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two and sometimes three main arms, and when these go off in the direction of north-west and south-east, so as to expose the trunk of the tree on the one side to the prevalent winds from the south and the west, and on the other, to the less frequent but more violent winds from the north and east, the trunk is sometimes twisted nearly round.

FEBRUARY.

Effects of Snow on Vegetation.-It appears at first somewhat singular that the alpine plants, such as auriculas, some saxafrages, &c., should be of difficult culture in our climate, and are not unfrequently destroyed by our winters, whilst they flourish in their native snows; but it should be observed that, in the Alps, where, growing wild, they are throughout the winter covered with a complete coating of snow, which, from not being a rapid conductor of heat, is instrumental in the earth's not parting quickly with its warmth, in the same manner as a woollen garment prevents the escape of heat from the body, this protects them through the cold season; whereas, in our climate, these plants are exposed alternately to the severe influence of frost, unprotected by the snow, and to long-continued rains. The frost injuring the structure of the leaves, they become readily rotted by the wet; and although the plants are not often entirely killed, they are too much injured to ensure a good shew of bloom. It is necessary, for the cultivation of the finer sorts of auriculas, &c., to imitate, as far as possible, their native climate, by protecting them, in a frame or shed, both from the severe frosts and wet. It is, however, to be remarked, that our climate opposes another and a serious objection to the easy cultivation of this class of plants, arising from the great variation of temperature. Even during the winter months the plants frequently commence growing before the spring arrives, and thus are rendered more obnoxious to the succeeding frosts; and, in addition, the strength of the plants (which should be reserved for the great effort to be made in the spring) is exhausted before its due seasonwhilst, in the Alps, they lie entirely dormant until the sun at once melts the snow, and calls them into life and blossom. To prevent the plant growing out of its season, it is found best to place the pots in a part of the garden exposed to a northern or western aspect.

Nest of the House Sparrow.-The variations of instinct manifested by animals in certain circumstances is well exemplified in the house sparrow (Fringilla domestica). This bird usually selects for her nest a hole in a wall, or under the eaves of a house, but sometimes makes choice of a very different situation. In all cases, the builder pays more attention to warmth than neatness; and when the nest hole is furnished with a sufficient roof, the sparrow does little more than toss in a bundle of loose straw for a foundation, over which a bed of feathers is laid in a similar careless manner. But though the materials are not nicely interwoven and rounded, as is done by the goldfinch, the wren, and many other birds, the sparrow contrives to have her cradle-chamber soft, snug, and comfortable.

In the suburbs of London, and some other places, the sparrow seems to be partial to trees; though not, as might be supposed from its usual habits, to such as could afford a canopy of thick boughs, to roof in its nest; for it most commonly pitches on a high and exposed branch, as if it were more anxious to be out of the reach of cats than of cold winds. A canopy, however, is never dispensed with; but in the latter case the bird is at the trouble of constructing one, of straw, inartificially piled upon the roof. The entrance is by a side passage, and partakes of the same character of rough workmanship which prevails in other parts of the structure.

During the last spring (1829) we particularly examined the structure of a sparrow's nest built amongst ivy leaves on the wall of a house at Southend, Lewisham, Kent, which was, of course, in circumstances considerably different from either of the preceding. The thick clustering of the ivy leaves above the nest was not, however, deemed a sufficiently warm coping, and a roof of straw had been constructed, though much more slight than in nests built on the exposed branches of trees.

MARCH.

Swarms of Butterflies. An immense swarm of butterflies, of the species called the Painted Lady (Papilio cardui, Linn.), forming a column of from ten to fifteen feet broad, was observed in the district of Grandson, Canton de Vaud, in 1828. They traversed the country with great rapidity, from north to south, all flying onwards, low, equally and closely together, and not turning from their course on the approach of other objects. The fact is the more singular, as the caterpillars of the Vanessa cardui are not gregarious, but are solitary from the moment they are hatched. Professor Bonelli of Turin, however, observed a similar flight of the same species of butterflies in the end of the March preceding their appearance at Grandson. Their flight was also directed from south to north, and their numbers were immense. At night the flowers were literally covered with them. Towards the 29th of March their numbers diminished, but even in June a few still continued. They have been traced from Coni, Raconni, Susa, &c. A similar flight of butterflies is recorded, at the end of the last century, by M. Loche, in the Memoirs of the Academy of Turin. During the whole season, those butterflies, as well as their larvæ, were very abundant, and more beautiful than usual*.

Supposed Identity of the Whitebait and Shad.-The whitebait has hitherto been generally considered as the young of the shad, but this doctrine has been recently combated by Mr. William Yarrell, F.L.S., who was led to investigate this subject by observing the early appearance (March) of whitebait in a fishmonger's shop; and, knowing that shads, which they were supposed to be, did not make their appearance till much later (May), he took up and per

la Société de Phys. et d'Hist. Nat, de Genève,

+ Zool. Journ., No. XIV.

severed in a course of investigation which lasted from March to August, 1828. The specific distinction between the two fishes, on which he relies as of the greatest value, is the difference of their anatomical character, and especially in their number of vertebræ. "The number of vertebræ in the shad," he says, "of whatever size the specimen may be, is invariably fifty-five; the number in the whitebait is uniformly fifty-six; and even in a fish of two inches, with the assistance of a lens, this exact number may be distinctly made out."

