"The Aphides form the food of very many insects. The larvae of the Ladybirds feed entirely

In conclusion, we should add that there are some valuable notes in the book to the young dissector and entomologist, and hints respecting nomenclature, arrangement of specimens, &c.

THE DRAGON-FLY.

They are also eaten by the larvæ of the swift and active Syrphida. Several Hymenoptera provision their nests with them, and others of the parasitic kind, such as the Chalcidica, Proctotrupidæ, Cynipidæ, and Ichneumonidæ. As to these last insects, the way in which they operate on the aphis is very remarkable. As may be inferred, from the size of the aphides on which they are parasitic, they are of very small dimensions; and one of these tiny creatures, when standing on the back of an aphis which it is about to wound, looks much like a rook perched on a sheep's back.

"When the fatal egg has been introduced under the skin of the aphis, the wounded insect, like the stricken hart, separates itself from its fellows, and passes to the under side of a leaf, and there fixes itself. Its body soon begins to swell, and at last becomes quite globular and horny, the change being caused by the death of the aphis and the rapid growth of the parasite within it. The Ichneumon passes rapidly through its changes, and in a short time assumes the perfect form, always with its head near the tail of its victim, pushes off the last two or three segments of the dead aphis, and makes its escape into the world. The dead and empty skins of such hapless aphides may be found plentifully towards the end of summer, sticking firmly to the leaf, and showing the round aperture through which the destroying parasite has crept. Sometimes there is a sort of contest between the aphis and the Ichneumon-fly, the former, however, having no more chance against its tiny foe than has a rabbit against a weasel. If the aphis have its beak deeply plunged into the bark, the Ichneumon-fly has an easy task, for the aphis can do nothing but kick and struggle while anchored to the spot by its proboscis, and all the Ichneumon-fly has to do is to make its deadly lunge. But if the aphis be wandering about the plant, the Ichneumon-fly has to walk about with it, and try first one side and then the other, until she can find an opportunity of depositing her egg." We give the following as a specimen of the general character of the woodcuts.

In the figure of the caterpillar of the Brimstonemoth the reader cannot fail to see an example of what has been well termed mimicry; for nothing could better represent the fragment of a twig of white-thorn than the stretched-out condition of the

the neighbourhood of Canterbury some pupæ of the Dragon-fly, and carefully watched the full development of the insect in my aquarium, I was so delighted at the beautiful sight, that I have endeavoured to give a description of it to the readers of SCIENCE-GOSSIP. After witnessing the metamorphosis of three of them, I happened to read the account given in SCIENCE-GOSSIP by F. Pollock, of his observations in Nov. 1868 (p. 245), and have witnessed most of the things there described. He remarks "that if the readers of SCIENCE-GOSSIP could be induced to watch, and be fortunate enough to witness the change of the pupa into the perfect Dragon-fly, they would be inclined to admit that few sights in nature are more wonderful."

No one for the first time witnessing the metamorphosis would (without being previously informed) for a moment think that the position of the insect was the natural one. They would most likely come to the conclusion I did, that it must fall and be injured, or killed. Under that impression I placed a sheet of paper beneath its head, to prevent such a mishap; but the moment the paper touched the head, the insect showed, by a peculiar movement, that it was annoyed, and endeavoured to avoid coming into contact with it. I soon found that the seemingly unnatural and helpless position was the proper one.

It is amusing to observe the care the pupa manifest in getting into a position where nothing can be in the way to obstruct their development. One in particular came up out of the water, and slowly climbed to the top of a reed I had placed in it. To keep it perpendicular, I had inserted a piece of wire about two inches from the top. This wire was in its way, and its lowly retraced its steps until it'arrived below it." It then placed itself in the usual position, and commenced lashing the body to and fro, at the same time violently jerking it, evidently to obtain a firm hold with its foot-claws on the reed, preparative to the change about to take place. When properly fixed, it became quite stationary for some time, and then a small opening became perceptible in the middle of the upper part of the thorax, and, gradually enlarging, the head of the fly was drawn slowly out and thrown backward until the head and thorax were clear of the pupa-case. When it had reached this position it remained quiet,

with the exception of an alternate stretching and contracting of its legs, as though trying their strength before the next move.

