254 



BOTANY 



PART I 



become united with it, if they are so placed that the side originally- 

 outermost occuj^ies the same relative position in the new organ, but 

 if this position is altered no such union takes place. Such grafting 

 experiments are of interest from another point of view. When the 

 two portions unite and fuse no regeneration takes place. One adopts 

 the root system of the other and conversely is ado^Dted by this. This 

 leads us to consider the mutual relations of parts of the plant or what 

 is known as correlation of growth {^'^). This plays an important 

 part in the normal ontogeny and leads, not only to the suppression of 



Fig. 208. — Different modes of araftina 



; /, Crown grafting ; II, splice grafting ; III, bud grafting 

 IV, stock ; E, scion. 



an organ that might develop, but also to the origin under certain con- 

 ditions of new organs. Its influence will be frequently alluded to. 



Artificial grafting, like artificial propagation, plays an important part in 

 horticulture. A cut off portion of a plant bearing buds, tlie scion, is induced to 

 unite with another rooted plant which is called the stock. 



In ])ractice several different methods of inserting grafts ar(^ in use, but only 

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

 witli 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. 208 //). 

 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 canibial region of the different portions are in contact, and that the cortex of 



