THE PRINCIPLES OP BOTANY. 
331 
Caiiadci possessed a colder winter than England^ but lie over¬ 
looked the uncertainty of our summer climate, the difference 
often experienced between night and day, and the fact that ** 
June is not uncommonly colder than May. The growth, 
then of maize is possible with us in sheltered situations, 
when these effects are reduced to a minimum, or, from the 
same causes, in rare and exceptional seasons; but this not 
because we have induced a hardened sort, but because the 
induced or natural climate were suitable. The summer cli¬ 
mate of North America being both hotter and more equable 
than our own ; but the falling of the night temperature, 
producing even frost, in England, in the middle of summer, 
interferes with fecundation by killing the ends of the long 
delicate tassels of the pistil-flowers, so that thorough fecun¬ 
dation is impossible, the result of which is, that instead of 
cobs of corn regularly impacted with perfect seeds, only a 
small per-centage of seeds become fecundated, and the pro¬ 
duce is thus rendered small and uncertain. 
Again, in cultivation, the good farmer will And it profitable 
towards the end of his lease to grow the more delicate sorts 
of grain, which would be impossible with his land out of 
order; the reason being, not that we can acclimatise the 
finer white wheats, for example, but that we can completely 
change the climate by drainage, by well working the land, 
and by judicious manuring. 
Thought and reflection, consequent upon extended obser¬ 
vation, will teach us that acclimatisation, as commonly un¬ 
derstood, is one of the vanities of our time. We know that 
societies have been established in different parts of the world, 
ostensibly to acclimatise animals and plants, but it is doubt¬ 
ful whether the real constitution of either plant or animal 
has, in any case, been altered ; for though it is quite true that 
sundry plants which have been first grown as greenhouse 
specimens have ultimately been found to succeed in the open 
air, yet in all such cases it may be concluded that it was be¬ 
fore capable of withstanding a wider range of temperature. 
The Aucuha japonica was with us at first grown in the hot¬ 
house; it is now a common shrubbery plant, but it was 
before capable of withstanding our British climate. Potatoes, 
Dahlias, and Pelargoniums, are common examples of exotics 
doing well in our summer temperature, would yet die if ex¬ 
posed all winter. These examples are, however, appealed to 
as evidences of acclimatisation; and arguments derived from 
them are employed to forward the views of theorists. The 
philosophical botanist or zoologist soon comprehends the true 
meaning of such pretensions. 
