THE COTTAGE GARDENER AND COUNTRY GENTLEMAN, November 8, 1859. 
81 
some place where they can he looked at from time to 
time, to see that decay does not take place. Dry out¬ 
buildings, where they can be secured from frost, will do, 
and at suitable times during the winter let them be looked 
over, and any diseased ones removed ; but let the heap be 
at all times covered up from the light, otherwise they 
become green, and taste badly when cooked. Mangold 
Wurtzel and Swede Turnips may, after being taken up 
and divested of their top and tip end of root, be stored 
away in like manner in some outhouse, if there be such a 
building to spare ; if not, they may be arranged into a 
long ridge not more than five feet wide at the bottom, 
and piled up as high as they can be, and a slight covering 
of straw or litter laid on, and then a few inches of soil, 
taking care to leave, at places along the top of the ridge, 
a few tufts of rough rubbish like small, short faggots, or 
tufts of straw, sticking upwards a few inches above the 
soil. These are what the workmen call chimnies, and are 
to take off any steam or heat that may generate in the 
heap. Beat the earth firmly on the ridge, so that the rain 
will run off instead of sinking into it; and if very severe 
weather set in, it would be advisable to give the heap an 
additional coating of something or other to keep out the 
frost. If nothing else be handy, it is better to cover it 
with snow than leave the naked sides exposed to the long- 
continued frosts we sometimes have. An extraordinarily 
severe winter occurring now and then, and taking a cycle 
of years, it may be looked for as being likely to be one 
in ten. But I am not a sufficient weather prophet to 
determine when the severe one will be. J. Robson. 
(To be continued.) 
PRINCE OE WALES HYACINTH. 
The short article of Mr. Beaton’s, headed “ Mauve Colour 
Verbena,” p. 54, of your October 25th number, in which he says 
the most magnificent thing at our Show last spring was the 
Prince of Wales Hyacinth, the only true mauve colour, and 
which he has recommended all fashionable families to purchase, 
has brought us a profusion of orders for it, which we are re¬ 
luctantly obliged to decline, in consequence of there being but 
ONE blooming root in this country, and that we intend to keep 
on purpose to show it at our Exhibition, which will take place 
during the week commencing the 12th of March next, to as 
many young ladies as may honour us with a visit, not only to 
select the various shades of mauve in this Hyacinth for their 
dresses, &c.; but also, we hope, to select such colours in 
Hyacinths as would be best adapted to produce effect m their 
respective gardens.— Wi. Ctttbush & Son, Highgale Nurseries.. 
THE SCIENCE OF GARDENING. 
(Continued from page 41.) 
Plants and their leaves, if excluded from light, become of a 
white or pale yellow colour, in which state they are said to be 
blanched or etiolated. This, as already noticed, is occasioned by 
their being neither able to decompose the water they imbibe, nor 
to inhale carbonic acid. In the dark plants can only inhale 
oxygen, and thus, deprived of free hydrogen and carbon, on the 
due assimilation of which by the leaves all vegetable colours 
depend, and saturated with oxygen, they of necessity become 
white. An excess of oxygen has uniformly a tendency to whiten 
vegetable matters ; and, to impart that excess to them is the 
principle upon which all bleaching is conducted. An over-dose of 
oxygen causes in them a deficiency of alkaline, or an excess of 
acid matter, and light enables plants to decompose the acid 
matter, and to restore that predominancy of alkalinity on which 
their green colour depends. Sennebier and Davy found most 
carbonic acid in blanched leaves; and all green leaves contain 
more alkaline matter than the rest of the plant which bears them. 
Every cook knows that a little alkali, carbonate of soda, added to 
the water, improves the green hue of her boiled vegetables. That 
this is the cause of the phenomenon is testified by direct ex¬ 
periment. Blanched Celery and Endive, and the white inner 
leaves of the Cos Lettuce, contain about one-third more water 
than the same parts when green ; and if submitted to destructive 
distillation do not yield more than half so much carbon. Then, 
again, if a plant of Celery is made to vegetate in the dark, under 
a receiver containing atmospheric air, with the addition of not 
more than one-twenty-fifth part of its bulk of a mixture of car- 
buretted hydrogen, and hydrogen such as is afforded by the dis¬ 
tillation of coal, that plant, though it beoomes paler than when 
grown in the daylight, still retains a verdant colour. 
