THE USE OF SHOOTS FOR PEOPAGATIEG 197 



masses of wood parenchyma in the place of the normal wood 

 cells. This parenchyma, however, is more delicate and sensitive 

 to external conditions, and in the case of stone-fraits liable to 

 cause the exudation of gum. Indeed, Duhamel has already 

 pointed out that branches of the almond upon which shoots 

 of the plum had been grafted were liable to gummosis at the 

 juncture of stock with scion. 



If pears are grafted on quince or apple on Paradise stock, the 

 death of even healthy shoots of the scion will take place if the 

 soil is at all dry or there is an insufficient supply of roots. 

 In one case it has been proved that the injury to the roots 

 caused by transplanting was sufficient to cause the death of the 

 graft. Grafts made at the same time on similar trees, which 

 were, however, not transplanted, turned out quite successful. 

 Peaches grafted upon plums do not form successful grafts. 

 The scion forms a reddish wood and soon dies off. 



It is, however, remarkable that pears and apples which result 

 in successful grafts with rather distant forms do not unite 

 well if the stock and scion are nearly related. Apples unite 

 very well with pears, and the apple scion bears fruit at a very 

 early stage, but it dies very soon. Pears grafted on apples 

 also yield fruit for a time, but the scion very often shows an 

 excessive formation of wood. (This depends, of course, largely 

 upon the tendencies of different varieties to form wood.) This 

 often results in knotty excrescences near the graft, in the 

 premature dropping of fruit, or the production of flowers 

 without fruits, and in a crippling or complete dying away of 

 the crown. 



Evergreen scions are quite able to unite with stocks which 

 lose their leaves annually. Slips of the Cherry-Laurel {Prunus 

 Laurocerasus) are said to unite with the stock of the Bird-Cherry 

 {Prunus Padus). Quercus Ilex has been successfully grafted on 

 Quercus sessiliflora, and Cedrus Lebani on Larix euro'pcea. We 

 have, however, no observations of the grafting of species which 

 lose their leaves on evergreen stock. 



Lastly, we must mention the fact that hybridisation has been 

 occasionally brought about by grafting. Many instances of graft 

 hybrids will be found in botanical literature, but many of the 

 instances are of doubtful authenticity. But the possibility of 



