174 APPLICATION OF PRINCIPLES. 



to fertilise the stigma, and, of course, no seed is pro- 

 duced. Or the carpels themselves may be converted 

 into leaves, and have lost their seed-bearing property. 

 Double flowers in the latter case cannot possibly bear 

 seed ; but in the condition first mentioned they may, 

 and often do. To bring this about, the cultivator 

 plants in the vicinity of his sterile flowers others of 

 the same species, in which a part at least of the 

 stamens are perfect, and they furnish a sufliciency of 

 pollen for the impregnation of the other flowers in 

 which there are no stamens. 



In some cases, principally in those of Composite 

 flowers, the seed is formed and advanced towards 

 perfection, and then decays; this is owing to the 

 flower heads of such plants being composed, in a great 

 measure, of soft scales, absorbent and retentive of 

 moisture, to which, in their own country, they are 

 not exposed in the fruiting season, but by which they 

 are affected under the hands of the cultivator. When 

 the heads of such flowers are soaked with moisture, 

 which they cannot get rid of, the scales rot, and decay 

 spreads to all the other parts, and thus the production 

 of seed is prevented. The Chinese Chrysanthemum 

 is a familiar instance of this. Such plants seed rea- 

 dily if the flower heads are kept warm and dry ; and 

 it is thus that the sterile Chrysanthemum has been 

 made seedful; that is to say, by growing it in a 

 dry warm winter border, protected from showers by 

 a roof of glass, or by using some such means of guard- 

 ing it ; or by rearing it in a warm dry climate. 



When seeds are freely produced, it is not altoge- 



