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mechanical part of this practice is detailed in Du- Hamel , Miller, and most gardening books. It is ofprimary importance that the liber, or young bark, ofthe bud, and that of the stock, should be accu-rately united by their edges. The air and wet mustof course be excluded.
It is requisite for the success of this operationthat the plants should be nearly akin. Thus theChionanthus virginica, Fringe-tree, succeeds wellon the Common Ash , Fraxinus excelsior , by whichmeans it is propagated in our gardens. Varietiesof the same species succeed best of all; but Applesand Pears , two different species of the same genus,may be grafted on one stock. The story of a BlackRose being produced by grafting a common rose, itis not worth inquiring which, on a black currantstock, is, as far as I can learn, without any foun-dation, and is indeed at the first sight absurd. Ihave known the experiment tried to no purpose.The rose vulgarly reported to be so produced ismerely a dark Double Velvet Rose, a variety ofRosa centifolia. Another report of the same kindhas been raised concerning the Maltese Oranges,whose red juice has been attributed to their being-budded on a Pomegranate stock, of which I have ne-ver been able to obtain the smallest confirmation.
Heat can scarcely be denominated a secretion,and yet is undoubtedly a production, of the vege-table as well as animal body, though in a much