43 
PLANT STRUCTURES. 
The proper erection of structures for the preservation or 
culture of plants is a matter of such importance, that it requires 
some consideration and explanation : many obvious blunders 
are frequently committed, and the most disastrous conse¬ 
quences occur through a want of knowledge of the right prin¬ 
ciples on which such structures should be erected, and this is 
a subject intimately affecting every one connected with horti¬ 
culture,—whatever the relation, the effect whether injurious or 
beneficial, according to the principle employed, soon evinces 
itself, and is observable from the common garden-frame to the 
most costly stove. 
Erections for the conservation of plants are of several grades, 
and vary, or should do so, in their appliances and means, ac¬ 
cording to the nature and character of the plants they are in¬ 
tended to protect, and these, in a general collection, being 
natives of widely distant countries of the most opposite geological 
characters, require also distinct methods of management, one 
point in which, of the first consequence, is their relative position 
to the sun’s rays. It is always necessary that we imitate, as 
closely as practicable, the natural position of plants in their 
artificial management, for the chances of success lessen as we 
depart from this rule, and, in a collection in no way uncommon, 
we may have plants from very many parallels ; some from situa¬ 
tions exposed to the immediate and direct influence of the sun, 
without any intervening shade to ward off or reduce its intensity; 
others, again, from the deepest recesses of woods or umbrageous 
thickets, the power of light varying, in each case, with the lati¬ 
tudinal line. How, then, can we reconcile to any correct prin¬ 
ciple the appearance of a range of plant houses constructed for 
various plants, all of which, as it too often occurs, are of the 
same size and the same inclination ? or how can we reasonably 
expect successful operations to be carried on under such cir¬ 
cumstances? Light, in passing through the glazed roof of a 
plant-house, becomes refracted and decomposed—that is, each 
ray is bent more or less, according to the angle presented by 
