THE COTTAGE GARDENER AND COUNTRY GENTLEMAN, July 10, 1860. 
230 
Their organisation closely resembles that of the branch by 
which they are borne, and they are only its parts taking other 
forms. “Tracing,” says the late Mr. Knight, “the progress of 
the organisation in the full grown fruits of the Apple and Pear, I 
found, as Linnaeus has described, that the medulla, or pith, 
appeared to end in the pistils. The central vessels diverged 
round the core, and approaching each other again in the eye of 
the fruit, seemed to end in ten points at the base of the stamens, 
to which, I believe, they give existence. The spiral tubes, which 
are, in all other parts, appendages to these vessels, I could not 
trace beyond the commencement of the core ; but as the vessels 
themselves extend through the whole fruit, it is probable that 
the spiral tubes may have escaped my observation.” 
Although the medulla is traced to the base of the pistils, the 
central vessels to the part enveloping the seed, and to the 
stamens, and the spiral vessels throughout the fruit, yet over 
every part is extended the parenchyma and epidermis, and the 
sap circulates through the entire of the flower and fruit,—ascend¬ 
ing, being elaborated, and descending,—as regularly as through 
other parts of the plant. Coloured infusions may be traced 
through the vessels in the stem to the fruit, and if a ligature be 
passed round a Peach or an Apple, the enlargement is greatest 
above—that is, between the ligature and the footstalk ; and Mr. 
Knight succeeded, by intergrafting, in proving that the-leafstalk, 
the tendril of the Vine, the fruitstalk, and the succulent point 
of the annual shoot, may be substituted for each other,—a 
bunch of Grapes grew and ripened when grafted upon the leaf¬ 
stalk ; and a succulent young shoot of the Vine, under the 
same circumstances, acquired a growth of many feet. 
The stamens can be removed without preventing the formation 
of fertile seed; but their loss must bo supplied by tlio intro¬ 
duction to the pistils of pollen from some kindred flower. 
The calyx is not useless so soon as it ceases to envelope and 
protect tho flower, for the flowerstalk continues increasing in 
size until the seed is perfected, but ceases to do so in those plants 
whose calyces remain long green if these be removed. On the 
other hand, in the Poppy, and other flowers frogi which the 
calyx falls early, the flowerstalk does not subsequently enlarge. 
The corolla, or petals, with all their varied tints and perfumes, 
liave more important offices to perform than thus to delight the 
senses of mankind. Those bright colours and their perfumed 
honey serve to attract insects, which are the chief, and often 
essential, assistants of impregnation; and those petals, as observed 
by Linnseus, serve as wings, giving a motion, assisting to effect 
the same important process. But they have a still more essential 
office; for although they are absent from some plants, yet, in 
many plants, if removed from those possessing them before im¬ 
pregnation is completed, the fertilisation never takes place. They, 
therefore, perform in such cases an essential part in the vege¬ 
table economy ; and that they do so is testified by all the phe¬ 
nomena they exhibit. They turn to the sun, open only when it 
has a certain degree of power, and close at the setting of that 
luminary; their secretions are usually more odorous, more 
saccharine, and totally differing from those of tho other organs 
of plants; and in* the absence of light those secretions are not 
formed. 
The corolla is absent in some plants, the Willow for example. 
But where it exists it is not always short-lived ; for although in 
some, as the Cistus, the petals which open with the rising sun 
strew the border as it departs; so some, far from being ephe¬ 
meral, continue until the fruit is perfected. The duration of 
the petals, however, is intimately connected with the impregna¬ 
tion of the seed, for in most flowers they fade soon after this is 
completed ; and double flowers, in which it occurs not at all, are 
always longer enduring than single tlow'ers of the same species. 
Then, again, in some flow r ers they become green, and perform 
the functions of leaves after impregnation has been effected. A 
familiar example occurs in the Christmas Rose (Helleborus niger), 
the petals of which are white, but wdiich become green so soon 
as the seeds have somewhat increased in size, and the stamens 
and other organs connected with fertility have fallen off 
It is quite true that some fruit will not ripen if the part of 
the branch beyond is denuded of leaves; but this only shews 
that those fruits cannot advance when deprived of leaves as well 
as of calyx and corolla,—the only organs for elaborating the sap ; 
and there are some flowers, as the Daphne mezereon, autumn 
Crocus, and Sloe, that have their flowers perfected and passed 
away before the leaves have even appeared. 
That the petals in most plants perform an important part in 
elaborating the sap supplied to the fruit, is further proved by 
the flower being unable to bloom or to be fertile in an atmosphere 
deprived of its oxygen; and by their absorbing more of that 
gas, and evolving more carbonic acid than even a larger surface 
of leaves of the same plant. 
