PROPAGATION. 211 



acting- as a cement, not certainly by interj unction of 

 the ligneous fibres. 



A very interesting- problem on vegetable physio- 

 logy is, whether the stock is affected by the graft, or 

 the graft by the stock. In most cases, we observe 

 no change whatever, any more than if the grafted tree 

 had been raised from a cutting or a layer. No change 

 takes place in its habit, nor in the form of its leaves, 

 flower, or fruit. It receives from the stock appa- 

 rently the same nutriment it would have received 

 from its parent branch, supposing it to have been 

 selected and left to form a principal head thereon. 

 This is invariably the result of a union of congenial 

 stocks and scions. But when this last-mentioned 

 particular is not attended to, very different effects are 

 observable. Some of these have been mentioned 

 before, and which convincingly show, that the graft 

 may be either invigorated or dwarfed by stocks un- 

 congenial in habit with itself. The operation alone 

 induces moderate growth ; because in choosing scions 

 we take, or should take, them from the mature and 

 most fruitful parts of the tree we wish to propagate, 

 and not from the rank growing shoots of the stem, 

 or from the centre of the head. Plants have all 

 natural habits ; and some of them, fruit-trees among 

 the rest, have what may be called incidental habits. 

 The pendent position of the weeping ash, as before 

 observed, is incidental. This deformity can be trans- 

 ferred by grafts ; so any peculiar habit in the growth 

 of fruit-trees may be transferred in the same w r ay. 

 p 2 



