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less bird; linger, and his eagerness to attract your attention will become almost comic. Make a careful search around, and if you are gifted with keen eyes you will soon discover the cause of the poor bird's uneasiness, for in some tuft of coarse rushes just raised above ground, lie four or five wee birdies, whose welfare is watched most jealously by "blackcap" and his spouse.

This habit of luring the spectator away from the neighbourhood of its nest is by no means peculiar to the "Riverside Bunting." I have seen instances of the same in the Lapwing (V. cristatus), common Partridge (P. cinerea), Skylark (A. arvensis), &c. On the 1st of last July, when walking near a hedge in a field, a beautiful male Yellow-hammer (Emberiza citrinella) flew out, and, pitching just in front of me, began to limp, reel, and tumble in the most curious fashion. Disregarding the pretty creature's deceptive evolutions, I searched the bushes close by, and soon found its badly-concealed nest, containing four imperfectly-fledged young.

The nest of the Black-headed Bunting is, as I said before, placed very near the ground, and is composed of coarse grass, bits of reed, stems of plants, and lined with fine roots and hair. The eggs are four or five in number, of a reddish brown, scrawled and streaked in true bunting style with dark purplebrown.

At the approach of winter the "Riverside Bunt" ing" leaves its watery haunts, and in severe weather is often seen round barns and farm-yards, feeding with corn-buntings, greenfinches, house-sparrows, chaffinches, and other grain-devouring birds. Kingston, Abingdon.

SPIDERS' WEBS AND SPINNERETS.

HA

AVING read with interest in some recent numbers of SCIENCE-GOSSIP Mr. Underhill's observations on the spinnerets of spiders and their webs, and the subsequent remarks of Mr. Stratham, who quotes a letter from Mr. Black wall, the great authority on such matters, I wish, as some years ago I paid considerable attention to the life-history and anatomy of these creatures, to add my little contri. bution to the general stock of knowledge on such matters.

As my attention was principally directed to the Epeira, and as Mr. Blackwall says that he would much like to know what Mr. Underhill has to say relative to their snares, I will commence by stating my views on this subject. To make myself understood, I must commence at the A, B, C of the matter. The Epeira have three pairs of spinnerets; the two larger pair are placed opposite each other, so as to form the bastions, as it were, of a square redoubt, inclosed within which are the other two spinnerets, or third pair. Each of these pairs of spinnerets are provided with a vast number of spinning tubuli,

which in each pair differ considerably in number, calibre, and arrangement with regard to each other; and in each pair there are from one to four or five tubuli of much greater size than the others. In short, the tubuli of each pair of spinnerets differ considerably from those of the others. The two exterior pairs of spinnerets are furnished with precisely similar glands, though their tubuli differ; whilst the interior and smaller pair are provided with a totally different kind. The question is, How are these spinnerets used? I have in vain tried to determine this by ocular demonstration, and indeed I fancy it is impossible to do so, though Mr. Underhill states that one kind of thread results from one pair of spinnerets,and the other kind from another. My explanation of the matter is a merely theoretical one.

Fig. 26. Web of Spider, covered with viscid globules.

The Epeira has various things to do-to make its web, consisting of scaffold-lines attached to bushes, and converging afterwards by radial lines to a common centre, which are very strong, elastic, and dry; to form on these the spiral and practically concentric lines of the web, which are furnished throughout with viscid drops, a species of birdlime, to detain the prey, which, when thus caught, is swathed round with lightning-like rapidity, in a mummy-like shroud by a secretion shot out from the spinnerets.

In old natural-history books it was stated that the Spider, having spun its web, went over it again, and added the viscid drops; and this was always quoted as a specimen of its perseverance and industry; the late Mr. Richard Beck, however, exploded this fallacy by taking his microscope into his garden, and watching an Epeira making its web, when he saw that the compound line, after its emission, ran of itself into dots by molecular attraction. So far so

good; but I have every reason to believe that Mr. Beck had only arrived at half the truth; for on examining a web, I find that the concentric lines run through the viscid drops, which appear like so many beads strung on a thread; this of course would not be the case if a single viscid line ran by molecular attraction into drops. Moreover, the thread itself is dry, whilst the drops are viscid.

I therefore infer that two pairs of spinnerets with different kinds of glands are employed simultaneously in forming the concentric lines; viz., one of the exterior pairs to make the thread, which is varnished by a secretion from the inner pair, as it runs out, and which secretion it is that runs into dots, just as saliva will on a hair passed between the moistened lips. There is plenty of work for the other pair of exterior spinnerets in forming the radial lines, and in swathing round the creature's prey, though possibly for this last operation the whole battery of spinnerets may be used. I have spoken of the spinnerets as employed always in pairs; but it seems to me that this is doubtful, my own impression being that one, as a general rule, is held in reserve, to be employed when the other is exhausted, which I know from observation is often the case.