So essential is oxygen to the fertility of a flower, that, as we 
shall hereafter have occasion to state, the stamens of one plant 
absorb two hundred times their bulk of the gas at the time of 
impregnation; and Saussure found that double, or unfertile 
flowers, do not absorb so much oxygen as those which are 
productive. Tho following table shows the number of volumes 
of this gas inspired by one volume of the flowers and leaves :— 
By the By the 
flowers. leaves. 
Mathiola incana (Queen’s Stock), 6 r.M. ... 11-0 ... 4 0 
Ditto double-flowered. 7'7 
Polyanthes tuberosa (Tuberose), 9 a.m. ... 9'0 ... 3 0 
Ditto double-flowered. 7‘4 
Tropeeolum maius (Common Nasturtium), 
9 a.m . 8-5 ... 8-a 
Ditto double-flowered. 7‘25 
Brugmansia suaveolens, 10 a.m. 9 - 0 ... 5’0 
Passiflora serratifolia, 8 a.m. 18’5 ... 5'25 
Daucus carota (Carrot), 6 r.M. 8’S ... 7'3. 
Hibiscus speciosus, 7 A.M. 8'7 ... 5 1 
Hypericum caliciuum, 8 a.m. 7'5 ... 7‘5. 
Cucurbita melo-pepo (Pompion), male 
flowers, 7 a.m. 12 - 0 ... 6'7 
Ditto female ditto, 7 a.m. 3'5 
Lilium candidum (White Lily), 11 A.M.... 5'0 ... 2'5 
Typha latifolia (Cat’s-tail), 9 a.m. 9'S ... 4'25 
Castanea vesca (Chestnut), 4 r.M. 9T ... 8'1 
As the flowers inhale more oxygen than the leaves, so do they 
exhale more carbonic acid than these organs ; and, unlike leaves, 
they pour it forth not only during the night, but in the sun¬ 
light—at least, Dr. Priestley, Dr. Ingenhouz, and M. Saussure 
found this was done by the Rose, Marigold, and Honeysuckle. 
It is upon the oxygen combined with their parenchyma that 
the colour of a petal depends ; for sulphurous acid (the fume 
arising from a burning match), which has a most powerful 
affinity for oxygen, destroys the hue of all coloured flowers, 
though it leaves that of white flowers unchanged. Mr. Smith- 
son’s experiments, and those of M. Schubler, seem to indicate 
that the colouring matter of flowers and fruits is fundamentally 
blue—rendered red by acids or the addition of oxygen, or 
yellow by the presence of an alkali or the subtraction of oxygen. 
Mr. Smithson says, that the colouring matter of the Violet is 
the same in the ruddy tips of the Daisy, Geranium, blue 
Hyacinth, Hollyhock, Lavender, and various Plums, in the 
leaves of the Red Cabbage, and in the rind of the salmon Radish. 
The acid which causes the red tint seems to bo usually the 
carbonic. 
M. De Candolle refers to a memoire of MM. Schubler and Funk 
on the colours of flowers, which they divide into two grand series, 
corresponding to the two grand types of vegetable colour—yellow^ 
passing into red and white, but never into blue ; and blue pass¬ 
ing into red and white, but never into yellow. The former they 
call oxidated colours, the latter de-oxidated colours—green being 
the point of equilibrium between the two series. In the process, 
of oxidation you have yellow-green, yellow, orange-yellow, orange,, 
orange-red, red. In the process of de-oxidation you have green- 
blue, blue, violet-blue, violet., violet-red, red. To avoid the 
hypothesis of oxidation and de-oxidation, De Candolle denomi¬ 
nates the two series th exanihique and cyanique, indicative merely 
of the blue and yellow types. In the xanthic series we find 
Cactus, Mesembryanthemum, Aloe, Cytisus, Oxalis, Rosa, Ver- 
baseum, &c. In the cyanic series we find Campanula, Phlox,. 
Epilobium, Vinca, Scilla, Hyacinthus, &c. 
White is excluded from either series, because it is thought to. 
be doubtful whether it exists naturally in a pure state among 
vegetables. We do not see the ground of all this distrust, says 
Mr. Keith; why is not white to be called white ? Surely the 
corolla of Lilium candidum is a very good example of the colour 
in questiou. T he following changes of colour in quick succession 
are worthy of notice. The flower of Hibiscus mutabilis bursts 
open its integuments in the morning. Its corolla is then white; 
at mid-day it is flesh-coloured ; at sunset it is red. 
Black is also excluded with more apparent propriety, and yet 
it is to be found in the petals of some few flowers. Pelargonium 
tricolor and Vicia Faba will furnish examples. 
