INFLUENCE OF CLIMATE ON PLANTS. 
157 
roots of those which are in the open ground. In both cases, the amount of moisture 
received is lessened, and a lower degree of heat is competent to perform nearly the 
same service as an adequate temperature would under ordinary* circumstances ; 
saving, of course, that the accretions are circumscribed in extent, which is of no 
real importance. 
Orchidaceous plants are universally presumed to derive advantage from a few 
months' repose from active growth ; but it may be safely affirmed that it is not 
rest itself which elicits their dormant disposition to flower, this latter function 
being made palpable solely by the desiccating influence of heat. The proper 
nature of this repose is, therefore, evidently a degree of aridity proportionate to 
the rate of temperature. Where no artificial heat is employed, water may be 
entirely suspended ; and never should there be more applied than will suffice to 
preserve life. Assuming this opinion to be correct, the natural inference is, that 
what is called a season of rest should be termed a period of drought or maturation. 
It seems ridiculous to suppose that actual dormancy can be in any way useful ; 
for this condition can only be beneficial, when so modified that heat may predo- 
minate over moisture. And if these two agents were adapted to each other 
throughout the growing season, maturation would be completed ere the commence- 
ment of cold weather, and the plants might then remain in a cool, dry house, and 
perfectly torpid, during the winter. 
With respect to very young exotic plants, of all kinds, it is plain that their 
treatment should be essentially different from that pursued towards plants which 
are wished to flower profusely. So far from endeavouring to restrain their 
growth, every means, consistent with health, should be resorted to, which can in 
any way facilitate it. Precocious developments are, however, greatly to be 
deprecated ; and (orchidaceous plants excepted) stimulation must not be extended 
beyond the natural period. By potting them frequently into larger pots, liberally 
bestowing water, and judiciously increasing the natural heat in summer by 
artificial aids, they may be much more rapidly prepared for a state of vigorous 
production and beautiful display than is ordinarily the case. After the attainment 
of this epoch, the policy we have before recommended may be commenced and 
followed. 
When plants have flowered very abundantly, and there is any probability of 
their relapsing into a state of sterility in the following year, this consequence may 
be partly averted by the administration of a large portion of nutrimental liquid 
food, accompanied by a greater ratio of heat, immediately upon the fading of the 
flowers. Tropical, or other very tender species, that are not disposed to flower 
freely, should never be allowed to bear seed, unless they grow too luxuriantly, or 
this is indispensable for their propagation ; as such a process has a most debilitating 
effect, and one which sickly plants of this kind are unable to endure without injury, 
on account of their being so unnaturally circumstanced. 
The results of many experiments, casually obtained, render it, in our opinion, 
