Chap. IV.] MISCELLANEOUS. 133 
heads and eradicate them. The trunkless heads 
on the wall, full of growth, leaves, and fruit, 
would be curious and beautiful objects! and 
the absence of the roots below would be a great 
convenience to the gardener ! 
We, indeed, see daily, in plashing thorn 
hedges, how small a quantity of wood and bark 
is necessary to form the connecting link between 
the head and the root, and permanently to pre¬ 
serve vitality. But if Mr. Wallis’s facts are 
facts, we should see them every day ; we should 
see the stems and branches of trees and under¬ 
wood, when cut, continue to grow, and their 
roots die. But what we do see is the exact re¬ 
verse of this. 
Mr. Wallis alludes also to the fact, that trees 
when cut down will sometimes shoot out in the 
next summer. This has been always known, and 
always accounted for by the elder physiologists 
as the effect of, what they called, the concrete 
sap previously stored in the tree. But as trees 
separated from their roots are separated from 
the source of their sap, these shoots never live 
after the first summer. 
As the roots of trees grow in length through Best time for 
_ . , . „ . .... transplanting 
the earth they are in perfect contact with it, with the ban 
and as they increase each year in girthing this 
