Callusing and Repairing 97 
than large ones. The proper practice is, therefore, to prune 
in time, so as to avoid the cutting of large branches. 
Inprder tO SECUTE 2& pesseeisieis 
satisfactory proportion be- 
tween the amount of food 
material used in making 
callus, and the supply, it 
is best not to make too 
many large wounds at 
once, and, if possible, no 
wounds larger than four 
to six inches in diame- 
ter. Three medium-sized 
branches of from three to 
four inches in diameter 
may be safely removed in 
any one year, even from 
old trees, and the wounds 
will heal in from three Fic. 27- — An example of proper prun- 
ba eae years, while young ing, but with the wound left undressed. 
vigorous trees will elaborate enough food material to take 
care of a larger number. 
The wounds on young trees and in the younger portions 
of the trees heal more readily than those on old trees and 
; those near the base, removed 
from the food-elaborating foli- 
age. In very old trees which 
are underfed, the callusing pro- 
cess may go on with exceeding 
slowness or may even be entirely suppressed. Wounds on 
the lower side, shedding water more readily, are less 
dangerous than those on the upper side of limbs. 
In general, the fewer and the smaller in extent the wounds 
FIG; 28; —= Imported bill hook. 