When sufficiently strong to bear the weight of the body, it gently turned itself backwards and laid hold on the head of the pupa-case. As soon as it was firmly fixed on it, the remainder of the abdomen dropped out of the case and hung outside it. Up to this time the wings had not begun to unfold; but as soon as the body was fixed and lengthened, then commenced the unfolding of the wings, presonting a very beautiful sight (especially if viewed through a pocket lens). The body was curved in such a way that the wings should not come in con. tact with it: at that time they were in so soft a state that to touch anything would injure their delicate tissues.

The creature appeared fully aware of this, as shown by its placing itself exactly in a position where none of the surrounding objects could touch it. The wings unfolded downwards, close together, quite soft, but when sufficiently dry and hardened, they gradually expanded, and showed by a quivering motion that they were ready for flight. Their unfolding perfectly took about twenty-five minutes.

I have had four pupa come out of one aquarium at different times, but up the same stem of the plant. It is interesting to see each of them place itself in the same position as its predecessors, and go through the movements, as though it had been the same insect performing over again.

My attention was drawn to four white thread-like filaments left attached to the empty and deserted pupa-case, two of which are fixed on the middle of the upper part of the thorax; their length drawn out of the corresponding part of the emerging insect. The other two were fixed one on each side, about a quarter of an inch farther down, below where the wing-cases open from the thorax. On placing them under the microscope, I found them to be trachea, and on further examining the empty case the trachea could casily be traced down each side to the breathing apparatus or spiracles at the tail. As the perfect insect will breathe by other spiracles, differently situated, this set of trachea is rendered useless and is withdrawn from the insect at its transformation. The opening out of which they are drawn is closed, so that they cannot be detected, as far as my observation went.

I have one pupa living, and shall watch it through the winter, as it is not likely to come out, now it is so late. I fed it at times with flies by placing them on a fine wire and gently moving it before the pupa's head. The latter quickly threw out its curiouslyformed mask, seized it, and conveyed it to its mouth.

They are very voracious, and will feed on almost any aquatic insects; as shrimps, beetles, small minnows, &c. I have sometimes given it a quantity of

PERHAPS Some of your correspondents could inform me whether the "test-scale” Podura can now be anywhere found. Every microscopist is familiar with the common species of Lepidocyrtus curvicollis, which supplies scales of the same general character, but by no means either so beautiful or so useful as tests. My own experience would incline me to think that the test-scale insect must be a distinct species, and not a variety of Lepidocyrtus. I have collected and examined great numbers of specimens from localities widely distant; but though some of these were passably clear in their markings, yet, when compared with the other in the microscope, the difference was instantly evident. They differ, in fact, as much as either differs, e.g., from Templetonia. The professional preparers, I find, can supply nothing except the common kind. I have heard it said, indeed, that the scale in question may be got from a bronze-coloured insect; but this is in direct contradiction to Mr. R. Beck's statement in his work on the microscope, in which he says that his scale is got from an insect of a dark leadcolour, and about of an inch long (p. 145). Mr. M'Intyre is, I presume, better informed on this subject than any one else; yet I have looked in vain among his communications for an explicit statement as to whether he has himself obtained this scale. In one of his papers in the Monthly Microscopical Journal he tells us that Lepidocyrtus curvicollis, if kept alive, will, as it grows old, develop the "test scale." But this he qualifies by adding the words, at least I think so,”— a highly important qualification, as it implies that, as a matter of fact, he has not found it to be so himself. Perhaps from his subsequent experience he could now say whether it is so, or whether the species is distinct, and can be found. Considering the number of persons interested in the clothing of these small deer, it certainly seems strange that this information is so difficult to be had. And if the species is distinct, and there was but one colony, it was a curious coincidence that Mr. Beck, who happened particularly to wish for them, should also be the person to find them.-S. L. B.

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HOW TO OBTAIN DIATOMS IN A STATE OF PURITY.-The American Journal of Microscopy recommends as the best plan "of collecting Diatoms in large quantities, to tie a thin fine piece of muslin

over the faucet of the hydrant in the evening, and allow a small stream of water to pass through it all night. In the morning take off the inuslin and rinse in a little water." The above plan, if tried in this country, would probably supply some of the freshwater forms, as Asterionella, Diatoma, Synedra, &c., in tolerable plenty; but I fear the experimenter would be liable to an action from the water company for waste!

