324 DIFFERENT MODES OF GRAFTING. 



which could not be procured from seed, and the hastening of the period 

 of fruit-bearing. Grafting a young twig on an older stock has the 

 effect of making it flower earlier than it would otherwise do. The 

 accumulation of sap in the old stock is made beneficial to the twig, 

 and a check is given at the same time to its tendency to produce leaves. 

 Although the general law is, that grafting can only take place between 

 plants, especially trees, of the same family, there are certain exceptions. 

 Loranthaceous parasites can form a union with genera in different orders. 



Mr. Knight did much to improve fruits by grafting. He believed, 

 however, that a graft would not live longer than the natural limit of 

 life allowed to the tree from which it had been taken. In this way he 

 endeavoured to account for the supposed extinction of some valuable 

 varieties of fruit, such as the Golden pippin, and many cider apples of 

 the seventeenth century. He conceived that the only natural method 

 of propagating plants was by seed. His views have not been confirmed 

 by physiologists. Many plants are undoubtedly propagated naturally 

 by shoots, buds, and tubers, as well as by seed ; and it is certain that 

 the life of slips may be prolonged by various means, much beyond the 

 usual limit of the life of the parent stock. The Sugar-cane is propa- 

 gated naturally by the stem, the Strawberry by runners, the Couch-grass 

 by creeping stems. Potatoes and Jerusalem Artichokes by tubers, 

 the Tiger lily by bulblets, and Achimenes by scaly bodies like tubers. 

 The fruits, moreover, which Mr. Knight thought had disappeared, 

 such as Eed streak. Golden pippin, and Golden Harvey, still exist, and 

 any feebleness exhibited by them does not appear to proceed from old 

 age, but seems to be owing to other causes, such as the nature of the 

 soil, cold, violence, and mutilation. Vines have been transmitted by 

 perpetual division from the time of the Eomans. A slip taken from a 

 Willow in Mr. Knight's garden, pronounced by him as dying from old 

 age, was planted in the Edinburgh Botanic Garden many years ago, 

 and is now a vigorous tree, although the original stock has long since 

 undergone decay. It is true, however, that a cutting taken from a 

 specimen already exhausted by excessive development of its parts will 

 partake of the impaired vigour of its parent, and will possess less con- 

 stitutional energy than that taken from a vigorous stock. 



In grafting, various methods have been adopted. One of these is 

 grafting by approach, or inarching, when two growing plants are united 

 together, and after adhesion one is severed from its own stock, and 

 left to grow on the other. This kind of adhesion sometimes takes place 

 naturally in trees growing close together. The branch of the same tree 

 may also be bent, so as to become united to the stem at two points. 

 This is often seen in the Ivy. The roots of contiguous trees occasion- 

 ally unite by a process of grafting, and to this is attributed the con- 

 tinued vigour of the stump of Spruce-trees cut down on the Swiss 

 mountains. This natural grafting of roots has been observed in the 



