DEFECTS OF SHAFTING AND BUDDING. 347 



of the two parts, I have given a sketch of woods of dif- 

 ferent patterns, to show the impossibility of their meeting 

 and carrying on the circulation, unless they agree in every 

 respect; and that each contains a pretty equal quantity of 

 sap. (See PL X, Fig. 2, 3, 4, 5.) Conceive each of these 

 circular apertures to be cylinders, and supposing a quantity 

 of similar vessels laid close to each other in rows, and that 

 for the use of some machine a double quantity of vessel* 

 was wanted, to make it double the height, to convey the 

 liquid on through this whole series ; would it not be most 

 apparent, that the vessels so applied for the continuation of 

 the pipes should be formed of the same size, and of the same 

 shape, as the first ? and that, if they were cither larger, 

 or smaller, the liquid would escape in pouring from one set 

 to the other ? Just so it is with the cylinders in the wood 

 vessels of the stock and scion : except that, having no 

 apertures from which the sap can escape, it bursts the under 

 vessels, that should contain it. 



The next, thing necessary is, that the time for the flowing And also the 

 of the sap should be nearly the same both in the stock and fl" 1 ^ ° f t ^ e e 

 scion ; for every tree has its own peculiar period for this 

 operalion, and the energy with which it acts at that time is 

 to be traced to the most distant leaf. The current is then 

 very great, and the effort it makes is infinitely superior to 

 its motion on any other occasion. If any obstruction has 

 taken place before in the inner part of the tree, either by 

 the introduction of a worm, or the piercing through of any 

 cryptogamia (no uncommon accident) this is the clearing 

 time ; as the tree has then strength enough to force away all 

 heterogeneous matter, that hurts or impedes its growth. If 

 therefore the scion should advance to this period before the 

 stock, it will want the sap to act with, an! be debilitated 

 and starved, till the time for the stock arrives, when it will 

 have lost its energy : and if (|he flow of tk& sap takes place 

 in the stock first, the vessels of the scion will not be ready 

 for its reception, and it will probably burst them. I have 

 often found it in this state. In the one case the scion 

 appears shrivelled in its upper leaves, in the other; it leaks 

 at the graft, and decays often by slow degrees. 



The 



