OF PROPAGATION BY GRAFTING. 235 



in~ water, so as , to secure a supply of water to the 

 scion by the capillary attraction of such a bandage. 

 Ind^vl, the ordinary practice of surrounding the 

 scion -uid stock at the point of contact with a mass of 

 grafting clay is intended for the same purpose ; that 

 is to say, to prevent evaporation from the surface of 

 the scioa, and to afford a small supply of moisture ; 

 and henuw, among other things, the superiority of 

 clay over the plasters, mastics, and cements, occasion- 

 ally employed, %hich simply arrest perspiration, and 

 can never assist in communicating aqueous food to 

 the scion. 



Here also must be noticed certain practices, which 

 experience shows to be important, of which theory of- 

 fers no obvious explanation. Mr. Knight, for exam- 

 ple, asserts that cuttings taken from the trunks of 

 seedling old trees grow much more vigorously than 

 those taken from the extremities of bearing branches ; 

 and it is an undoubted fact that the Beech, and other 

 trees of a similar kind, cannot be grafted with any 

 success, unless the scions are made of two-years' -old 

 wood ; one-year-old wood generally fails. 



What is called herbaceous grafting, or Tschudy 

 grafting, depends so entirely upon the same princi- 

 ples as common grafting, that a separate notice of it 

 is hardly necessary. Nevertheless, as it is sometimes 

 very useful, a few words may be given to it. When 

 two vigorous branches cross each otber, and press 

 together, so as not to move, they will often form an 

 organic union ; if two apples press together, or if two 

 cucumbers are forced to grow side by side in a space 



