THE LADIES MAGAZINE OF GARDENING. 
309 
The degree of humidity which is thus maintained is not, however, 
suited to all plants. Those which partake largely of a cellular structure, 
and possess a succulent character, and especially those which have fleshy 
leaves, bear best the atmosphere generally existing in these cases ; whilst, 
on the contrary, its continued humidity is unfavourable, says Mr. Ward, 
to the development of the flowers of most exogenous plants, exfcept such 
as naturally grow in moist and shady situations. If, indeed, we call to 
mind the vast quantity of moisture which many plants naturally exhale 
in the free atmosphere, and the check which their vegetation receives if 
the atmosphere continue for some time both humid and still, we cannot 
wonder that to such plants the moist air of these cases should be unsuited, 
and that many of them, placed in such circumstances, should, as it is said, 
“ damp off.” But others of a different character, whether growing in the 
soil or suspended from the roof, find always sufficient moisture to support 
a healthy vegetation. Hence the supply of water given to the soil in the 
first instance, being secured from waste, is successively absorbed, exhaled, 
and condensed within the case itself, and made to sustain over and over 
again the vegetation of the same plants, without suffering either the 
soil or the atmosphere to become at any time too dry to carry on that 
process. 
6. Condition of plants , in regard to heat , in close cases , and in the free 
atmosphere.'-— The condition next to be noticed is that which relates to 
temperature. In the list of plants growing together in these cases, are 
some which are natives of the tropics, others which have been brought 
from high latitudes, and others the growth of our own temperate clime. 
Now the varying effects of climate are well known so far to modify the 
characters and habits of plants, as to bestow on each region its peculiar 
and appropriate vegetation. Even in the same latitudes, climate is so 
changed by elevation above the sea, as to blend the vegetation of the tro¬ 
pical with that of the arctic regions ; the same mountain which enjoys a 
tropical climate at its base being found clothed, at different elevations 
above the sea, with the vegetation of every other clime ; the plants finding, 
in the different altitudes at which they grow, a climate that compensates, 
more or less completely, for the difference of latitude. It is a great merit 
in the plan of Mr. Ward, that it breaks down in a great measure these 
distinctions of climate, and the peculiarities to which they give rise, and 
enables us not only to grow together in the same soil and climate plants 
which naturally inhabited countries the most distant from each other, and 
flourished only in the most opposite climes, but to pass them from one ex¬ 
treme of climate to another, through all the intermediate gradations, with 
very little trouble, and without exposing them to any great risk. Thus, 
VOL. i.-~- no. x. s s 
