56 A TEXT-BOOK OF BOTANY 
bark. In this way old inscriptions have often been un- 
covered. 
The well-known operation of grafteng depends upon 
the ability of plants to heal wounds. The plant upon 
F which the operation is 
performed is called the 
stock, and the twig graft- 
ed into it the scion. An 
ordinary method, called 
clejt-grafting, is to cut off 
the stem or a branch of 
thestock, split the stump, 
insert into the cleft the 
wedge-shaped end of the 
scion, and seal up the 
wound with wax or clay. 
The cambiums of the 
stock and the scion must 
be put into contact at 
some point; and hence it 
: is usual to insert a scion 
Fic 55.—Cleft-grafting showing scions in in each side of the cleft, 
-place (4) and the wound sealed with since the cambium of the 
clay or wax (B). : 
stock is comparatively 
near the surface (Fig. 55). The cambium of stock and 
scion unite, the wound heals, and the scion becomes as 
closely related to the activities of the stock plant as are 
the ordinary branches. The scions are usually cut in the 
fall, after the leaves have fallen, are kept through the winter 
in moist soil or sand, and the grafting is done in the spring. 
A number of important things are secured by grafting, but 
chief among them is the perpetuation of useful varieties 
with certainty and at a great saving of time. 
(2) ALonocotyledons.—In this great group of plants the 
vascular bundles of the stem are not arranged so as to form 
