Hybridizing.--We have already seen that pollen from one flower may be carried to another of the same species, thus producing seeds. If pollen from one plant be placed on the pistil of another of an _allied_ species or variety, fertilization _may_ take place and new plants be eventually produced from the seeds. This process is known as _hybridizing_, and the plants produced by this process known as _hybrids_. [Illustration: In hybridizing, all of the flower is removed at the line (_W_) except the pistil (_P_). Then pollen from another flower of a nearly related kind is placed on the pistil and the pollinated flower covered up with a paper bag. Can you explain why?] Hybrids are extremely variable, rarely breed from seeds, and often are apparently quite unlike either parent plant. They must be grown for several years, and all plants that do not resemble the desired variety must be killed off, if we expect to produce a hybrid that will breed more plants like itself. Luther Burbank, the great hybridizer of California, destroys tens of thousands of plants in order to get one or two with the characters which he wishes to preserve. Thus he is yearly adding to the wealth of this country by producing new plants or fruits of commercial value. A number of years ago he succeeded in growing a new variety of potato, which has already enriched the farmers of this country about $20,000,000. One of his varieties of black walnut trees, a very valuable hard wood, grows ten to twelve times as rapidly as ordinary black walnuts. With lumber yearly increasing in price, a quick growing tree becomes a very valuable commercial product. Among his famous hybrids are the plumcot, a cross between an apricot and a plum, his numerous varieties of berries and his splendid "Climax" plum, the result of a cross between a bitter Chinese plum and an edible Japanese plum. But none of Burbank's products grow from seeds; they are all produced _asexually_, from hybrids by some of the processes described in the next paragraph. The Department of Agriculture and its Methods.--The Department of Agriculture is also doing splendid work in producing new varieties of oranges and lemons, of grain and various garden vegetables. The greatest possibilities have been shown by department workers to be open to the farmer or fruit grower through hybridizing, and by budding, grafting, or slipping. [Illustration: Steps in budding. _a_, twig having suitable buds to use; _b_, method of cutting out bud; _c_, how the bark is cut; _d_, how the bark is opened; _e_, inserting the bud; _f_, the bud in place; _g_, the bud properly bound in place.]