GRAFTAGE. 65 



other conditions. The one essential point is to make sure that 

 the cambium layers, lying between the bark and wood, meet as 

 nearly as possible in the cion and stock. This cambium is al- 

 ways present in live parts, forming woody substance from its 

 inner surface and bark from its outer surface. During the 

 season of greatest growth it usually occurs as a soft, mucilagin- 

 ous and more or less unorganized substance, and in this stage it 

 most readily repairs and unites wounded surfaces. And for this 

 reason the grafting and budding of old trees are usually per- 

 formed in the spring. Later in the season, the cambium be- 

 comes firmer and more differentiated, and union of woody parts 

 is more uncertain. It is also necessary to cover the wounds in 

 order to check evaporation from the tissues. In out-door work 

 wax is commonly used for all species of graftage which wound 

 the wood itself, but in budding, the loosened bark, bound down 

 securely by a bandage, affords sufficient protection. It is com- 

 monly supposed that an ordinary cleft graft cannot live if the 

 bark of the stock immediately adjoining it is seriously wounded, 

 but the bark really serves little purpose beyond protection of 

 the tissues beneath. A cion will grow when the bark is entirely 

 removed from the stub if some adequate protection can be given 

 which will not interfere with the formation of new bark. The 

 cion must always possess at least one good bud. In most cases, 

 only buds which are mature or nearly so are used, but in the 

 grafting of herbs very young buds may be employed. These 

 simple requirements can be satisfied in an almost innumerable 

 variety of ways. The cion or bud may be inserted in the root, 

 crown, trunk or any of the branches ; it may be set under the 

 bark simply or inserted into the wood itself in almost any fash- 

 ion ; and the operation may be performed either upon growing 

 or dormant plants at any season. But in practice there are 

 comparatively few methods which are sufficiently simple and 

 expeditious to admit of generaLuse. 



Graftage may be divided into three general divisions, between 

 which, however, there are no decisive lines of separation : r. 

 Bud-grafting or budding, in which a single bud is inserted upon 

 the surface of the wood of the stock. 2. Cion-grafting or graft- 



