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in such a manner as to shelter the young stems, buds, or fruit. They turn up, or they fall down, according as this purpose renders either change or position requisite. In the growth of corn, whenever the plant begins to shoot, the two upper leaves of the stalk join together, embrace the ear, and protect it till the pulp has acquired a certain degree of consistency. In some water plants, the flowering and fecundation are carried on within the stem, which afterwards opens to let loose the impregnated seed.* The pea or papilionaceous tribe, enclose the parts of fructification within a beautiful folding of the internal blossom, sometimes called, from its shape, the boat or keel; itself also protected under a penthouse formed by the external petals. This structure is very artificial; and what adds to the value of it, though it may diminish the curiosity, very general. It has also this farther advantage, (and it is an advantage strictly mechanical,) that all the blossoms turn their backs to the wind, whenever the gale blows strong enough to endanger the delicate parts upon which the seed depends. I have observed this a hundred times in a field of peas in blossom. It is an aptitude which results from the figure of the flower, and, as we have said, is strictly mechanical; as much so as the turning of a weather-board or tin cap upon the top of a chimney. Of the poppy, and of many similar species of flowers, the head, while it is growing, hangs down, a rigid curvature in the upper part of the stem giving to it that position; and in that position it is impenetrable by rain or moisture. When the head has acquired its size, and is ready to open, the stalk erects itself, for the purpose, as it should seem, of presenting the flower, and with the flower, the instruments of fructification, to the genial influence of the sun's rays. This always struck me as a curious property; and specifically as well as originally, provided for in the constitution of the plant; for, if the stem be only bent by the weight of the head, how comes it to straighten itself when the head is the heaviest? These instances show the attention of nature to this principal object, the safety and maturation of the parts upon which the seed depends.
In trees, especially in those which are natives of colder climates, this point is taken up earlier. Many of these trees (observe in particular the ash and the horse-chestnut) proapon this phenomenon, because, in the cold, leaves awaken later, and fall more easily asleep, notwithstanding the influence of light.” Vido Elements of the Philosophy of Plants by Decandolle. — Paxton.
* Phil. Trans. part ii. 1796; p. 502.
duce the embryos of the leaves and flowers in one year, and bring them to perfection the following. There is a winter therefore to be gotten over. Now what we are to remark is, how nature has prepared for the trials and severities of that season. These tender embryos are, in the first place, wrapped up with a compactness which no art can imitate; in which state they compose what we call the bud. This is not all. The bud itself is enclosed in scales; which scales are formed from the remains of past leaves, and the rudiments of future ones. Neither is this the whole. In the coldest climates a third preservative is added, by the bud having a coat of gum or resin, which, being congealed, resists the strongest frosts. On the approach of warm weather, this gum is softened, and ceases to be a hinderance to the expansion of the leaves and flowers. All this care is part of that system of provisions, which has for its object and consummation the production and perfecting of the seeds.
The seeds themselves are packed up in a capsule, a vessel composed of coats, (Pl. XXXIV. fig. 1,] which, compared with the rest of the flower, are strong and tough. From this vessel projects a.tube, through which tube the farina, or some subtile fecundating effluvium that issues from it, is admitted to the seed. And here also occurs a mechanical variety, accommodated to the different circumstances under which the same purpose is to be accomplished. In flowers which are erect, the pistil is shorter than the stamina; [Pl. XXXIV. fig. 2,) and the pollen, shed from the antheræ into the cup of the flower, is caught in its descent by the head of the pistil, called the stigma. But how is this managed when the flowers hang down, (as does the crown imperial, for instance,) and in which position the farina, in its fall, would be carried from the stigma, and not towards it? The relative length of the parts is now inverted. The pistil in these flowers is usually longer instead of shorter than the stamina, [Pl. XXXIV. fig. 3,] that its protruding summit may receive the pollen as it drops to the ground. In some cases (as in the nigella,) [Pl. XXXIV. fig. 4,) where the shafts of the pistils or styles are disproportionably long, they bend down their extremities upon the antheræ, that the necessary approxi mation may be effected.*
* Amongst the various means which nature has provided for the purpose of assisting the impregnation of plants, that afforded by the agency nf insects is not one of the least. In the spring and summer month
But (to pursue this great work in its progress) the impregnation, to which all this machinery relates, being completed, the other parts of the flower fade and drop off, whilst the gravid seed-vessel, on the contrary, proceeds to increase its bulk, always to a great, and in some species (in the gourd, for example, and melon,) to a surprising comparative size; assuming in different plants an incalculable variety of forms, but all evidently conducing to the security of the seed. By virtue of this process, so necessary but so diversified, we have the seed at length, in stone-fruits numerous species of these lively little beings may be seen in almost every expanded flower; and whether they are in search of honey, which is contained in the nectaries of many flowers, or whatever may be the object of their attraction, by being continually on the move, they, no doubt, further the dispersion of the pollen, and thus, in a great measure, contribute to the fertility of the plants they visit.
In many plants, as those which belong to the Linnæan class diæcia, where the stamens and pistils are in separate flowers, and those flowers situated on two separate plants of the same species, the operation of insects, or the efficacy of winds, is indispensably necessary to the perfecting the fruit, by transporting the pollen of the one to the stigma of the other.