So much for the Epeira web, and now for Ciniflo atrox. I have never had the pleasure of its acquaintance; but hunting for it, after having read Mr. Underhill's paper, I came across a web in a hole of an old elm-tree, which I fancied must be the web of this species. On examination, however, under the microscope, it evidently was not so; and as I have in vain tried to get a sight of the architect, I shall be obliged to Mr. Underhill, or any one else, who will tell me the name of the species. At all events, its web is most curious and interesting; it is not geometrical, and each thread is thickly furnished with dots grouped together in grape-like bunches. No single line could possibly fall into such groups by molecular attraction, and I therefore consider it a further proof of my theory, that two pairs of spinnerets, with different glands, are employed simultaneously in forming the web. That the glands become exhausted by constant use is evident, as I have abstracted their web for the purpose of mount. ing it each morning, and it has invariably been renewed during the night; but on each successive morning the characteristic conglomeration of dots becomes smaller and fewer in number.

CAPT. LANG.

ON PREPARING ALGE FOR THE
MICROSCOPE.

HITHERTO my directions have been devoted

exclusively to the process of mounting alga on paper for the herbarium; but 1 will now proceed to describe my own method of preparing plants for the microscopists, and especially for those persons whose

business it is to mount specimens in Canada balsam between circular glasses from 3 in. to 2 in. diameter (either for the gas lantern or gas microscope), and for the ordinary 3 by 1 glasses for the table microscope. I mention Canada balsam as the medium for mounting algae as the best with which I am acquainted for preserving the colour and structure of the plants, and also for rendering them transparent.

In the first place, I must observe, that with the exception of the fuci, and some few of the coriaceous and leathery-like red plants, I never put seaweeds into fresh water, nor, when dried, into spirit of any kind. In the first, they are apt to decompose or change colour, and in the latter they generally lose all their natural colour, which no amount of staining can satisfactorily restore. Colour can, of course, be imparted to some of these marine plants, but not the tint of their original endochrome. I have mounted specimens of all the British fuci, but the structure of most of them is so dense and stick-like that it is almost impossible to get the balsam to penetrate them sufficiently to obtain any amount of transparency; but with the exception of these coarse rock weeds, I have mounted specimens of every known British marine alga in Canada balsam, not one of which has lost colour or suffered injury to its structure in any perceptible degree; and the process by means of which I prepared them for the balsam, I will now describe.

Having obtained my specimens, either fresh from the sea, or floated off paper on which they may have previously been mounted, I immerse them, one at a time, in clear, strained sea-water, and wash and clean them well, until, with the aid of a lens, I can discover neither dirt nor parasite on any portion of either side of the plants. This is, with some of the delicate red weeds, occasionally a troublesome ope. ration, for several species of minute zoophytes adhere very firmly to their fronds. However, by pressing a finger of the left hand on the base of the specimen, as it lies in the water, and holding it firmly in the mounting dish, I scrape the zoophytes away with a penknife, which must not be too sharp, and must be applied very gently. As the calcareous particles are detached from the plant, they float away in the water, and an old worn tooth-brush may then be employed to clear off loose bits of shell or sand, and a final washing in clean water completes this portion of the work.

Some of the gelatinous species of green, olive, and red seaweeds may be very satisfactorily mounted on glass while they are floating in the water, especially when large specimens for the gas lantern are required. When this is desired, say on a circle of 3 in., the glass should be washed clean, and then slipped quickly under the floating weed. Then gently raise the glass at one side until the base of the plant is caught on its surface, and then, by means of a smooth-pointed style of ivory, or a

porcupine's quill, display the branches of the weed in a natural manner, as the glass is cautiously drawn out of the water. Put it in a slanting position for a few minutes to drain, and then, having placed the

glass on a piece of blotting paper, cover the specimen

with a smooth piece of fine cambric, and then place a piece of blotter on the cambric, employing very gentle pressure, while another specimen is being prepared for another glass. Change the blottingpaper frequently, but use very little pressure, and do not remove the cambric until the plant is quite dry, which it will be in a couple of days. Remove the cambric very gently, and clean away the saline particles which remain on the glass in all directions by means of a finely-cut stump, and finally brush gently with a camel's-hair pencil around and between the branches of the plant, but touch the specimen as little as possible. I have kept plants so prepared on glass wrapped up in tissue-paper for years before they were mounted in balsam. I need hardly say that fresh-water algae must be cleaned and mounted in fresh water, whether they are to be mounted on glass or paper. Unless the manipulator be skilful in laying on the balsam and placing the glass cover on his specimens, he had better commit his preparations to the care of Messrs. Topping & Son, Mr. J. Bond, or Mr. Norman, the addresses of whom may be obtained from Messrs. Carpenter & Westley, 24, Regent-street, London.

