262 Principles of Plant Culture. 



show all these characters. After following this kind of 

 selection eight or ten years, we may be able to introduce 

 a new variety of pea. 



It is impossible to so fix variations in plants grown from 

 seed that they will continue to come true without a cer- 

 tain amount of selection, hence varieties propagated by 

 seed continually tend to "run out," i. e., to lose their 

 distinctive characters. Seed growers find it necessary 

 to use the utmost care in maintaining their varieties, and 

 the more distinct a variety propagated by seed, the more 

 difficult it is to maintain. 



437. Seed Selection is of Great Importance. From 

 what has been said, it is clear that the cultivator cannot 

 afford to be indifferent as to the quality of the seed he 

 sows. It is not enough that the seed is fresh and plump 5 

 it should be of carefully-bred varieties. In the cabbage 

 and cauliflower, success or failure in the crop will depend 

 largely upon the quality of seed sown, and the same is 

 more or less true in all crops grown from seed. 



438. We Can Induce Variation, in some cases, by special 

 treatment of the parent plants, or by the use of a par- 

 ticular selection of seed. 



a By culture. It is generally conceded that culture 

 tends to promote variations that would not have appeared 

 in the wild state, in consequence of the changed growth 

 conditions. In improving wild plants, therefore, we 

 probably have a better chance of securing variation by 

 gathering seeds from such wild plants that have been 

 placed under high cultivation than from those that have 

 not been submitted to culture. 



b By growing seedlings. In plants habitually propa- 

 gated by division (345), as the apple, potato, dahlia etc., 



