368 WHAT IS CHLOROPHYLL? "The rose has but a summer reign, The daisy never dies ;" and though it first makes its appearance in the merry springtime, and is truly a child of the early year, it lingers on to become a precious ornament of our scanty autumn wreaths. Sweet flower of song!-dearer to the poet than even lily or violet-who does not remember, and remembering feel, all the pathos of the dying exclamation of poor Keats,—“I feel the daisies already growing over me!" They heighten the commonest and cheer the saddest corners of the earth, and are ever ready, in their simple loveliness, to awaken thoughts of grateful tenderness and love "So glad am I when in the daisy's presence, That I am fain to do it reverence." To what do the leaves, now changing their hues so rapidly, and varying through all the tints of purple, brown, and yellow, -to what do they owe their normal colour, the fresh, vivid, beautiful green? To a substance called chlorophyll-(xλwgds, green, and puλλov, a leaf). Well, what is chlorophyll? The colouring matter of plants, which, accompanied by grains of starch, floats like very minute seeds in the fluid of their cells. In some respects it is analogous to wax ; it will not dissolve in water, but is easily affected by ether or alcohol. Chlorophyll is dependent upon the action of light, if not for its formation, at all events for its development. Keep a plant in a dark room or cellar, and it will become blanched SOME RECENT EXPERIMENTS. 369 and sickly; the colouring matter dries up, and the white, wan tissue of the leaf is all that survives. The more a plant is exposed to the light, the deeper will be its green. In a shrubbery you may notice that the brown leaves of any particular evergreen or bush, if so situated as to lose the direct action of the sun's rays, will soon change colour. Instead of their natural brightness of tint, they assume a sickly greenish-yellow hue, and are said to be suffering from chlorosis. The formation of the chlorophyll is obstructed, or takes place too slowly. Of course, this peculiar condition will frequently arise from bad soil, or a long continuance of damp weather; but it is also the result of a want of light. It should be observed that young leaves are always of a lighter green than old; simply because the latter have been exposed for a longer time to the light. And so the leaf goes on deepening and deepening in colour, until the sad days of autumn come, and the green gives way to yellow and brown and red, owing to the influence of the changing season on the chlorophyll of the plant. In reference to this interesting subject,—which deserves to be more closely investigated,—we may place before the reader the results of certain recent experiments.* MM. Prillieux, Brongniart, and Roze (Comptes Rendus, Jan. 3 and 17) have made some important observations on the apparently spontaneous movements of the grains of chlorophyll within the leaves of plants. These had been observed by Böhm to congregate under the direct action of the sun; * As recorded, in a condensed form, in The Academy (Feb. 12, 1870), pp. 131, 132. 370 A PLASMIC ILLUSION DETECTED. Famitzin, confirmed by Borodine, had also recorded very marked movements in the leaves of a moss under the influence of light. This class of plants offer great facilities for these observations, inasmuch as the movements can be observed in them under the microscope without dissection. M. Prillieux kept a moss in the dark for several days, when the cells presented the appearance of a green network, between the meshes of which was a clear transparent ground. All the grains of chlorophyll were applied to the walls which separate the cells from one another; there were none on the upper or under walls which form the surfaces of the leaf. Under the influence of light the grains change their position from the lateral to the superficial walls; under favourable circumstances this change takes place in about a quarter of an hour. On attaining their new position, the grains do not remain absolutely immovable, but continually approach and separate from one another. If again darkened, they leave their new position and return to the lateral walls. Artificial light produces the same effect as daylight. M. Brongniart further observed that this movement of the chlorophyll, under the influence of light, does not consist in the change of position of isolated grains, but of masses of net-work, each containing a certain number of grains. In addition, M. E. Roze states that, besides the grains of chlorophyll which coat the walls of the cell, each cell is lined with a transparent mucous plasma formed of very fine threads, the extremities of which unite together the grains of chlorophyll. This protoplasm exhibits, under a high magnifying power, a very slow motion, THE OLD FAMILIAR FLOWERS. 371 and carries the grains of chlorophyll along with it. M. Roze believes, therefore, that the motion is a plasmic one, the protoplasm being the vital and animating part of the cell. CARNATIONS AND PINKS. Among the latest flowers of the autumnal garden are those old favourites, the "July-flowers," or Carnations, which, because they were "fair and sweet and medicinal," Jeremy Taylor preferred to "the prettiest tulips, that are good for nothing." I remember a time when they were among the best-prized ornaments of our parterres, and very delicious it was to inhale the balmy breath that rose into the warm air of an autumn evening from rich masses of carnations and pinks. The carnations were also called-sub consule Planco-in the merry days when I haunted the green lanes of a pretty Devonshire village, carnations, and clove July-flowers or gilliflowers; and an ancient name for the pink was that of sops-in-wine, because they were infused in the wine-cups of our much-drinking So Drayton says :— ancestors. "Bring hither the pink and purple columbine, Bring coronations, and sops-in-wine, Worn of paramours." The same poet alludes to them under their more modern appellations : "The brave carnation, then, of sweet and sovereign power (So of his colour called, although a July flower), With the other of his kind, the speckled and the pale ;-- Of sweetness, yet in scents as various as in sorts." 372 THE BEAUTY OF THE GARDEN. The scientific name of this beautiful family of plants, whose rich dyes are not less conspicuous than their Sabæan odours, is Dianthus, or "Flower of God." They form a genus of the FIG. 79-"When I haunted the green lanes of a Devonshire village." natural order Carophyllacea; the calyx is tubular, and fivetoothed; there are five petals, which at the throat of the |