WOODY STRUCTURE REPLACED BY PURE SILVER. -It is suggested that interesting metallic casts, showing the structure of wood, might be made by taking advantage of the deflagration of nitrate of silver on charcoal. When a crystal of nitrate of silver is placed on a piece of burning charcoal, it fuses and sinks into the pores of the wood; and as each atom of charcoal is replaced by one of silver, the structure of the wood is preserved. The modus operandi is thus described by Dr. Chandler :-" A crystal of nitrate is placed on a piece of charcoal, and a blowpipe flame directed upon the coal near to the crystal, to start the reaction. When deflagration commences, crystal after crystal may be alded; the nitrate fuses and passes down through The porous metal, already reduced, until it reaches the burning coal, where it is reduced." Lumps of silver, weighing an ounce or more, exhibiting the rings of wood in a most beautiful manner, have been thus prepared.

THE ANIMAL NATURE OF THE SPONGIADÆ.— Mr. H. Carter sends the following communication to Silliman's Journal, in which he says: "You will be glad to learn that I have confirmed all that Prof. J. Clark, of Boston, has stated about the sponge, and more too, confirmed by an examination of a marine calcarcous sponge. I have not only fed the sponge with indigo, and examined all at the same moment, but the sponge so fed was put into spirit directly afterwards, and now shows all the cells (monociliated) with the cilium attached, and the indigo still in the cells."

ARBORESCENT SILVER.-The very beautiful slides knowu to most microscopists under the above title are very easily produced, and as every preparation almost invariably shows some striking variation, some of the readers of SCIENCE-GOSSIP may be desirous of knowing the modus operandi. A drop of a very weak solution of nitrate of silver is placed on the centre of a slide, a small piece of the finest copper wire is then laid in the middle of the drop; crystallization at once commences, and when it has proceeded as far as the operator desires, the remain. ing nitrates of silver and copper must be poured off: this requires careful management. The best plan is to breathe on the slide, and then gently tilt it on one side this causes the fluid to drain away from the crystals. A little distilled water must then be allowed to flow from the opposite side: this will

wash away the nitrate of copper, and the slide will dry, and remain so. A small quantity of gum mixed with the distilled water will retain the crystals in their place (about three drops of the ordinary solution of gum in half an ounce of water is sufficient). The slide may now be dried and mounted in an asphalte cell. However, before doing so, it is better to remove the copper wire. This is best done by gently pushing one end of it: this will detach the crystals, and it can then be taken up by the aid of a small pair of forceps.-F. K.

GEOLOGY.

AT a recent meeting of the New York Lyceum of Natural History, Professor A. M. Edwards showed that the substance called " guano," used in the manufacture of artificial manures, is not, as is usually supposed, the accumulated droppings of birds, but a mud formed by the accumulation of the bodies of animals and plants, for the most part minute, and belonging to the group which Haeckel has collected into a new kingdom under the name of Protista. It was deposited along the ocean-floor, and eventually upheaved to the elevations in which its strata are now found. Subsequent changes so altered it that the organic matter was transformed to bitumen. The diatomaceæ, &c., found in guano occur as they would present themselves if deposited in water, and not as they would if they had passed through the stomachs of fish and birds.

IN the December number of the Geological Magazine, Mr. William Carruthers, F.R.S. (of the British Museum), has figured and described two new species of fossil coniferous fruits from the gaultbeds of Folkstone. He states one species to be allied to the existing Wellingtonia, and shows that they point to the existence of a coniferous vegetation on the high lands of the Upper Cretaceous period, which had a facies similar to that now existing on the mountains on the west of North America, between the thirtieth and fortieth parallels of latitude. No fossil referable to Sequoia has hitherto been found in strata older than the Gault, and here, on the first appearance of the genus, we find it is associated with pines of the same group that now flourish by its side in the New World.

DR. DUNCAN, F.R.S., has recently shown that a peculiar coral (Caryophyllia cylindracea), which has hitherto been regarded as peculiar, in the fossil condition, to the upper chalk strata, still lives in the deep-sea regions of Havannah, and off the I berian peninsula. It belongs to the group possessing only four cycles of septa in six systems.

A USEFUL ADDITION to our coal supplies has been made by the discovery, at Halesowen, near Birmingham, of a seam of coal fourteen feet thick. This fact controverts the theories hitherto held as

to the boundary of the coal-field in this direction, and of the impending exhaustion of the fuel-supply of the "Black Country," The seam lies at the depth of four hundred and twenty yards from the surface.

