INFLUENCE OF CLIMATE ON PLANTS. 
61 
become acquainted with the fact, that the native vegetation of those tracts is 
capable of supporting and resisting the extremest degree of heat or cold which 
there occurs. 
If the observer allow his inquiries to cease here, they will be found essentially 
defective when the theory which may have been founded upon them is reduced to 
practice. The state of their functions at the time when these changes take place, 
and the usual duration of the hot or cold season caused by such alterations, yield 
only in importance to the extreme degree of temperature. Thus, if a plant be 
removed from its native climate to one in which the extremes of temperature are 
nearly correspondent, but occur at different periods, it must by no means be sup- 
posed that it will accommodate itself to the latter, until, by a gradual and natural 
adaptation, assisted by artificial shelter at particular seasons, a total change in the 
era of its periodical functions is effected. Again, there are peculiar districts within 
the tropics, which, on account of their great elevation, are annually exposed to a 
considerable diminution of temperature ; but though, in some such cases, the ther- 
mometer ranges equally as low as in the winters of temperate climates, the cold 
season is by no means so protracted. In attempting, therefore, to acclimatize 
plants from the former regions in those last mentioned, some protection must be 
afforded them on the approach of winter ; otherwise, their shoots not having been 
allowed the natural period to mature themselves, will be liable to serious injury 
from early attacks of frost, even though they should be less severe than what they 
are accustomed (but prepared) to endure with impunity in their native climes. 
More fully to illustrate our meaning, we may instance those countries which 
lie antipodes to us, and whose summer season consequently occurs at or nearly the 
same time as our winter. It is obvious that plants obtained from such places will 
not at once conform to the inversed epochs of our climate ; and that the greatest 
attention is necessary to inure and accommodate them. Nor is the period at 
which they are removed from their native soil, and their management during the 
voyage, of trifling importance. Plants taken from such districts at the commence- 
ment of their winter would arrive in this country at the same rigorous period, and 
thus have to linger through that unfavourable season during their usual stages of 
growth and development, and immediately after being subjected to all the debili- 
tating circumstances of a sea voyage. This would certainly be prejudicial to 
them. The best time, therefore, for shipping them, would be the decline of their 
winter, when we should receive them towards the commencement of our spring. 
In introducing any kind of plant from the tracts above-mentioned, the advan- 
tage of importing seeds in preference to living specimens will be clearly evident 
from the preceding remarks. Seeds will not only endure greater extremes of tem- 
perature during the voyage without injury, but they require no attention, and 
may be germinated at any desirable period after their arrival. Hence, if received 
during the autumnal or winter months, they may be safely kept till the ensuing 
spring before excitation. 