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Indications of Spring. The following table (which we extract from the "Magazine of Natural History") is the register of more than sixty years' observations, made by Robert Marsham, Esq., at Stratton-Hall, which is situated rearly in the centre of Norfolk. The earliest date recorded is the year 1735, and the latest observation appears in 1800. The least variations are in the time of the appearance of the migratory birds, and the hatching of young rooks. The greatest range is in the blossoming of the turnip, the "appearance of the yellow butterfly, and the singing of the thrush.

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Effects of Water on the form of Leaves.-The very striking difference which circumstances produce in the form of vegetables is prettily illustrated in the instance of the water crow-foot (Ranun

culus aquatilis), whose white blossoms may be seen sprinkled over the waters of every pond, or slow running stream, during the summer months. It is known that the bottom of the stems of particular plants, in certain situations, change to a bulbous structure, of which change the Timothy grass (Phleum) and fox-tail grass (Alopecurus) are examples. Before this change of structure was discovered (by M. Leers, if we mistake not), botanists frequently described the same grass under different names, as in the instance of the Phleum pratense and Alopecurus geniculatus. The beech, the sycamore, and still more the ash, also illustrate the fact, by producing in stiff dry soils only a few stunted roots; whereas, in a deep, rich, free soil, the minutest fibre expands with facility, and innumerable fibres are thus developed.-(DU HAMEL, Physique des Arbres, i. 82.)

The water crow-foot exemplifies on the same plant the effect of difference in situation, analogous to those varieties in soil. The leaves which are under water are minutely divided into thread-like leaflets, while those which float on the surface of the water are broad, rounded, and entire.

Unusual abundance of the Lackey Moth.-Last summer was remarkable for the extraordinary numbers of the caterpillars of the lackey moth (Lasiocampa neustria), whose eggs were figured in the Companion to the Almanac for 1829, page 29. Every hedge and orchard in the vicinity of London swarmed with them, and many trees were in consequence stripped of their leaves. Four or five summers ago we remember a similar abundance of the caterpillars of the small Ermine Moth (Yponomeuta padella, LATREILLE). The causes of such extraordinary fluctuations are, in the present state of our knowledge, altogether inexplicable.

JUNE.

The Hop Fly-It is during this month that the hop plant is liable to be infested with the insect well known under the name of the hop-fly (Aphis humuli, LINN.). The fecundity of this insect is altogether incalculable. We have counted more than a thousand on a single leaf, and supposing that an individual plant bears a thousand leaves (a small estimate) it may have to give nourishment from its juices to a million of aphides. Small as the insect is, so great a number require constant food, that it is surprising a single hop-plant escapes entire destruction; but though the plantations are often, from this cause, prematurely tinged with an autumnal-like brown, they usually partially recover about the end of July and take a renewed growth, for the aphides disappear at this time. Their extraordinary numbers will be less wondered at when it is recollected that M. Réaumur proved by experiment, that one aphis may be the progenitor of 5,904,900,000 descendants, and he further supposes that in one year there may be twenty generations. They are, in fact, endowed with a principle of fecundity peculiar to themselves, and not possessed by any other animal,—being

at one time viviparous, and at another oviparous. The same genus of insects is extensively destructive also to beans, peas, and many species of flowers. Our geraniums and monthly rose-trees are frequently infested with them; and our China-asters, in the early stage of growth, are in many cases so weakened by them as to be prevented from blowing.

Vulgar error respecting the Fly called the Horse-stinger.-The prejudices of the common people frequently originate in the most far-fetched analogies and inaccurate observations; but even among the better-informed classes, whole tribes of creatures altogether harmless are regarded with horror, and shrunk from as if they were endowed with the most formidable means of injuring.

The larger dragon flies (Libellulina, MAC LEAY) are in England universally called horse-stingers, on the supposition that they have a propensity to sting horses, and (it may be presumed) any other animal which may irritate them. But not one of this tribe of insects is furnished with a sting. They have, however, a pair of most formidable-looking jaws or mandibles, though even these are not strong enough to inflict any injury on the larger animals, and are only employed to crush a fly, or to wing a moth or a butterfly.

JULY.

Different Colours of the Eggs of Birds.—It is a remarkable fact in the economy of Nature, that of those birds whose nests are the most liable to discovery, and whose eggs are most exposed to observation from the form of the nests, the eggs are of that colour which is the least différent from the surrounding objects; whilst those birds whose eggs are of a bright and positive colour, hide their nests in the hollows of trees, or never quit them, excepting in the night, or sit immediately that they have laid one or two eggs. It is also to be observed that of those species which build an exposed nest, and the females of which alone perform the duty of incubation, the colour of the female is much less bright than that of the male, and more in harmony with the objects by which she is surrounded during the period in which she sits upon her eggs. It would seem, therefore, that those birds which lay a brightly-coloured egg have the instinct to make a close nest, or to place it in the least exposed situations; while those which lay a sober-coloured egg are less solicitous to conceal it from the notice of their enemies. M. Gloger, a German naturalist, has paid great attention to this curious circumstance, and has very recently published an elaborate memoir, in a work printed at Berlin, (Verhandlungen der Gesellschaft naturforschender Freunde in Berlin, tom. i., 1829,) in which he notices the habits of all the species of birds indigenous to Germany, in confirmation of the theory. Our limits will not allow us to notice the particular species which he enumerates; but it may be sufficient to excite attention to this subject, to mention, that the birds which lay an egg perfectly white (the most attractive of colours) make their nests in holes of the earth, and cavities of trees, such as the kingfisher and the woodpecker, or construct

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