484 JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 
many visitors were simply enraptured with them, one lady vowing 
that she would pay my greenhouse a nocturnal visit with the 
object of abstracting some of the “beauties.” Seedlings may be 
bought cheaply in May and June and make a fine display, but 
of course cannot be depended upon for variety the same as the 
named kinds. Some of the scarlets and crimsons are certainly 
magnificent; and readers of the Journal will perhaps be amused 
to hear that, wishing to increase my stock of named varieties, I 
proceeded early in April to cut up the tubers as if they had been 
so many Potatoes. To my great delight my collection had sud¬ 
denly quadrupled. But great was my disappointment, some three 
weeks later, on inspecting the tubers, or rather the pieces, in the 
pots to which they had been transferred, to find that they were 
all decayed. This is a lesson not easily forgotten, and, malgre moi, 
I was forced to send to Messrs. John Laing & Co. for a fresh 
stock. I flower my Begonias in 32-sized pots, unless they are 
extra-large plants, in which case they receive another shift. They 
can be depended upon to bloom from August to the end of October 
without heat. Of course they would bloom early in the summer in a 
warm house. 
Chrysanthemums.—Small cuttings are inserted in large GO’s, 
three in each pot, as soon as the blooming season is over, the old 
plants being then thrown away. Early in May they are transferred 
separately into 32-size pots, and about the end of June receive 
their final shift into id’s, which size I find the most useful for 
the Chrysanthemum. 
All the above plants I have found to give the least trouble 
and the greatest satisfaction. My chief difficulty arises with the 
Calceolarias, as the leaves shrivel up without the least notice 
just as the plants are about to bloom, and there is no apparent 
reason for their dying in this way. I may add that if a few 
Camellias are desired they will make charming companions 
for the Primulas, whilst Azaleas will add to the fine colouring 
of the Cinerarias, and half a dozen selected Fuchsias may lend 
an additional charm to the house when the Pelargoniums are on 
the wane and the Balsams are not yet in full beauty.—P. C., 
Jersey. 
WHAT PLANTS USE. 
(.Continued from page 468.) 
Vines and all other plants use carbon dioxide. They do more 
—they use up heat and light. It is not very easy sometimes to 
get people to understand this ; at least we have as often been 
rewarded by a shaking of the head in a manner indicating unbelief 
when we have verbally tried to explain that they did so. We 
hope we shall have more success with our pen. This is not the 
place to enter into a philosophical explanation of what heat and 
light are, but the following may help those who have given the 
matter no thought to understand that plants use up light and 
heat. Burn a piece of wood : while burning, heat and light are 
given out. Is this heat and light a new production ? Many 
persons regard it as so, but it is not. Both were stored up by the 
leaves of the growing tree. While water and carbonic acid gas 
are being decomposed in daylight, as surely as these are manu¬ 
factured into new form and stored up, so surely are light and 
heat stored up ; and when by the process of combustion these 
forms are again resolved into water and carbon dioxide, again 
the light and heat, which were latent in the wood, assume their 
original form. More than that: according to the rapidity of the 
combustion so is the evolution of light and heat, and in propor¬ 
tion of the amount of light to the heat in our plant houses is the 
opposite operation—the composing of hydro-carbon performed. 
Without heat the process cannot go on ; without light the process 
cannot go on ; and without water and carbon the process cannot 
go on. All these must be present at once to secure the building-up 
of tissue. The attempt to secure it with any two only will not 
do. Heat and light together without air may forward plants 
towards the maturing of their wood, fruit, or foliage ; but new 
material cannot be formed under such conditions. Heat and air 
alone are not sufficient to do it in the absence of light; and light 
and air alone are not enough—heat must also be present, and only 
the last seems to be generally understood. 
Bearing these facts in mind, where is the economy of shutting 
up heat which can never be used 1 In daylight it is, in one 
sense, useless without the air ; during darkness it is useless with¬ 
out the light. It is only useful in producing precocity at the 
expense of the quantity and quality of the fruit, for it does tend 
to the weakening of the Vines. And instead of burning coal to 
keep up a hurtful heat during the hours of darkness, would it not 
be far better to maintain the heat during daylight with it, and 
then keep up the heat with ventilation to the same extent as is 
usually done without ? We think so, and we act so, and are satis¬ 
fied that we are right—right in the way we have read the lessons 
science has taught us, and right in our practice. 
