S

THE HOUSE SPIDER,

PIDERS are not now ranked among insects; because, as the handbooks of entomology state, "they have no antennæ, no division between the head and the thorax; they breathe by leaf-shaped gills situated under the belly instead of spiracles in the sides; have a heart connected with these; have eight legs instead of six, and six or eight fixed eyes. With the exception of the dragon-fly, whose head is terribly armed, there is not, perhaps, another creature possessed of such a fearful array of weapons as the spider. These weapons form beautiful microscopic objects, and as such they deserve attention.

The house spider (Aranea domestica) has eight simple eyes; these are set in two rows in the upper part of the head, and beneath them are the two larger jaws or mandibles; each of these mandibles contains a number of teeth, and is terminated by a large claw, a portion of the inner side of which is finely serrated. The number of teeth in a mandible is perhaps variable: there are eight in the specimens from which the figure given in this paper has been taken (fig. 2), but sometimes five only have been found. The claws frequently vary somewhat in the curvature of their ends, and are more finely pointed in some instances than in others.

I have read somewhere that the action of these claws is downward: this I have not been able to verify, for in the cases in which I have seen them in action, they were nearly horizontal, having only a slight inclination downward; and in the cast skins

Fig. 2. Mandible of Spider.

to be found on old walls, the claws lie close to the mandibles, and in a horizontal direction. Beneath the mandibles are the maxillæ (fig. 3), or smaller jaws, each of these contains a row of very fine teeth, and at the end of each row there is a thick tuft of hair. The teeth are so placed that in all probability the two rows work against each other, and each tuft

Fig. 3. Maxillæ of Spider.

With the assistance of an ordinary pocket magnifying glass the action of the mandibles may be distinctly seen. It is a curious thing to watch a spider making a repast of a fly; to see with what dexterity it uses each mandible alternately, as, with the greatest ease, it turns the body of the fly round, and presses it until it becomes a shapeless mass of juicy pulp.

The mandibles contain the poison, and the poison duct may be traced to the extremity of the claw, if the latter be sufficiently bleached before mounting.

The rapidity and fatality of the action of the poison has frequently been a subject of remark; the following simple observation sets it in a clear light. A stout fly became entangled in the web of a spider: quick as lightning, out darts the spider and seizes the fly, and equally quick was the interference to the rescue; it was relieved and set at liberty, the fly then walked smartly up a window-pane, stopped awhile, brushed its wings with its hind feet, rubbed its feet, and dressed itself; this was the action of a minute. It then walked about again, apparently all right. Presently it stood without motion, and after a few seconds, when touched, it was found to be scarcely able to raise its feet, and after a few seconds more it was quite dead.

Much interesting matter relative to insects may easily be obtained by the exercise of a little patient and continued observation. The above has been written with the desire of calling the attention of the general reader to a few of the wonderful things in the common objects of nature, and pointing out to the young microscopist two objects easily found upon which the first efforts at mounting may be successfully exercised.

LEWIS G. MILLS, LL.B., Armagh.

In a very rich piece of newly broken-up ground I gathered, a few years ago, some leaves of Dandelion (Fig. 4), which, owing to luxuriant growth, had become enormously large and much more deeply cut than usual, being, in fact, bi-runcinate. Leaves often become more deeply cut from poverty, and more simple through luxuriance, but in this case the extra cutting was undoubtedly caused by the richness of the soil, there being several similar plants, each of which was nearly two feet across.

In another case, however, of Horse-radish (Fig. 5), the radical leaves of nearly all the plants in my garden became last year so deeply cut as to be almost pinnate. This was no doubt caused by the dryness of the season. The horse-radish is a plant which loves a cool, moist soil, establishing itself by the side of water, and in the half-dry beds of rivers, where it grows luxuriantly, and the continued drought impoverished the plants. It is quite the character of the order Crucifere to have pinnatifid or lyrate leaves, and it is somewhat remarkable that

Fig. 7.

Figure 7 is a drawing of a not unfrequent form of Plantain (Plantago lanceolata), which has become proliferous, producing small flower-heads on footstalks and several leaves from the base of the flower. Gathered at Beaumaris during the last

summer.