When algae are required to be prepared loose and dry, my plan is first to provide myself with small sheets of fine cartridge-paper, and having soaked them well in pure salad oil, let them drain well, and afterwards dry them in the sun for a day or two. The specimens, which must be cleaned and washed as already described, may then be mounted on the oiled papers in the clearly-strained sea or fresh water, and covered with cambric and blotter, and subjected to pressure, and the oftener the blottingpaper is changed the sooner the plants will be ready. Upon removing the cambric cover, the specimens will be found adhering either to it or the oiled paper, from either of which they may be easily removed by means of the fingers or a pair of forceps. They may then be mounted in balsam at once, or placed flat between sheets of writing-paper, and if kept from the light, will retain their exact condition and colour for years.

In preparing seaweeds for mounting in Canada balsam, it is of course always desirable to have specimens fresh from the sea; but when these are not obtainable, nearly every mounted plant, with the exception of the gelatinous species, and a few others among the red subdivision, may be removed from paper by soaking them well in water, and employing a porcupine's quill to detach them-a process which requires time, careful manipulation, and considerable patience. W. H. GRATTANN.

1 ON WHITE AND OTHER VARIETIES OF FLOWERS.

THE following species have been found by me of a clear white, wholly untinged with colour, though they are distinctly, some very strongly, coloured in their ordinary state :-Cardamine pratensis, frequently; Viola odorata, known, of course, to every one; Malva moschata, once only, near Oswestry; Epilobium montanum, seldom; Campanula rotundifolia, occasionally; Erica tetralix, I have white specimens, wild, but the locality, though certainly British, is unknown; Solanum Dulcamara, Tunbridge Wells, and near Oxford; Digitalis purpurea, in Denbighshire; Pedicularis sylvatica, on Tunbridge Wells Common; Scutellaria galericulata, around Abingdon; Polygonum persicaria, rarely, Colchicum autumnale, in Sweeney meadows, near Oswestry. None of the many Floras I have examined speak of a white variety of this plant. Flowers of pure white, however, occur abundantly among the profusion of others of ordinary hue which constitute the autumnal adornment of these lowlying fields, but are not distinguished from them, so far as I could trace, by any other characters; Agraphis nutans, occasionally. Other variations in tint which I have noted are of some interest. Anemone nemorosa, as it usually occurs, is white, but with a strongly-marked purplish exterior, as if indicating a union between dark sepals and uncoloured petals. The petals are, however, in reality, absent. The purple tint is, of course, a compound of red and blue. I have found the flower vary in the one direction into the total absence of the purple tinge, and, consequently, to perfect whiteness, and on the other to a development of the purple, that hue extending even into the interior of the perianth. This latter variation occurs in numerous degrees, more or less removed from the original point of departure, and taking two separate courses, accordingly as the red or blue constituent of the purple becomes gradually predominant, ending in the production on the one side of a rich pink flower from which all trace of blue intermixture is absent, and on the other of the sweet blue, almost azure, variety for which some spots in the neighbourhood of Tunbridge Wells are noted. All the variations I have named occur around that beautiful inland wateringplace, and do not appear to have any particular connection with different soils or situations; indeed many degrees of hue, from blue and reddish-purple to white, are found in company. The richest and purest pink flowers I found on the noble range of the lower greensand, near Sevenoaks.

Polygala vulgaris. The variation of this between perfect blue and perfect pink to a nearly perfect white is well known. I have never found a specimen wholly white, blue being in the so-called white

milkwort always more or less present, though sometimes not in a strongly-marked degree, upon the base of the corolla. The pure blue and pure pink are found in the tall, strong, many-blossomed hedgerow form, as well as in the short, spreading plant of hill-sides and heaths; but the white, so far as my experience has gone, in the latter form alone.

Oxalis acetosella is wholly white at times, though usually the delicate veins of the petals are exquisitely lilac in their colouring. But it also alters in the other direction, and is found in the lanes of Treflach, near Oswestry, of a rich and full pink. Anthyllis vulneraria has occurred on the Capstan Rock at Ilfracombe, of a pale cream-colour, tinged with blue. That being the first specimen of the plant I met with, it was with surprise I afterwards found how widely it differed from the ordinary yellow flower. Symphytum officinale, it may be noted, occurs abundantly around Oxford in two kinds-one of the usual red and purple, and the other with flowers entirely of a yellowish creamcolour. Oxford.

