decays, a very thin layer of vegetable earth is formed, which affords a scanty support for the roots of the next year's crop of mosses; and in process of time, soil is formed of sufficient depth for Draba verna, and other wall plants. A singular contrivance is conspicuous in one of our wild cresses (Cardamine impatiens), as well as in the balsums, and in touch-me-not (Impatiens Noli-me-tangere)-a native plant of the same genus. In all of these, when the seed is ripe, the valves which enclose it are so constructed, that by the influence of the sun's heat, they open with a sudden jerk, and throw the seeds to a considerable distance. The same effect is produced sooner, and with more force, when the ripe seed vessel is touched by the hand, or by any accidental waving of the leaves against it. Were we disposed to refine upon the final cause of this,-(a subject very ready to mislead), we might say, that this jerking of the seeds was contrived not only for their diffusion, but for their preservation from birds and insects,-since the instant that these should begin to devour them, the springs of the valves would be thrown into action, and the seeds scattered about before a single one could be secured for a meal. In the wood-sorrel, (Oxalis acetosella) as well as in the horned-sorrel (O. corniculata) the structure of these valves is very beautiful, but no description could do justice to it, not even with the aid of figures. The first, however, abounds in most woods, and the latter where it has been introduced as a flower, soon becomes, from the circumstance under consideration, a very troublesome weed. One of the most beautiful contrivances for the diffusion of seeds occurs in various species of violets. "The seeds of this order of plants are contained in a capsule of a single loculament, consisting, however, of three valves. To the inner-part of each of these valves the seeds are attached, and remain so for some time after the valves, in the process of ripening, have separated and stood open. The influence of the sun's heat, however, causes the sides of each valve to shrink and collapse, and in this state, the edges press firmly upon the seed, which, from being before apparently irregular in its arrangement, comes into a straight line. The seeds, it may be remarked, are not only extremely smooth, polished, and shining, but regularly egg-shaped; so that, when pressed upon the collapsing edges of the valve, it slides gradually down the sloping part of the seed, and throws it with a jerk to a considerable distance. There is another part in the contrivance of Providence, for the same purpose, in the violacea, worthy of remark. Before the seed is ripe, the capsule hangs in a drooping position, with the persisting calyx spread over it like an umbrella, to guard it from the rain and dews, which would retard the process of ripening: but no sooner is the ripening completed, than the capsule becomes upright with the calyx for a support. This upright position appears to be intended by Providence to give more effect to the valvular mechanism for scattering the seeds, as it thus gains a higher elevation (in some cases more than an inch) from which to project them; and this will give it, acccording to the laws of projectiles, a very considerable increase of horizontal extent. "Some ripe capsules of a fine variety of Viola tricolor, which I placed in a shallow pasteboard-box, in a drawer, were found to have projected their seeds to the distance of nearly two feet. From the elevation of a capsule, therefore, at the top of a tall plant, I should think these seeds might be projected twice or thrice that distance."* We MIGRATION OF EELS.-The migration of fish, which occurs at particular seasons, according to difference of species, may, during the present month, be remarked in the case of eels in streams where they abound; but as it usually takes place in the night, it seldom attracts attention. In cloudy weather, however, they often continue to run, as it is termed, during the morning. once, and only once, remarked this, about ten years ago, on the 13th of May. The river Clyde was embrowned at the time in consequence of a recent fall of rain, which may have partly induced them to continue running after sunrise. Their line of march, if we may call it so, was about a foot or more from the edge of the bank, with which they kept nearly parallel, and their column might be about six inches broad. The eels themselves were all of one size, about as thick as a crow-quill, and about three inches long. They kept so closely together, that there might be, we should suppose, some hundreds in a foot's length of the column. What was no less singular, the column itself appeared in its whole extent to be of uniform breadth, as if it had been regulated by the parallel lines of a mathematician. The length of this co lumn we had no means of ascertaining, but it must have been considerable, as we traced it for more than half a mile; and during several hours which we observed it, the run continued undiminished, and proceeded at a velocity, as nearly as we could estimate by the eye, of half * J. Rennie, in Mag. Nat. Hist. i. 380. a mile or more in the hour. The whole column must have consisted of countless millions of eels. SAP OF THE ROSE TREE.-From a plant of Rosa rubiflora at Hammersmith, with a stem 33 feet high, and 24 inches in diameter, when deprived of its branches, and the head sawed off, 29th July, 31 ounces of sap flowed in about a week, which, together with loss by evaporation, probably exceeded three pints. Chemical analysis gave the following ingredients : Oxalate of lime, Acetate of potass, Grains. 2.9 1.097 0.7 With respect to what Mr. Adams chooses to call extractive, I may be permitted to remark, that the term ought to be exploded altogether from vegetable chemistry, since it does not, like the terms gum, acid, or alkali, convey any distinct meaning, nor apply to a definite class of substances. The recent brilliant discoveries in vegetable chemistry, ought to put an end to this vague phraseology. POPULAR ERRORS RESPECTING BLIGHT.-The popular creed current among gardeners and farmers, and often met with in conversation, as well as in books, is, that the east wind, foggy weather, and other states of the air, produce, what is called blight, which means any thing that injures vegetation, but is particularly applied to destructive insects, and the parasite funguses, called by botanists, Entophyte Hypodermia. Now, it has been proved by observation and experiment, that all insects are regularly hatched from the eggs of parent insects, which are glued to plants or their roots the previous season, (as was shewn by specimens) and consequently cannot be spread about, nor increased by winds or fogs. It would be as correct to say, that a flock of geese was produced and spread about by blighting weather. The funguses called smut, and rust on corn, are in the same way produced from the seeds of former smut and rust, which being light, are spread about by the wind, but can no more be produced by it, than the corn itself. It is highly important, that the true causes of these evils should be known in order, that remedies for them may be devised, rather than passively accusing the weather, which cannot be controlled, if it were, as it cannot be, the cause of such blights.* FLOWERS. BY H. C. DEAKIN, AUTHOR OF "PORTRAITS OF THE DEAD," Baptized by dew and rainbow showers, E're the young world was in its prime- Ye blushed in Paradisal glades; Hung o'er her founts in glittering braids— *J. Rennie's Opening Lecture at King's College. |