FOSSILS OF ARCTIC CIRCLE.-In the report of the Royal Society, printed in the Times of December 1st, mention is made of fossils recently brought from Greenland, which prove that the region within the Arctic Circle once enjoyed a tropical climate. Would any fellow-subscriber kindly give particulars?-E. P. F.

[The fossils referred to are of Miocene age, and principally plant-remains. Some hundreds of species have been brought to light from the Lignite beds, and their general character indicates that when they grew a warm climature prevailed in Greenland. It is more than probable that, at this time, no ice-cap existed at our North Pole.ED. S.-G.]

ZOOLOGY.

BATS. During the warm summer months it is pleasant to watch these wonderful little creatures seeking their food and sporting in the twilight; but who can tell where they hide themselves during the day, and throughout the winter? Having been much interested in some that came under my notice, I forward the following particulars.

About the beginning of August, in passing through a wood in this neighbourhood, I observed a poor little bat fluttering on the ground, apparently unable to rise. Supposing it to be a youug one injured in its fall from a nest, or a more mature one dazzled

by the brightness of the sun, I carefully caught it, when, on examination, I found a number of large brown ants fastened on to various parts of its body, sucking the blood from even the wings and eyes. Having been obliged to remove these with some force, I carried the little sufferer home in my umbrella, where he rode very comfortably suspended from the ribs by his hinder claws. He did not long survive his bleeding, being found dead next day.

On the night of the 19th of August my attention was drawn to a noise like a number of mice squeaking in my rainwater-butt, and on looking in I was surprised to find about twenty bats, some drowned in the water, some struggling to get out, and others clinging to the sides of the cask. I took them all out and laid them in the open air to dry themselves and fly away if they could. Next day all the live ones had disappeared, but I found there were some in the shoot or stack-pipe, which is about two inches in diameter, and conveys water from the roof to the cask. I took it down to see if there was any sort of nest in the top of it, but could find none. On shaking it over a large pan, no less than forty of

these little creatures fell out, many of them clinging to each other. Some appeared to be older than others, but all able to fly, and eat flies and sugar from the hand. Their bodies were about two inches in length, and their wings about six inches when extended, ears short, and teeth very sharp. There were numerous fleas in the fur, but I did not exmine them minutely.-G. M. M.

THE Magazine of Natural History for December has a note of great interest to ornithologists. Messrs. Sharp and Dresser describe two new species of European birds. One of them (Picus Lilfordi) is named after Lord Lilford, who shot it in Epirus. It is distinguished from an allied species by its crimson crown and barred rump. The other new species is from the British islands, and has been named Parus britannicus, or "Coal Titmouse." It differs from the continental examples by its olive-buff back. These species have hitherto been classed with others.

INSECTS IN WINTER.-We might naturally suppose that by the end of winter all those little birds which are solely supported by insect-food would find some difficulty in providing for their wants, having consumed, by their numbers and exertions, nearly all that store of provision which had been provided in the summer and deposited in safety; but I have found the stomachs of the Tree-creeper and the small Titmouse, even in February, quite filled with parts of coleopterous insects, which, by their activity and perseverance, they had been enabled to procure beneath the mosses, on the branches, and from the chinks in the bark of trees, where they had retired in autumn. Such plenty being procurable after the supply of so many

deficiency of food at any one period of the year. months, renders it apparent that there is no actual The small slugs and some few insects may be consumed by the severity of winter, but the larger portion of them are so constituted as to derive no injury from the inclemency of the season, but afford during many months provender to other creatures, multitudes yet remaining to continue their race and animate the air when the warm days of spring shall waken them to active life.-Journal of a Naturalist.

WORK FOR NATURALISTS.-The oyster-dredging at present carried on along our coasts affords facilities for investigating our marine zoology at moderate depths, which, I think, might be more fully taken advantage of. Those who have never spent a day with the oystermen have little idea of the almost inexhaustible supply of material which would be highly prized by the microscopist and student in Natural History, that is thrown overboard after every haul of the dredges. The great objection to accompanying the toilers in the deep" is that their avocation is principally carried

