104 
EFFECTS OF FROST AND SUN’S RAYS 
with the same view. But by far the best screens for the security of 
wall-trees, are made of ships’ old colours, or curtains made of the same 
kind of stuff (bunting). These, hung on hooks or staples at the top of 
the wall, and so contrived as to be let down or drawn up by brails * at 
pleasure, are perfectly safe, and easily managed as well against frost 
as for another purpose, to be alluded to presently. 
It is quite unnecessary to notice the other and more expensive 
expedients had recourse to for the protection of the flowers and 
earlier maturation of the fruit of those foreign trees in this country, 
as hot walls, paper-covered, and glazed frames, so well known to every 
gardener; but we may revert to that state of the air so injurious to 
those early flowering trees experienced in this country, and to which 
they are not subject in their own. The action of frost on these attenuated 
and delicate members of a flower, and which, in fact, destroys them, is 
commonly supposed to arise from the expansive force of the congealed 
fluids bursting the cells and vessels containing them, and so destroying 
the organisation. The two most essential parts of a flower are the 
stamens and stigma, both of which are composed of purely cellular 
membrane, and the latter, wholly divested of cuticle, and when perfect 
always moist, must necessarily be quickly frozen ; and, moreover, as 
the style is simple and filiform, this (even if the stigma, from the viscid 
consistence of its moisture, should escape,) must very soon also be 
injured. These parts of the flower then being ruptured, are useless, 
and no perfect fruit can possibly be produced. 
This being the usual consequence of frost on the flowers of plants, 
renders necessary the precautions for their defence above adverted to. 
The necessity of giving support and shelter by placing the trees against 
walls, also operates injuriously by inciting the trees into action sooner 
in the spring than is wished ; and therefore whatever retards the 
flowering is of service, by lessening the risk of the bloom being hurt 
by late frosts. The best practice, as regards this point, is to unnail 
all the flower-bearing shoots from the wall early in November, allow¬ 
ing them to jut loosely from it all winter, and until pruning time, 
which need not be performed till the flowers are just ready to 
expand. This removal gets the shoots out of the strongest heat 
reflected from the wall, and consequently delays their flowering. 
There is one thing, however, which should regulate the time when 
peach, nectarine, and apricot trees should be unnailed: if the young 
bearing wood be well ripened, the sooner the unnailing is performed the 
* Lines having one end fixed at the top, and passing down behind, and under the lower 
edge of the curtain, and carried up on the outside and passed through an eye-bolt or staple 
at the top, and again brought down to the hand. This pulled, draws the curtain to the top. 
