156 
ON THE INFLUENCE OF CLIMATE ON PLANTS. 
exist only when their particular habits are correctly known, and until this informa- 
tion is acquired, it is vain to think of growing them to perfection. The ill success 
which is so frequently experienced, is in a great measure attributable to the use of 
improper soil, to unskilful potting, and injudicious watering ; but we imagine that 
one ordinary and cogent cause is the want of due attention to the influence which 
solar light possesses or exercises upon them. Every person who cultivates a 
collection of heaths, or even only a few species of them, must have had the 
mortification of witnessing some of his plants wither and die during the summer 
season, notwithstanding he had administered water to them three or four times in 
the course of a day. It becomes then a question of great interest with the cul- 
tivator how this lamentable catastrophe may be averted ; and some may be ready 
to ask, will not placing the plants at a greater distance from the glass, and admit- 
ting a free circulation of air by ventilation, preserve them from this sudden 
destruction ? — to which we answer, that the former of these practices is manifestly 
injudicious, being productive of great injury to the plants in dull weather, by 
causing them to become drawn and weakly, and consequently rendering them still 
more tender and susceptible of injury from the sun's influences ; while the latter 
method has been proved to be wholly ineffectual, as we (and we doubt not many 
other cultivators) have lost specimens of our most beautiful species in a hot 
summer's day, although the house in which they were kept was ventilated in the 
most perfect manner possible. This is no doubt the effect of the vehemence of the 
sun's beams causing such rapid and excessive evaporation that the functions of the 
plant are deranged or impaired to such an extent as to be unable to maintain the 
vital principle. We are not prepared to define the connexion between solar light 
and heat, nor to distinguish the influence of the former from the latter upon plants : 
it must be apparent to our readers that heat is so intimately concurrent with the 
immediate light of the sun, that, for practical purposes, it is impossible to consider 
them apart. We shall be excused, therefore, if in this article on " light " we appear 
to confound it with " heat." Solar heat and light are such invariable concomitants, 
that the means employed to mitigate the one, will necessarily in some degree 
diminish the other; indeed, when treating of light, we may be understood to 
include its inseparable associate — solar heat. 
From the foregoing demonstration of the powerful and injurious influence which 
the sun's rays exert on the various species of Erica^ it is palpable that they should 
never be placed indiscriminately amongst other plants which require a great degree 
of solar light, but should always be cultivated in a house by themselves ; and we 
are sure that no individual will deny that they are eminently worthy of this 
distinction, as well as of every care and attention that can be bestowed upon them. 
We are aware that some of the best heath cultivators have already practised this 
system, but we are anxious to see it more extensively adopted ; and what we now 
wish especially to enforce, as one of the most important advantages that may be 
derived from such a system, and as the result of our present inquiry into this 