W....

when seen under the microscope. These, as well as the mature insect, are found on the underside of the leaves they prey on, which, having pierced, they extract the juice, depositing it in black spots over the leaf. This being of a glutinous nature, fills the pores, and afterwards the leaf turns pale yellow or a sickly green, and falls off. In March the full-grown insects are found collected together, and as the warm sun of spring comes forth, they depart abroad to raise a household for themselves. Another species, called T. ochraceus, feeds on fruit, and does

*

NOTES ON GREENHOUSE PARASITES.

VERY

VERY many there be, who are possessed of conservatories and greenhouses, who are perfectly unacquainted with the various kinds of injurious insects that dwell in them, more especially those which feed on the life-juices of the plants, on which, if they are left undisturbed, they will in due time cause their annihilation. Generally all is left to the gardener, who knows the various devices that are requisite for restoring to health the sickly plant. A professed gardener undoubtedly is a luxury; but alas, what does the poor amateur, who may have for the first time undertaken the care of a greenhouse, know about these aggravating insects? When he sees on his plants a curious and unknown object, he suspects it is injuring] them-at least he judges so from their unhealthy appearance. Having said this much by way of an introduction, I shall now proceed to give a brief description of these parasites. I shall not, however, allude to the Aphides, the most mischievous tribe of all, as in the columns of this journal have appeared from time to time various notes on them. The next greatest pest is the Thrips Adonidum (figs. 29 and 30), which in the summer season abounds on every out-of-door flower;

as,

for instance, the blossom of the Bindweed, Dandelion, Rose, &c. This insect is minute, its colour being generally black or rusty; the abdomen is long and pointed, and its wings are of a dirty white; the antennæ and legs are yellowish, the extremity of the former being black. The larva and pupa are of a pale yellow, and very unsightly to behold, especially

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one, but is more hairy. The next destroyer appears under the classical name of Coccus, or scale insect (figs. 31 and 32). Those generally found fixed on the stem and leaves of the plant are females. They are shield-like in shape, being convex above and flat or concave below; have six small legs; and as the insect increases in age, these grow into their bodies. On the underside of the insect is a sucker, with which it pierces the cuticle of the plant, so as to obtain the desired food. Soon after the female lays her eggs she dies, and her body becomes covered with a long white woolly substance, that guards her eggs during their incubation. The "Cocci" are of various colours, the darkest being

generally the fullest-grown: the males are active, and are very small. There are many species of the same insect, known as C. Vitis, C. Testudo, C. Hesperidum, &c. They should be exterminated as soon as they appear, for if let get ahead, there will be great difficulty in effecting this afterwards, as they increase at a prodigious rate. Another pest is the Mealy Bug" (fig. 28). This is not unlike the common Wood-louse, but is of a reddish colour,

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generality of the Acari tribe. It is found on the underside of the leaves of the plant infected; while there it sucks the juices out of them, and by the web it spins from vein to vein, destroys the power of healthy inhalation of the life-giving gas; the leaves then turn of a pale colour and fall off. This in many instances destroys the vitality of the plant. One thing is very remarkable,-how Nature has provided for the safety of these insects by giving them the instinct to hide from general view, on the underside of the leaves, telling them, as it were, "that they are thieves, and must work in the dark." There are many modes for destroying these enemies of vegetable life, the principal being fumigation, syringing, and painting the stems and leaves with compounds of a powerful nature. Deeming it would be unsuitable in this paper to give a recipe for each application, they in fact being "legion," I shall conclude by saying that these are to be found in most horticultural works, which are easily attainable for reference.

RALPH H. WESTROPP, B.A., T.C.D.

Altyflin Park.

DEFOLIATION, AND SIMILAR VEGETABLE PHENOMENA.

OF

all the theories which, intended to account for such phenomena as defoliation, defloration, &c., none of them to my mind can be regarded as satisfactory when viewed in the light of certain wellestablished facts connected with botanical teaching generally.

The conclusion I have arrived at, is one which being obviously justified on natural, physiological, and scientific grounds, I accept as the most probable and supportable theoretic explanation, as perhaps it is possible to give in accounting therefor.

In the first place we will, in order to comprehend the matter aright, take the conditions necessary to the formation of the green colouring principle of plants,-Chlorophyl. That this must have for its development light, is indisputable; also that it is dependent upon the sap as its distributing medium, is alike incontestable; and then connected with the sap, which I take to be analogous to what blood is in animals, there is another, and that an all-important point, to be recognized in considering the subject,it is Cold. Now from observation we all know, and that all the better because reminded of it every year, the effects that cold winds, frosts, &c., have upon leaves and other temporary organs of plants, such as the flower and fruit. Still in none of them do we notice it so much as in the leaves. For these, so soon as autumn commences, begin, as a rule, to wither and assume their autumnal tint, and eventually to defoliate. But in this, as in most other things, we have exceptions. Else, what of the ever

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