But circumstances compel us to make compromises. With a 
bright February sun, a house full of tender foliage, and an out¬ 
side atmosphere a number of degrees below freezing point and in 
rapid motion, the opening of ventilators would speedily work 
ruin. We have sometimes, under these circumstances, aired an 
early house by ODening the door into the next compartment and 
ventilating it freely. Sometimes there is no adjoining vinery. 
In that case we have opened the front ventilators a little and 
tacked a strip of scrim over the opening ; the air passed slowly 
through this and escaped all over the roof through open laps. In 
the case of houses with puttied laps—a bad practice—we have 
opened the top ones a little and put scrim over them too. We 
have done this also in the case of Melon and Cucumber pits and 
have found the practice good. 
Ventilating, even in winter, might be a simpler and a safer 
operation were our hothouse builders better up to their business. 
Very few houses are so ventilated that the air is warmed before it 
can circulate among the plants with safety. No better plan has 
been invented than that by Mr. William Thomson, Tweed Vine¬ 
yards. “ It is termed the hot-air ventilator, and consists of a 
sheath of copper placed over or encasing a row of the front pipes. 
The diameter of the sheath is 1 inch more than the hot pipe it 
encloses, consequently there is an open space all round the pipe 
inside the sheath. This cavity is fed with fresh air from the 
exterior of the house by a pipe 5 inches in diameter, which springs 
from the lower surface of the sheath and passes through the front 
wall of the house to the external air. There is a valve in this 
feed pipe to modify the supply of fresh air at pleasure. In the 
upper surface of the sheath is a double row of holes, so that the 
moment the cold air comes into the chamber round the pipe and 
gets hot, expanded, and lighter, it makes its exit through these 
holes into the general atmosphere of the house.” We quote from 
“ Fruit Culture Under Glass,” by D. Thomson. Another efficient 
simple “hot-air ventilator,” which may be seen at Brentham 
Park, Stirling, consists of a cast-iron pipe full of holes laid under 
the hot-water pipes and communicating with the outer air through 
the ends of the house. This has also a valve to regulate the air. 
Ordinary ventilators are all right in summer time, but in winter 
some such ventilators as the above should be in use in every 
house where genial temperatures are kept up. Indeed they are 
the best even in summer, for by their use cold draughts may be 
avoided. 
We have spoken hitherto of the admission of air to vineries and 
such structures. The principles we have endeavoured to lay down 
apply in all cases. All plants, however, do not demand the 
quantities of carbon which stroDg-growing Vines do. The amount 
of carbon assimilated by a growing Orchid is trifling compara¬ 
tively speaking ; and if we take into consideration the amount of 
carbon dioxide that must be continually escaping from decaying 
sphagnum, &c., the little air that is necessary to keep the air sweet, 
that which is always entering when doors are opened and through 
the laps in the glass and otherwise, there can be no doubt that, 
generally speaking, such plants do not require a change of air to 
anything like the extent of plants which consume carbon rapidly. 
Even stoves require little air, in winter at least, for then the 
plants require little. In summer it is somewhat different, especi¬ 
ally when houses are crowded with quick-growing plants, and the 
roof is covered with Allamandas, Passifloras, &c. Greenhouses 
require to be ventilated whenever the sun is out to keep down 
the temperature all the year round, and in dull weather during 
winter to keep away damp, so that these are generally ventilated 
efficiently. It is where high temperatures are necessary and 
when houses are crowded with foliage, that most mistakes are 
made. 
We intended to say more on the use plants make of water in this 
paper, but it is already long enough, so we will leave that over for 
another issue of the Journal of Horticulture .— Single-handed. 
DOUBLE FLOWERS—BEDDING PELARGONIUMS. 
I have been rather amused at the attack made by “ Single- 
handed ” on double flowers, and thought someone would take 
up the cudgels, which I see “ Y. B. A. Z.” has done in the matter 
of Boses. I have a theory that single flowers bear doubling better 
than those that have trusses—for instance, double Pelargoniums 
are not so fine as single, nor would a flower like a Verbena or 
Phlox Brummondii, or any of the suffruticosa section, be improved 
by doubling, though this rule will have its exceptions, as with the 
double pink May, and it seems that the double flowers last longer 
than the single. 
Has that beautiful single Dahlia, the Dahlia imperialis, which 
