A little known species of herbaceous-grafting is the joining of parts of fruits. It is easily performed upon all fleshy fruits like tomatoes, apples, squashes and cucumbers. When the fruit is half or more grown, one-half is cut away and a similar half from another fruit is applied. Better results follow if the severed side of the parent or stock fruit is hollowed out a little, so as to let the foreign piece set into the cavity. The edges of the epidermis of the stock are then tied up closely against the cion by means of bass or raffia. The two parts are securely tied together, but no wax is required. This operation succeeds best under glass, where conditions are uniform and winds do not blow the fruits about. Even leaves may be used as stocks or cions. Any such succulent and permanent leaves as those of the house-leeks, crassula, and the like may have young shoots worked upon them, and leaves which are used as cuttings can often be made to grow on other plants. Seed-grafting.--A novel kind of grafting has been described in France by Pieron, which consists in using a seed as a cion. This has been used upon the grape. A seed is dropped into a gimlet-hole made near the base of the vine while the sap is flowing in the spring. The seed germinates, and after a time the plantlet unites with the stock. [Illustration: Fig. 87. Cion for bark-grafting] Double-grafting.--Grafting upon a grafted tree is known as double-grafting or double-working. It is employed for the purpose of growing a variety upon an uncongenial root or of securing a straight and vigorous stock for a weak and poor grower. Some sorts of pears do not unite well with the quince, and if it is desired to secure dwarfs of these varieties, some variety which unites readily with the quince must first be put upon it. The Angouleme takes well to the quince, and upon Angouleme dwarfs the Seckel and some other varieties are often worked. The last cion is usually set after the first one has grown one season, although both may be set at the same time. Double-grafting for the purpose of securing a better growth is often practiced. The Canada Red apple, for instance, is such a poor grower that it is often stem-worked or top-worked upon the Northern Spy or some other strong stock. The Winter Nelis and the Josephine de Malines pears are often double-worked for the same reason.