BUDDING AND GRAFTING. 333 



found to have reference to the emission of roots by buds. 

 One common practice is, to head down the branch that is 

 laid into the earth ;. this is to call into action the buds below 

 the incision, by stopping the general axis of development. 

 Another method is to tongue the layer, that is, to split the 

 stem just up to the origin of a bud ; a practice that has the 

 effect of enabling the roots to be emitted into the soil through 

 the wound more readily than if they had to pierce through 

 the bark ; the resistance offered to their passage through the 

 bark is in many cases so great as to compel them to con- 

 tinue to make wood rather than to appear in the form that is 

 necessary for the success of the cultivator. 



BUDDING AND GRAFTING. 



Budding and Grafting are operations that equally depend 

 for their success upon the property that buds possess of 

 shooting roots downwards and stems upwards ; but in these 

 practices the roots strike between the bark and wood of the 

 stock, instead of into the earth, and form new layers of wood 

 instead of subterranean fibres. The success of such prac- 

 tices, however, depends upon other causes than those which 

 influence the growth of cuttings. It is necessary that an 

 adhesion should take place'between the scion .and the stock, 

 so that when the descending fibres of the buds shall have 

 fixed themselves upon the wood of the stock, they may not 

 be liable to subsequent separation. No one can have stu- 

 died the economy of the vegetable kingdom without having 

 remarked that there is a strong tendency to cohesion in bo* 

 dies or parts that are placed in contact with each other. 



GRAFTING. 



Two stems are tied together for some purpose: when the 

 ligature is removed, they are found to have grown into one: 

 two Cucumbers accidentally placed side by side, or two Ap- 

 ples growing in contact with each other, form double Cu- 

 cumbers or double Apples ; and most of the normal modi- 

 fications, of the leaves, floral envelopes, or fertilizing organs, 

 are due to various degrees of cohesion in contiguous parts. 

 This cohesion will be always found to take place in the eel- 

 lural tissue only, and never in the vascular tissue. In the 

 stems of all such trees as are grafted by orchardists, the cel- 

 lular tissue is found alive only in the medullary rays and the 



