THE GIRTH-INCREASE OF DECIDUOUS TREES. 59 
II.—-EFFECTS OF PRUNING. 
Nearly all the observations on the effects of pruning were 
made upon trees in the shelter borders of the Arboretum. As 
explained in the Introduction, these trees had been on my lists 
for some years before being pruned, so that their previous rate 
of increase had been ascertained. In the autumn of 1895 all 
the trees in these borders were pruned, root and branch, in 
preparation for transplantation ; but, as it happened, only a few of 
the twenty on my list were transplanted, and thus an opportunity 
was afforded of studying the results of pruning in a considerable 
number of trees not afterwards disturbed, as well as in a few 
complicated by transplantation. By some mistake two or three 
of the trees were much over-pruned,* so that the prospects of 
recovery under such circumstances could also be ascertained. 
ACER PSEUDOPLATANUS. No. 16. 
In the north border of the Arboretum from the beginning till 
now. In 1892 it girthed 114 inches, and in that and the two 
following years increased at the rate of 31 mil., but in 1895 the 
increase unaccountably fell to 115. The amounts fell still further, 
after pruning, to 3? and 1}, and the average for six years—1896~ 
1901—was only 3%; but in 1902 there was a revival to 164, and 
the rate from 1903 to 1906 was 22, which is low for a tree of its 
species and age. _ In appearance the tree was always healthy. 
ACER CAMPESTRE. No. 12, 
Also in the north border from the first. Its girth in 1892 was 
134 inches, and from 1892 to 1894 the average rate of increase was 
324 mil.; but in spring 1895 it was noticed that the top branches 
were dead, and the increase in that year fell to8}. After pruning 
next year the increase unexpectedly rose to 254, and the rate till 
*This over-pruning, which I regret to say affected more trees than the two 
or three mentioned by Dr. Christison, amounted in some s to mutilation 
unfortunate consequences to many of the trees with which he dealt at the 
outset of his operations and until the over-pruning was observed.—Is.B.B. 
