,8 PRODUCTION OF NEW VARIETIES. 



must always be impregnated with pollen from staminate sorts. 

 Thus the seed obtained from the berries of every pistillate 

 strawberry are crosses, and if planted will produce new van- 

 eties In fruit-trees, the stamens and pistils are in the same 

 flower, but these two sets of organs often mature at different 

 times. Crossing is mostly effected by insects, which, becom- 

 ing thickly dusted with powder from one flower, plunge into 

 the recesses of another, and effect a cross-pollination. Where 

 many varieties grow in one garden, in close proximity, cases 

 of promiscuous intermixture are constantly occurring. The 

 crosses thus produced are shown usually only by raising fruit 

 from the seedlings. 

 In the annexed figure of the pear-blossom (Fig. 16), the five 



FIG. 16. Flower of the Pear. FIG. ly.-The anthers cut out. This 



a, Stigma ; b, anthers. should be done in the bud. 



central organs a are the pistils ; the upper extremity of each is 

 the stigma. The surrounding thread-like organs, b, are the 

 stamens, surmounted by the anthers. When the flowers open, 

 the anthers burst, and discharge the pollen which may fall on 

 the stigmas or be carried to the stigmas of another flower. 



The production of new varieties is greatly facilitated by 

 cross-impregnation, or by fertilizing the pistil of one variety 

 with the pollen of another. This was performed with great 

 success by Knight. Selecting two varieties before the flowers 

 had opened, and before the anthers had burst and discharged 

 the pollen, he cut out with a fine pair of scissors all the sta- 

 mens, leaving the pistils untouched (Fig. 17). When the 

 stigma became sufficiently mature, which was indicated by its 

 glutinous surface, he transferred the pollen of the other sort 

 on the point of a camel's hair pencil. Some propagators pre- 

 fer the point of a knife for applying the pollen. The fruit, 

 thus yielded, was unchanged ; but its seeds partook variously 



