« ForrigeFortsæt »
BIRDS OF PASSAGE.
So the freed spirit flies!
Like the swallow from the skies.
Whither? wherefore doth it go?
That a void is left below.
BIRDS OF PASSAGE.
FROM THE SWEDISH, BY MARY HOWITT.
Behold the bird-legions,
"Where where are we going?
Who has for us sent?
'Tis thus unto God that they make their lament.
"We leave them with sadness,
Those rocks by the main;
By the wing of the breeze there
Now, now we must follow an unknown behest.
The leafy trees bowered o'er
The home of the dove;
The dew-drops were showered o'er
Now green fields are sering,
And with white hard-frost blossoms the meadows are strown.
Why tarry we longer
Here leave we a grave;
God wings to us gave,
Thus sang the bird-legions
And with songs of rejoicing the woodlands resound.
When life's hope shall fail thee,
Illumed by a sun that will set never more!
AUTUMNAL TINTS AND FALLING LEAVES. Many persons regard the autumnal colouring of the leaves of trees as the consequence of a diseased state of the foliage, which precedes its final decay ; others ascribe it to an alteration or diminution in the nutritive juices, which prepares the way for the fall of the leaf by paralysing the upper network. But although in general it is true that the fall of the leaves is preceded by their change of colour, yet there are many cases in which the leaves fall green ; and this fact must be considered of some importance, because if the change of colour in autumn foliage were a token of disease, and a commencement of death, we should expect the token to be constant throughout vegetation; but if it be a consequence or continuance of the regular action of the same agents which preside over the other functions of the plant, and thus exhibit a sign of life rather than a token of death, it is to be expected that such variations should occur.
It is well known that it is at the end of summer, or in the course of autumn, that the change in the colour of leaves is produced. However varied their tints may be, they, nevertheless, with few exceptions, come to shades of yellow or red, which are at this period the predominant colours of the landscape. This change is far from being sudden. In general the green colour in the leaf disappears gradually ; many leaves, however, as those of the acacia and apricot, begin to grow yellow here and there and in spots. In others, as the pear-tree, &c., spots of a beautiful green remain for a long time on the orange or yellow ground of the leaves. Some leaves, those of the sumach for instance, begin to change at their edges, and especially at the tip. The nerves, and the adjacent parts of the parenchyma, or pulp which connects the veins, seem to retain the green colour longest. It has been observed that leaves of the deepest green assume the red colour, and those whose green is pale, the yellow or yellowish tint. Most of the leaves, however, which become red, pass through the yellow as an intermediate tint, as in the sumach.
Light exerts a great influence upon the autumnal change in the colour of leaves; for in those which naturally overlap each other in part, the uncovered portion is always more
quickly and more deeply coloured than the rest. By entirely sheltering from the action of light either whole branches, or parts of leaves, it has been found that the change of colour is prevented. If an entire leaf is excluded from the light, it falls from the stem in the green state; if a portion of a leaf is shaded, the remaining part changes colour, while the shaded portion retains its original hue. If leaves, or portions of leaves, which are yellow before reddening, as those of the sumach, are placed in the dark, the leaves fall off yellow, or the covered part retains that colour, while the rest becomes red; thus proving the necessity of the action of light in all the stages of colouring.
It is well-known that the green parts of plants absorb oxygen during the night, and exhale à certain proportion of that gas when exposed to the action of the sun. It has been ascertained by a series of experiments that the leaves already coloured do not disengage oxygen gas by exposure to the sun's light : that when the leaves are either coloured in part, or at the point of changing colour, eren although they yet appear green to the eye, they from that moment cease to give out oxygen when exposed to the sun : that the leaves on arriving at the very point where the tendency to the autumnal colouring commences, continue to inspire oxygen gas during the night, and in a quantity always decreasing in proportion as the colouring advances : and hence it is to the fixation of the oxygen in the colouring matter of the leaf, that the change of tint is most probably owing
The green substance of the leaves possesses peculiar properties, and appears to be the seat of the modifications which take place in the appearance of the foliage. It has often been proved that if a green leaf is left in an acid, it becomes yellow or red, and that if it then be placed in an alkali the green colour is restored. So, on the other hand, if the yellow leaf of a tree be allowed to remain for some time in potash, or any other alkali, it becomes of a beautiful green, without experiencing any other sensible alteration.
If the reddened leaves of the sumach, or of the pear-tree, are treated with boiling alcohol, the liquor becomes of a fine blood-red, and by evaporation deposits a resinous substance, which becomes of a fine green by the actiou of alkalies. An
acid in this case restores the red colour. As the green is frequently seen to pass through the yellow hue before arriving at the red, we might naturally conclude that the latter is at a higher degree of oxygenation. Hence the autumnal change in the colour of the leaves may be owing to the successive fixation of new doses of oxygen, which continue to be absorbed without being exhaled. This would explain the phenomena presented by certain leaves, as those of the Arum bicolor, which exhibit the three orders, red, yellow, and green, at once, or those of the Tradescantia discolor, which present a beautiful red colour at their under surface, while the upper is green. Experiments made by M. Macaire prove that the same colouring principle that is found in the leaves may also be found in the flowers.
The red substance obtained from the coloured calyxes of Salvia splendens was rendered green by the alkalies, and became red a second time by the addition of an acid. The red principle obtained from the petals of red geranium, Bengal roses, asters, &c., followed the same rule; while from yellow flowers a yellow colouring matter was obtained, which was rendered green by alkalies. White flowers appear to contain a slight yellow substance, modified by some natural process. Reddish-blue flowers, such as those of the gilly-flower, yield a tint at first rosy, then purplish, and leaving a residuum of a fine violet colour. The flowers of the blue sweet violet give also a substance of similar hue, which, like the others, is rendered green by alkalies, and red by acids ; it is soluble in cold water, and might be kept in a state of powder, were it wished to preserve the colour of violets.-Chronicle of the Seasons.
On the first of the month pheasant-shooting commences, and hare-hunting a little later, though indeed for this last sport there seems to be no fixed time, as it often begins in September, the state of the fields regulating the date of its commencement. Fox-hunting properly begins on or near the thirteenth.