ON THE INFLUENCE OF CLIMATE ON PLANTS. 
181 
admitted. It is not uncommon for amateurs and even gardeners to ascribe such 
effects to the want of air, but it is sufficiently evident that solar light is 
the most essential agent in the production of strong and healthy shoots, and also 
of large and handsome flowers, and that where there is any deficiency in the 
supply of this element, there will be a corresponding defect in the health and 
beauty of both plants and flowers. As we intend furnishing our readers in an 
ensuing number with some remarks on the general treatment of this genus, we 
refrain from enlarging here, and proceed to ofl*er a few observations on the fifth 
and last division which we proposed to institute of what are generally designated 
" greenhouse plants." 
Under the head of Miscellaneous Greenhouse Plants, we intend classing the 
genera Acacia, Banksia, ProtcBa, Fuchsia, and in short, all those greenhouse plants 
which possess no affinity in character or habit to eitlier of the four divisions pre- 
viously considered. Most of the plants of this class thrive best in a house where 
an abundance of light is supplied, and may therefore without impropriety be con- 
gregated together in a distinct house, and kept as near as possible to the glass. 
We may here be permitted to explain what we intend when we recommend allow- 
ing any plants a great degree of solar light, and also to enumerate the means of 
effecting that object ; and first, we would recommend that the aspect of the house 
should be as nearly as possible facing the south, or between this point and south- 
west : secondly, that the materials of which the roof of that house is constructed 
should be of the slightest procurable description, consistent with strength, so as to 
offer as little obstruction as possible to the sun's rays; and where expense 
is not so much regarded, curvilinear roofs will be found far superior to those of 
the usual construction : thirdly, it is of great importance that the plants should 
receive the rays of light vertically, and not obliquely ; that is, that they should all 
be placed so as to receive the light from the roof, in preference to the sides or front 
of the house ; it may here also be observed, that the roof of the house should be 
so inclined according to the sun's average declination, that there be the least possi- 
ble refraction of light ; lastly, that the plants should stand at a sufficient distance 
from each other, to admit of the access of light on all sides, and also be so arranged 
according to their sizes, that the smaller plants shall not be shaded by the larger 
ones. With reference to this latter particular, however, where the plants are 
placed out in the bed or border of the greenhouse or conservatory, it should be 
borne in mind at the time of planting them, that there may be a great diversity of 
age in the plants, and thus those which are at that time the smallest may ultimately 
become the largest ; so that they should not be planted according to their actual 
height, but according to that which they may reasonably be expected to attain, 
otherwise it will be found that those of more rapid growth will eventually deprive 
the others of the beneficial influences of the sun, and thus materially injure them. 
To the propriety of separating a collection of greenhouse plants into these five 
divisions we are aware that some objections will be entertained, since there are 
