. By procur- 

 ing fecundation of the germ cell of a plant of one vari- 

 ety with pollen from a plant of a different variety or 

 species (149) through cross-pollination (151), we ob- 

 tain a variable progeny of which the individual plants 

 may be expected to resemble both parents in different 

 degrees. For example, if we secure fecundation of a 

 number of ovules of the Worden grape with pollen from 

 the Delaware grape, and plant the seeds from the fruits 

 thus secured, we may expect that some of the seedlings 

 will resemble both parents about equally, that others 

 will chiefly resemble the Worden, but will show a few 

 characteristics of the Delaware, while others again will 

 chiefly resemble the Delaware, but will possess a few 

 characteristics of the Worden. It would not be surpris- 

 ing if we secure a vine having the vigor, productiveness 

 and large fruit of the Worden, with the color and delicious 

 flavor of the Delaware. This we may almost certainly 