on in the winter under severe exposure. I had the good fortune to be out with them on a fine day in October, and found that even then, with a breeze from the north-east, it was cold enough for one accustomed to town-life. I was, however, amply repaid by a great store of marine forms, utterly inaccessible to me by other means. Anxious to have further supplies from time to time, I arranged with one of the boatmen, who readily consented to take charge of my basket of bottles and jars at any time, fill it with anything he might think of interest, and return it to me. Imagine my delight at finding in my first instalment a gorgeous specimen of the Bird's-foot starfish, Palmipes membranaceus, Retz. Those who have never seen any but dried specimens of this rare and beautiful echinoderm can form bnt a slight conception of its bright colouring when alive, as mine was when I received it. A starfish, which I take to be Ophiocoma Ballii, Thompson, was among the lot, with Comatula rosacea, Link, Cribella, and Solaster in abundance. I had also a great rarity in the crustaceans, Inachus leptochirus, Leach, probably dropped into one of my largest jars by my weather-beaten friend on account of the pearl-like tubercle on its thorax. In "Bell's British Crustacea" this species is said to be extremely rare. I would be glad to know if any Gossip has observed it, as I am inclined to believe, owing to its being liable to become encrusted with sponges, it has been overlooked. Good specimens of Hyas araneus and H. coarctatus, with other commoner species, were obtained. Two or three species of Nudibranchiata, and a number of conchiferous molluscs, which, with the polyzoa and sponges, made up a formidable list. Should any readers be tempted to try for themselves, I can guarantee ample work for winter evenings.-W. S., Belfast.

BOTANY.

HELICHRYSUM (Everlasting).—I grow a large quantity of this useful flower for winter decoration for myself and friends; and as many inquiries have been made as to the best method of treating it when cut, I am able to afford your readers some assistance. Wishing this year not to lose even the unexpanded buds, I gathered a quantity during the first week of this month, some of which were brought into the dining-room until otherwise disposed of. On subsequently removing them, I thought I perceived a partial separation of the petals, and it occurred to me that this effect, if really existing, must be due to the artificial temperature of the room. I immediately tested the matter by placing a number of buds before the fire, and as a result obtained as many full-blown flowers. Knowing, however, the tendency of the Helichrysum to close after it has been in bloom, I was not

satisfied with the experiment until I had ascertained that a night's exposure in the coldest room of the house failed to counteract the artificial treatment. Here, then, is a simple method by means of which a large stock of these elegant winter flowers may be utilized-it is now, in most situations, too late in the season to gather buds; but many of your readers may be in possession of some which were gathered green, and are now dry,-all that is necessary being to place them upon the fender before the fire; but in the case of those which are fresh-gathered, it is a better plan to suspend them, bud downward, by a worsted thread kept twirling, for by this arrangement the flower is at liberty to expand equally, and the stalk dries straight and rigid.— Wm. Tudor Mabley, Altrincham.

RARE OXFORDSHIRE PLANTS.-There have recently been complaints in SCIENCE GOSSIP that compilers of local floras do not take sufficient trouble to ascertain if rare plants, limited to certain localities, can still be found in those localities. A similar statement may, to some extent, be made respecting our standard British Floras. For example, I received in the spring a request from a corre spondent to gather Arabis turrita, which he said grew plentifully at Oxford. Now in the Floras of Bentham, Babington, and Hooker, this plant is mentioned as growing there, without even a hint that it may be extinct, or that it is more limited there than Senecio squalidus, which is very abundant. It was evidently from these standard works that my correspondent had obtained his information. I had visited Oxford several times, but had never seen the plant; hence I determined to make special inquiries. In Walker's "Flora of Oxfordshire" it is stated to have been found on Magdalen College walls, by Sibthorp and the Rev. Mr. White, in 1832; and the author informs us that it formerly grew in the Old Quadrangle. I visited the walls of the college this spring, but found no trace of it. I saw the curator of the Botanic Garden. He showed me a specimen cultivated in the garden; but he informed me that it had not been seen on the college walls for a number of years, having been overgrown by weeds. Last summer I gathered Salvia pratensis between Middleton Stoney and Ardley, the locality given in Walker's Flora; and this summer, after visiting several of the localities mentioned in the same Flora for Stachys germanica, I gathered it between Sturge's Castle and Enslow Bridge. Can any of your readers inform me if Thlaspi perfoliatum can still be found in the neighbourhood of Witney and Barford, as recorded by Walker to have been met with by Sibthorp and Hooker in 1818; or if Arabis turrita still grows at Cambridge, in Kent, and at Cleish Castle, Kinross, as stated in the Floras of Bentham and Babington?-4. French, Banbury.