Fig. 8 is a very interesting example of Marvel of Peru (Mirabilis jalapa), which has grown in my garden during the last summer. This plant belongs to the natural order Nyctaginaceae, a tribe in which there is no corolla, but the calyx becomes coloured, and is placed, solitary or clustered, in an involucre

Whilst at Llanberis during the past summer, I found, in the garden of the hotel where we were staying, a curious flower of Weigelia, very similar in its abnormal development to a primrose which I described

Fig. 8.

of leafy bracts. In the case of the Marvel of Peru, however, no one would suppose, from merely looking at the flower, but that there was a beautiful crimson or yellow or streaked monopetalous corolla placed within an ordinary green calyx of five sepals. Botanists tell us, however, that this corolla is no corolla at all, but a calyx, and that what we supposed to be calyx is only bracts. In the specimen figured, two of these coloured perianths have grown within one pseudo-calyx, showing that the latter organ is really an involucre, and establishing the relationship of this plant with Nyctago and other genera in which the nature of the involucral leaves cannot be mistaken. Such specimens have been observed before, and been made use of in proving the affinities of Mirabilis.

I have several times noticed a curious variety of the Common Columbine (Aquilegia vulgaris), which I think comes up the same year after year, but on this point I am not sure. The flower of this variety is entirely destitute of the horn-shaped hollow petals so characteristic of the plant, but their place is taken by a second and often third ring of flat leaves, which are either altered petals or multiplied sepals, and which give the flower very much the appearance of the double form of Love-in-a-mist (Nigella), minus the pectinated involucre. I made no drawing of this variety at the time, but the following outline from memory will serve to explain it sufficiently (Fig. 9).

in No. 5 of SCIENCE-GOSSIP. There was a corolla of the usual shape and size, which contained only one perfect stamen, all the other internal organs being converted into a short branch, upon the base of which were placed two or three leaflike greenish bracts, and on the summit a second corolla, rather irregular in shape and containing half-developed stamens and pistil.

The flowers of the double-blossomed Cherry, which are so great an ornament in our gardens in May, always show us some interesting examples of abnormal development. The duplication of the flower is effected by the conversion of some of the numerous stamens into petals, a considerable number of the stamens remaining still unchanged, so that if the pistils were perfect, there would be no reason why the double-blossomed cherry should not always produce

fruit.

If the flowers be examined, however, the pistil will be found to have suffered change, becoming, not a new series of petals, but two little green leaves, folded one within the other, in the centre of the flower. Now and then the pistil remains perfect, and if it happen to be fertilized by the stamens it grows, and we do find occasionally one or two ripe cherries on a tree. Last year I observed on a tree in my own garden, that in very many of the flowers the two little central green leaves had become a regular calyx enclosing a second double-flower.

The Poet's Narcissus (N. poeticus), which we in Cheshire call by the pretty name of "Sweet Nancy," is very curious in its manner of duplication. I have many patches of it, some of which are semi-double, being either double ones reverting to single, or single ones becoming double, I know not which; and in these the way in which the flower becomes double may be well seen. A single flower consists of six leaves united into a tube, around the mouth of which stands the crimson cup-shaped nectary, six stamens being attached to the sides of the tube.

If one of these semi-double flowers be examined, it will be found that each stamen has become, not merely a new petal, but actually a new flower, for it forms a tube, the mouth of which consists of, on one side a crimson nectary, on the other a white petal (fig. 10, a), and frequently, attached to this nectary, a bristle (fig. 10, 6), which I take to be a rudimentary stamen. These six new petals do not unite like the outer petals of the flower, but are always distinct from each other; and if the flower becomes quite double, it is by a multiplication of these inner florets, the change sometimes extending itself to the pistil, which separates into three unshapely petals.

In the autumn my children brought me half-adozen double damsons which were all found on one tree. The old order Rosacea is, now-a-days, broken up into several minor orders, one of which is Drupacea, which is distinguished from Rosacea proper mainly by there being only one ovary in the flower instead of several, this one ovary becoming eventually what we call a "stone fruit." If any plum tree be examined whilst in blossom, one can scarcely fail in finding a few flowers in which there are two, three, or more pistils and as many carpels, showing a tendency in the order Drupaces "to assume one of the distinguishing characters of Roseworts," as noticed by the late Dr. Lindley in his "Vegetable Kingdom" (Order Drupaceæ, p. 557). Generally, I think, these polygynous flowers drop off. Sometimes, no doubt, one carpel will come to maturity and the others will dwindle away, and we have only a one-celled fruit from several pistils, as is the rule in Cocoa-nuts, Hazel-nuts, and many other plants. But occasionally all the pistils become fertilized, and the result is a compound fruit as in the present instance.