So effectual is the metamorphosis of plants effected by exclud¬ 
ing them from the light, that Professor Robinson brought up 
from a coal mine, near Glasgow, some whitish-looking plants of 
which no one could detect the name or character. After ex¬ 
posure to the light the white leaves decayed, and were succeeded 
by green ones, which speedily revealed that the plants were 
Tansy. They had found their way into the mine in some sods 
from a neighbouring garden; but though they had retained life 
in its dark galleries, they had entirely iost their natural colour, 
odour, and combustibility. This is only in accordance with the 
gardener’s yearly experience ; for his blanched Sea-kale, Endive, 
and Lettuce are totally dissimilar in flavour and appearance to 
the plant left in its natural state. 
Sir H. Davy excluded a Cos Lettuce from the light. In six 
days it was rendered very pale, and at the end of another week 
it was quite white : the growth of the plant was checked, and the 
analysis of its leaves showed that they contained more carbonic 
acid and water, but less hydrogen and residual carbon, than an 
equal weight of green leaves. 
A Potato has been observed to grow up in quest of light from 
the bottom of a well twelve feet deep—and in a dark cellar a 
shoot of twenty feet in length has been met with, the extremity 
of which had reached and rested at an open window. In the 
leaves of blanched vegetables peculiar chemical compounds are 
formed. Thus in the blanched shoot of the Potato a poisonous 
substance called solanin is produced, which disappears again 
when the shoot is exposed to the light and becomes green (Otto.) 
In Asparagus, in blanched Clover (Piria), and other plants 
grown in the dark, asparagin is formed, and no doubt other 
peculiar changes take place, wdiich are not yet understood.— 
(Johnston's Lectures on Agricultural Chemistrg.) 
It deserves notice, that it has been proved by the experiments 
of Dr. Hope and others, that light from artificial sources may be 
concentrated so as to enable plants to absorb oxygen and perfect 
those elaborations on which their green colour depends ; and the 
light of the moon has a similar influence. A similar concentrated 
light will make the Pimpernel, and other flowers which close 
until sunrise, open their petals and rouse from their rest; a fact 
which gives another reason why plants in rooms frequented at 
night become weak and exhausted sooner than those that remain, 
as Nature dictates, unexcited at night. 
The yellow, red, and light brown tints which render the foliage 
of our plants so beautiful in autumn arise from the absorption 
of an excess of oxygen gas. When the reduced tempei*ature of 
the season deprives a leaf of the power to elaborate the sap, and, 
indeed, stops the circulation to it of that fluid, the absorbent 
powers of the organ are reversed, and, instead of carbonic acid, it 
inhales oxygen. The effect is speedily perceptible. Gallic acid 
forms, and this, modified by the various saline constituents of 
different leaves, changes the hue of their green colouring matter, 
called chlorophyll or chromide, into various tints of yellow, red, 
and brown. This is the general effect of acids acting upon 
vegetable greens, and that it is the cause of the autumnal change 
of colour in leaves is proved by the fact, that if a green leaf be 
dipped into an acid it assumes the same hue; and if some red or 
yellow leaves be dipped into an alkaline solution they are rendered 
green—the alkali evidently neutralising the acid that had wrought 
the unnatural change of colour. 
Changes similar to those resulting from age may occur merely 
from accident, as from the puncture of insects, the growth of 
parasitic fungi, or the blighting influence of frost. First they 
change to yellow ; then they change to red. 
But some leaves present naturally a different colour on each 
surface. The upper surface of the leaf of the Cyclamen is green; 
the under surface is red; yet the red chromule, in this case, 
exhibits the same chemical properties as the chromule that has 
been changed to red as the result of age.— (Macaire.) 
The hints and warnings which these facts suggest to the mind 
of every reflecting practitioner are numerous. They explain and 
enforce the necessity of a regular, and by no means as to quantity, 
indiscriminate, supply of water to plants ; the importance of 
shading after their transplanting, yet the avoidanco of unneces- 