Some plants, indeed, that have perfect, or united flowers, have the anthers so situated that it is almost impossible the pollen can, of stself, reach the stigma; in this case insects generally become the auxiliaries to the fertilization of the seed. An instance of this may be seen in the aristolochia clematitis. “According to Professor Willdenow, the flower of this plant is so formed, that the anthers of themselves cannot impregnate the stigma; but this important affair is devolved upon a particular species of tipula, (T. pennicornis.) The throat of the flower is lined with dense hair, pointing downward so as to form a kind of funnel, or entrance like that of some kinds of mouse-traps, through which the insects may easily enter but not return: several creep in, and, uneasy at their confinement, are constantly moving to and fro, and so deposit the pollen upon the stigma: but when the work intrusted to them is completed, and impregnation has taken place, the hair which prevented their escape shrinks, and adheres closely to the sides of the flower, and these little go-betweens of Flora at length leave their prison. A writer, however, in the Annual Medical Review (ii. 400,) doubts the accuracy of this fact, on the ground that he could never find T. pennicornis, though A. clematitis has produced fruit two years at Brompton.” Introduction to Entomology, by K'irby and Spence, vol. i. p. 298.
That the tipula pennicornis does enter the flowers of aristolochia clematitis, as recorded by Professor Willdenow, I can confidently affirm, from having observed them in great plenty in the inflated base of the corolla every year, for these last fifteen years, in the Oxford Botanic Garden, where the plant generally forms fruit. The first time I found this insect in the powers of the above species of aristolochia, was on the 12th of July, 1812, at Godstow, near Oxford, where the plant was then growing in a wild state near the ruins of the nunnery.
For the above observations the editor is indebted to an exenent dotanist, M. W. Baxter.--Paxton.
and nuts, incased in a strong shell, the shell itself enclosed in 'a pulp or husk, by which the seed within is, or hath been, fed; or, more generally, (as in grapes, oranges, and the numerous kinds of berries,) plunged over head in a glutinous sirup, contained within a skin or bladder: at other times (as in apples and pears) embedded in the heart of a firm Aeshy substance; or (as in strawberries) pricked into the surface of a soft pulp.
These and many other varieties exist in what we call fruits.* In pulse, and grain, and grasses; in trees, and shrubs, and flowers; the variety of the seed-vessels is incomputable. We have the seeds (as in the pea tribe) reg , ularly disposed in parchment pods, which, though soft and membranous, completely exclude the wet, even in the heaviest rains! the pod also, not seldom (as in the bean) lined with a fine down; at other times (as in the senna) distended like a blown bladder: or we have the seed enveloped in wool (as in the cotton plant,) lodged (as in pines) between the hard and compact scales of a cone, or barricadoed (as in the artichoke and thistle) with spikes
* From the conformation of fruits alone, one might be led, even withput experience, to suppose, that part of this provision was destined for the utilities of animals. As limited to the plant, the provision itself seems to go beyond its objoct. The flesh of an apple, the pulp of an orange, the meat of a plum, the fatness of the olive, appear to be more than sufficient for the nourishing of the seed or kernel. The event shows, that this redundancy, if it be one, ministers to the support and gratification of animal natures ; and when we observe a provision to be more than sufficient for one purpose, yet wanted for another purpose, it is not unfair to conclude, that both purposes were contemplated together. It savors this view of the subject to remark, that fruits are not (which they might have been) ready altogether, but that they ripen in succession throughout a great part of the year; some in summer; some in autumn: that some require the slow maturation of the winter, and supply the spring; also that the coldest fruits grow in the hottest places. Cucumbers, pinc-apples, melons, are the natural produce of warm climates, and contribute greatly, by their coolness, to the refreshment of the inha. bitants of those countries.
“ The eatable part of the cherry or peach first serves the purposes of perfecting the seed or kernel, by means of vessels passing through the stone, and which are very visible in a peach-stone. After the kernel is perfected, the stone becomes hard, and the vessels cease their functions. But the sul stance surrounding the stone is not then thrown away as useJess. That which was before only an instrument for perfecting the kernel now receives and retains to itself the whole of the sun's influence, and thereby becomes a grateful food to man. Also, what an evident mark of design is the stone protecting the kernel! The intervention of the stone prevents the second use from interfering with the first."
and prickles; in mushrooms, placed under a penthouse; in ferns, within slits in the back part of the leaf; or (which is the most general organization of all) we find them covered by strong, close tunicles, and attached to the stem according to an order appropriated to each plant, as is seen in the several kinds of grain, and of grasses.
In which enumeration, what we have first to notice is, anity of purpose under variety of expedients. Nothing can be more single than the design; more diversified than the means. Pellicles, shells, pulps, pods, husks, skin, scales, armed with thorns, are all employed in prosecuting the same intention. Secondly; we may observe, that, in all these cases, the purpose is fulfilled within a just and limited degree. We can perceive, that is the seeds of plants were more strongly guarded than they are, their greater security would interfere with other uses. Many species of animals would suffer, and many perish, if they could not obtain access to them. The plant would overrun the soil; or the seed be wasted for want of room to sow itself. It is sometimes as necessary to destroy particular species of plants, as it is at other times to encourage their growth. Here, as in many cases, a balance is to be maintained between opposite uses. The provisions for the preservation of seeds appear to be directed, chiefly, against the inconstancy of the elements, or the sweeping destruction of inclement seasons. The depredation of animals, and the injuries of accidental violence, are allowed for in the abundance of the increase. The result is, that out of the many thousand different plants which cover the earth, not a single species, perhaps, has been lost since the creation.
When nature has perfected her seeds, her next care is to disperse them. The seed cannot answer its purpose while it remains confined in the capsule. After the seeds therefore are ripened, the pericarpium opens to let them out: and the opening is not like an accidental bursting, but, for the most part, is according to a certain rule in each plant. What I have always thought very extraordinary; nuts and shells, which we can hardly crack with our teeth, divide and make way for the little tender sprout which proceeds from the kernel. Handling the nut, I could hardly conceive how the plantule was ever to get out of it. There are cases, it is said, in which the seed-vessel, by an elastic jerk at the moment of its explosion, casts the seed to a distance. We all however know, that many seeds (those of the most composite Powers, as of the thistle, dandelion, &c.) are endowed with what are not improperly called wings,