More than one botanical friend has remarked to me upon the prevalence of monstrous forms of flowers during the past summer. As far as my own experience goes, I have not found them more plentiful than usual; indeed, I think that a wet season is generally more productive of abnormal growth than

a dry one, such as we have had. But I am rather inclined to think that 1 do see, last year, some little difference in the character of the abnormal forms; that, whereas, in ordinary seasons, the tendency in monstrous flowers is a reversion to leaves; this has not been so much the case during the dry, hot summer of 1865. ROBERT HOLLAND.

VEGETABLE FIBRES.

AT a recent meeting of the Quekett Microscopical

Club, a paper was read on the application of the microscope to the discrimination of vegetable fibres. The object of this communication was to point out what had been done, and to suggest what remained to be accomplished, and the best mode of performing it. Although adulterations of food have been well cared for and deeply investigated, adulterations or admixtures in fabrics, whether of animal or vegetable origin, have hitherto obtained but little attention. Yet, it is urged, the subject is an important one and well deserving systematic research. All fibres employed for commercial purposes may be divided into four classes, two of which are animal-i. e., wool and silk-and two vegetable; which may be termed vascular and cellular.

WOOL has a peculiar structure, readily to be distinguished from all other animal and vegetable fibres (fig. 11, 6), and differing slightly in its own varieties,

Fig. 11. a. Cotton; b. Wool; c. Silk.

as may be seen by reference to a paper on hairs in our first volume. (Vol. i. p. 29.) Yet we have no work of authority, and no reliable figures of the microscopic appearances of different qualities and classes of wool, even of those ordinarily met with in commerce. It must be possible to characterize microscopic features whereby Saxony can be distinguished from South-down, and Australian from East Indian.

SILK (fig. 11, c) is more uniform in its character,

and the difficulty would be greater to point out the features which distinguish the produce of the mulberry worm from that of the Tusseh of India, the Moonga or Erie of Assam, and the Ailante of recent introduction into Europe.

Vegetable fibres of the cellular kind are hairs which invest the seeds of certain plants, COTTON being of the chief importance (fig. 11, a). This has been described as a flat band with thickened margins, and a delicate tracery down the centre; much twisted throughout its length. This may appear to be the structure on a superficial examination of the dried cotton, but the normal structure is certainly that of a cylindrical hair with thin walls, readily collapsing and twisting as it becomes dry, its apparent margin being formed by incomplete compression and the resistance at the edges as seen in the following section of a fresh( fig. 12, a) and dried hair (b). The supposed tracery is an optical illusion,

country or climate of production. It is natural to inquire whether the microscope can detect differences between Irish and Belgian, or between Egyptian and Spanish flax. In 1860, Dr. Forbes Watson communicated an important paper to the Society of Arts, in which the microscopic character of vegetable fibres received more attention than had ever before been given to the subject, and since that period nothing has been attempted in advance. The woodcuts used to illustrate these observations were prepared for that occasion, and have been kindly placed at our disposal by Dr. Watson. The microscopic characters we are about to give are those which then accompanied the illustrations.

The flax fibre (fig. 13, a) presents at varying distances certain characteristic cross markings, the outlines of the fibres are hard and smooth, and the ultimate fibrillæ can seldom be detected until carcfully detached from the ordinary fibres.

A strong fibre is obtained from the Chinese nettle, or RHEA (see S. Gos., vol. i. p. 277), known botanically as Boehmeria nivea, and sometimes called China-grass. Under the microscope its fibres present a peculiarly rough appearance, and when viewed by reflected light have an appearance not unlike frosted grass.

Another Indian nettle, called the NEILGHERRY NETTLE (Urtica heterophylla), of which a figure has already been given (vol. i. p. 276), yields a similar but more woolly fibre. (Fig. 14, b.) Under the

The most important of liber-fibres is FLAX, obtained from the common flax plant (Linum usitatissimum). This possesses a variable market value according to

Fig. 14. a. Chinese nettle; b. Neilgherry nettle; c. Bedolee. microscope it exhibits considerably greater asperities than the Rhea, and has been recommended as a substitute or for admixture with wool. A comparison of the two figures (fig. 11, 6, and fig. 14, 6) will prove that such an admixture could readily be detected.

The fibre of the MUDAR (Calotropis procera) is similar in commercial value, but characteristically