JULY. 
141 
them, I have found by repeated experiments, especially in tropical houses, 
that a difference ranging from 5° to 10°, Fahrenheit’s scale, exists between 
the temperature of the air and that of the water. I can scarcely conceive 
anything more prejudicial in the whole routine of plant culture, having a 
tendency to chill and paralyse root-action, than frequent waterings at such a 
dissimilar temperature. It is bad enough under any circumstances, but 
when we come to practise upon valuable tropical Orchids, the injury becomes, 
after a time, irreparable. 
Why should this be so ? Is it owing to the conservative tendencies of 
an initiatory practice ? Numbers, certainly, do seem disinclined to move 
out of the groove into which they settled down in the early days of their 
practice, while others have been bold enough to strike out of the beaten 
course, and ofttimes, too, not without success. Curiously enough, it has long 
been a custom to furnish bottom heat for Pines, and even Melons and Cu¬ 
cumbers, arranging the beds in such a way as to be from 5° to 10° higher 
than that of the surface, and good results have invariably followed. Tepid 
water has always been in request by our foremost Pine-growers, and formed 
one of the recommendations in every calendar of operations. Indeed, were 
any one to question the merits of the system as a whole, a hundred voices at 
least would be lifted up against him. Innovations make slow progress; for 
it is only a modern practice looking into the geothermal state of Vine- 
borders, and furnishing either by chambers or aerated passages an auxiliary 
means of preserving and dispensing heat to the roots. No one, unless he be 
a bigot, will venture to challenge or gainsay the good to be derived by the 
adoption of such a system. Any little dispute that has arisen as to the effi¬ 
cacy of heated Vine-borders is traceable to individuals resident in localities 
V 
having subsoils such as sand or chalk, which have greater power of retain¬ 
ing heat and parting with superfluous moisture than other subsoils, and 
therefore have less need of artificial appliances. And how, I would ask, is 
it that the practice is not universally carried out ? why is it not followed to 
a legitimate issue ? If we have unmistakable proof of an improved cultiva¬ 
tion in every advance made in accordance with a system, we may be certain 
that it is an innovation of the right stamp, worthy of imitation and adoption. 
So far as the practical gardener is concerned, there are no plants under 
cultivation that merit a more undivided attention, whether we look to their 
variety, the geographical range over which they extend, or above and beyond 
all, their monetary value, than the Orchidacese. Every little scrap of infor¬ 
mation from reliable sources is gathered up and noted down with an avidity 
only known to Orchidophilists and Orchidculturists. The physiological 
structure of the plants is so peculiar, so different to that of every other form 
of vegetation, as to render them pointedly interesting to every naturalist. 
That they are capable of resisting far more fatigue than any other plants is 
well known, and yet it requires the highest degree of cultural skill to main¬ 
tain a collection generally in a healthy state. They are also liable to diseases 
quite foreign to other plants, and, in this respect, approach a step closer to 
the animal kingdom. 
In the course of experience and experiment over a large and varied col¬ 
lection, I have found tangible benefits to accrue from studying the thermal 
condition of the compost in which the plants grow. 
I may state that it is no haphazard conjecture that I am about to pro¬ 
pound, but a simple statement of facts evolved during a ten-years practice 
upon an Orchidaceous collection. In the former period, although I managed 
to grow the temperate species quite satisfactorily enough, I could not 
manage the great subdivision of Yandese at all well. I found, especially in 
