STRUCTURE OF THE STEM 75 
90. Grafting. — When the cambium layer of any vigor- 
ously growing stem is brought in contact with this layer 
in another stem of the same kind or 
a closely similar kind of plant, the two 
may grow together to form a single 
stem or branch. This process is called 
grafting, and is much resorted to in 
order to secure apples, pears, etc., 
of any desired kind (Fig. 46). A 
twig known as the scion from a tree 
of the chosen variety is grafted on to 
any kind of tree of the same species 
known as the stock, and the result- 
ing stems will bear the wished-for 
kind of fruit. Often one species is 
grafted on another, as the pear on the 
quince or the apple. Rarely trees dif- 
fering as much as the chestnut and the 
oak may be grafted together. Some- 
times erafting comes about naturally 
by the branches of a tree chafing *t {2° Fit scion and stock 
d 5 are shown ready to be 
against one another until the bark united; at the right they 
: . are joined and ready to 
is worn away and the cambium layer 0. cy with senators GH, 
of each is in contact with that of the 
other, or two separate trees may be joined by natural 
Fic. 46. Grafting 
erafting. 
