GRAFTING 139 with it the scion or graft. No attempts to- ward grafting plants on others which do not belong to the same natural order have been successful. Generally speaking, varieties suc- ceed best on varieties, species on species, or species and varieties on allied genera. All our cultivated fruits, for instance, are improved varieties of some original species. Out of thousands of varieties raised from the seeds of some previous excellent variety, it is not likely that any will be precisely like the immediate parent; some few may be equal or superior to it, but the great majority will be inferior. When a new and decidedly valuable variety occurs, it becomes a matter of importance to perpetuate it in as many individual plants as possible, and this, with trees, is usually done by grafting. The trifling effect that the stock has upon the scion enables the poorer varie- ties to be employed in furnishing the trunk and root to the smaller and younger scion. A piece of well ripened wood, in the form of a twig of the growth of the previous season hav- ing three or four buds upon it, is thus transferred to the poorer kind, and forms a living extrem- ity, which extends itself into branches and forms a new head or top. Fruit trees are grafted on plants of their own kind, called free stocks, or they are grafted upon a related variety or species to accomplish some particu- lar end. Certain stocks induce early fruiting and a dwarfed growth ; to dwarf the apple, it is grafted upon the paradise, a distinct varie- ty of apple ; the pear is dwarfed by grafting upon the quince. A species of cherry called the mahaleb (prunus mahalcb) is used for dwarf- ing the cherry, and the sloe and the beach plum for the plum. The peach upon its own roots does not grow well in stiff and cold soils, and for such situations it is worked upon a plum stock. The pear will grow when grafted upon the apple, but the union is short-lived ; it is also sometimes grafted upon the thorn and mountain ash, but such unions are a matter of fancy rather th an utility; nurserymen use only the stocks we have mentioned. The raising of stocks is an important part of the nurseryman's business ; though a tree may be grafted at almost any age, in nurseries where hundreds of thousands are worked every year the stocks used are as small as practicable. Free stocks for the apple and pear are raised from seeds, while the dwarfing paradise and quince stocks are grown from layers and cuttings. Most of the grafting in nurseries is done indoors in the winter. The stocks, which are a quarter of an inch or more in diameter, are taken up in the autumn and buried in an accessible place ; when worked, the root is shortened, the top cut off, and the scion inserted at the " collar," or where root and stem join. The grafted roots are set in boxes of sand and kept in a cellar until they can be planted in spring. The operation is performed with great rapidity, and several me- chanical appliances have been devised for facili- tating the work. Sometimes pieces of the root are used as stocks, but there has been much dis- cussion and great difference of opinion as to the value of the trees so produced. Stone fruits are more difficult to graft than the apple and pear, but if it- be done sufficiently early in spring the plum may be so treated very suc- cessfully ; the peach is rarely grafted at the north, but it succeeds at the south ; this fruit is usually propagated by that form of grafting called budding. Although fruit trees are graft- ed with scions of ripened wood, there are some trees which will only succeed when green wood is used for both scion and stock; this kind of grafting is called herbaceous. Many ever- greens can be grafted in the ordinary way, but the pines only succeed with herbaceous graft- ing, and the same may be said of some nut- bearing trees. Ornamental trees of various kinds are propagated by grafting, especially where it is desired to perpetuate some indivi- dual peculiarity, such as a pendent or weeping habit, or foliage of an unusual shape or color. Some weeping trees which are naturally low, as the weeping beech, ash, and poplar, form elegant specimens when grafted upon a stock 8 or 10 ft. high. Among ornamental trees and shrubs grafting is resorted to as the most rapid means of propagation: sometimes a variety cannot be multiplied readily from cut- tings, but can be grafted upon some related stock that will grow rapidly. The choicer species of clematis, now so much prized as ornamental climbers, take root with great difficulty, while some of the older kinds strike root freely; the florist grows these from cut- tings, and grafts the more difficult subjects upon their roots. The fine double camellias will not grow from cuttings, but are propaga- ted by grafting upon the single kinds which readily do so. Epiphyllums and other trail- ing cactuses make fine plants by grafting them upon a stout stem of cereus triangularis or one of the pereskias. Successful grafting of the apple upon the maple, the rose upon the black currant, and the like, is impossible, al- though instances of it are often narrated. The utility of the operation of grafting de- pends upon the fact that a bud is the repre- sentative of the tree from which it is taken; it has the possibility of unlimited development ; and as it will, if allowed to extend into a branch on the tree where it has formed, repeat all the characters of the tree, so when taken from the tree which produced it and planted as it were in the substance of another tree, it will develop a branch like the parent tree, and not like the stock with which it is united. Between the wood and bark of exogenous trees, inclu- ding all northern fruit trees, there is a layer in which the forces of vegetation are most active ; here the wood of the tree receives each year a layer of new wood, outside of the old, and the inner bark has deposited upon it a new layer upon the inside of that of previous years. This portion, which is neither perfect wood nor bark, but the place where both are
