142 LETTERS ON TREES. 



ment), formed of very distinct fibres, which surrounded 

 the extremity of the stock to some distance, forming a 

 kind of sheath. It was quite easy to perceive that 

 fibres had proceeded from the base of the graft, and 

 had spread themselves over the stock.* 



10. Here the stock had died. There was no living 

 Cambium-layer to unite with the bud of the graft; 

 and as this bud lived and continued to grow, it had no 

 help, so to speak, but to push out and send down roots. 

 No doubt the instance given by Richard is altogether 

 a rare one. It is but very seldom that a graft will 

 under such circumstances hold. But it is not on that 

 account the less valuable in relation to my argument.f 



11. But what is a rare event with the bud of the 

 Exogen, and a singular phenomenon when it does occur, 

 is the rule and order in that of the Endogen. The 

 terminal bud of the Palm cut off the tree and planted 

 in the ground, sends out roots. The bud of the Palm 

 resting on the summit of the tree, fifty feet high, does 

 the same — sending down through the cellular tissue 



* Richard, EUmens de Botanique, 5ieme Ed. p. 105 ; Lindley's 

 Introduction to Botany, 4th Ed. vol. ii. p. 193. 



t In the matter of grafting, it is found to be almost invariably 

 requisite that the graft and the stock should be of the same natural 

 family. May not the reason be, that as the bud of the graft and 

 the Cambium-layer of the stock are to be joined together in the 

 closest relationship, a certain organic suitableness between them is 

 part of the ordering of Nature — a suitableness of the like kind and 

 involving the like principle with that which restricts the pairing of 

 animals within certain degrees of consanguinity ? 



