368 PRINCIPLES OF BOTANY, ETC. 
deformed, and prolific flowers, therefore, are sterile, 
because the stamens and pistil suffer in them. . But 
some plants are sterile only as far as they do not 
produce blossoms. ‘The cause of this. may be cli- 
mate, too much sap, improper soils, and ill treatment: 
Plants, which are transplanted from a warmer cli- 
mate into a colder, bloom very rarely. An artificial 
degree of heat, like thétr natural, is therefore fre- 
quently tiied, but not always with good effect. And 
indeed those who are totally unacquainted with the 
natural history of such plants, will scarcely: ever 
Succeed in’ that'way. An instance will: prove this: 
We know that all plants from the ‘Cape of Good 
Hope require more warmth in winter than in‘sum- 
mer, and we shall, by attending to: this simple fact; 
certainly obtain blossoms from them. Fruit-trees, 
when they have too much sap, and their outer 
bark is too thick, have only a very thin vascular 
ring annually formed; the sap therefore must 
ascend towards the top arid the boughs, and fruit- 
trees of that kind grow often without ever having 
blossoms. Gardeners try to remedy this, by lopping 
some boughs, cutting off part of the root, and by 
removing the plant to a sterile soil; but they are; 
notwithstanding all these precautions, often. disap- 
pointed. It is a surer method to bleed or scarily, 
such trees, as it has been’called, or to scratch super- 
ficially, and in a winding direction, their stem. and 
principal branches. ‘The vascular rings are then at 
freedom to expand, and the tree will most probably 
bloom and bear fruits without delay, as the circu- 
jation of the sap does not now go on with equal ra- 
pidity 
