252 



BOTANY 



In spite of the physiological union between the old stock and the newly 

 formed growth, from a morphological standpoint they lead an altogether separate 

 and distinct existence. They may, however, exert an influence on each other ; 

 thus annual plants grafted on biennial or perennial stocks attain an extended 

 period of existence. In its structural character, forms of tissues, mode of second- 

 ary growth, formation of bark, etc., each maintains its own individuality. In 

 special cases it has been affirmed that they do mutually exert, morphologically, 

 a modifying effect upon each other (graft-hybrids). This could only result from 

 fusion of the protoplasts of stock and graft in the callus (Fig. 247). 



In practice several different methods of inserting grafts are in use, but only 



Fie. 215. 



-Different modes of grafting ; /, Crown grafting ; //, splice grafting ; ///, Imrt grafting ; 

 IT, stock : K, scion. 



the more important can be mentioned here. GRAFTING is the union of a shoot 

 with a young and approximately equally-developed wild stock. Both are cut 

 obliquely with a clean surface, placed together, and the junction protected from 

 the entrance of water and fungi by means of grafting wax (Fig. 215, II. ). 

 Cleft or tongue grafting is the insertion of weaker shoots in a stronger stock. 

 Several shoots are usually placed in the cut stem of the stock, care being taken 

 that the cambial region of the different portions are in contact, that the cortex of 

 the shoots is in contact with that of the stock. In other methods of grafting the 

 cut end of the shoot is split longitudinally and the cut shoot inserted in the 

 periphery, or a graft may be inserted in the cortex or in the side of the stock. In 

 grafting in the cortex the flatly-cut shoot is inserted in the space cut between the 

 bark and the splint wood (Fig. 215, /.). In lateral grafting, the shoot, after being 

 cut down, is wedged into a lateral incision in the stock. 



A special kind of grafting is known as BUDDING (Fig. 215, ///.). In this process 



