THE GIRTH-INCREASE OF DECIDUOUS TREES. 39 
or thereby, stood upon it. But besides this, before the ground 
was handed over to the officials of the Garden, shelter belts of 
young trees were planted on the north, west, south, and part of 
the east sides. 
When it became desirable to thin the belts, the selected trees 
were removed to new sites, the formation of the main avenue at 
the foot of the bank on the south side of the house, and of groups 
of the different species, being chiefly kept in view. Re-arrange- 
ments necessitated a second transplantation in not a few 
instances, and the removal of several much older trees from the 
Botanic Garden to the Arboretum was also undertaken. 
The general method of transplantation followed has been to 
remove infant trees without any previous preparation, but with 
trees from about 6 or 8 to 18 or 20 inches in girth the outer 
roots were severed by cutting a circle in the ground round the 
tree, which was left standing for a year, or even for two years, 
to encourage the growth of new roots in the enclosed “ ball” of 
earth. When transplanted the twigs were slightly pruned. In 
the case of unusually large trees—from 3 to 4 feet or nearly 
5 feet in girth—the circular cut became a trench 4 feet deep. 
-Another practice seriously affecting the girth-increase, and 
introduced about the same time, was the pruning of trees into 
a conical sharp-pointed form to promote upward growth. 
As most of the trees selected by me for observation soon after 
the establishment of the Arboretum were in the shelter belts, it 
was unavoidable that many of them should be transplanted, an 
of those that remained some were prepared for removal, and 
others were closely pruned for upward growth; thus my 
records were dislocated, at a varying number of years after 
their commencement, from these three distinct causes. The 
period before interference lasted in nearly every case long enough 
to determine what may be called the natural annual rate of 
girth-increase, and, as in most cases eleven years have elapsed 
since interference, not only have the immediate effects on the 
rate been well established, but the rates for several years 
after recovery from ints operations have also been generally 
determined, 
