24 Production of New Varieties. 



ous intermixture are constantly occurring. The crosses thus pro- 

 duced are shown only by raising fruit from the seedlings. 



In the annexed figure of the pear-blossom (Fig. 15), the five central 

 organs, a, are the pistils; the upper extremity of each is the stigma. 

 The surrounding thread-like organs, #, are the stamens, surmounted 

 by the anthers. When the flowers open, the anthers burst, and 

 discharge the pollen on the stigma, which operates on the embryo 

 fruit at its base. 



Fig- is- 



Flower of the pear a, stigmas ', o, 

 anthers. 



Fig. 1 6. 



Flower of the pear, with the anthers 

 cut out. 



The production of new varieties is greatly facilitated by cross- 

 impregnation, or by fertilizing the pistil of one variety with the pol- 

 len of another. This was performed with great success by Knight. 

 Selecting two varieties, while yet early in flower, and before the 

 anthers had burst and discharged the pollen, he cut out with a fine 

 pair of scissors all the stamens, leaving the pistils untouched (Fig. 

 1 6). When the stigma became sufficiently mature, which was indi- 

 cated 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 the finger for applying the pollen. The fruit, thus 

 yielded, was unchanged ; but its seeds partook variously of the nature 

 of both parents, and the trees growing from them bore new and 

 intermediate varieties. 



For the success of such experiments, several precautions are 

 requisite. The flower must be deprived of its stamens before it has 

 fully expanded, or before the anthers have already burst and scat- 

 tered their dust ; the pollen must be procured from a bursting or 

 fully matured anther, when it will be dry and powdery ; the stigma 

 must be inoculated as soon as it becomes adhesive or glutinous, 

 otherwise it may be fertilized from another source, and then the 

 intended pollen cannot possibly take effecl:. For, a stigma once 

 inoculated, cannot be inoculated again. It is safest, where pradica- 



