absorbed. In this situation there is a vacant space partly occupied by the caruncle, called the lacus lachrymalis (fig. 11, d); it is a sort of reservoir or rather sink for the tears. Above and below, at the entrance to this space where the ciliary margins terminate, there is a small prominence on the inner edge of both (figs. 11, a; 14, a), centrally punctured by small orifices. These are the puncta lachrymalia. Their inward aspect is well shown in fig. 13. They are the emunctories of the eye; and their function is to absorb the fluids presented to them, and convey them by two converging canals (fig. 14, a) to the lachrymal sac (fig. 14, c), which they enter by a common orifice (fig. 14, b). This is a membranous bag about as large as a kidneybean lodged in a groove in the lachrymal bone, behind the tendon of the orbicular muscle. The lachrymal sac entering a vertical channel in the bone at the end of the groove is narrowed into the lachrymal canal (fig. 14, d), and passes directly downwards into the inferior meatus or chamber of the nose, which it enters on the outer side by a slit in the mucous lining. It is not exactly understood in what way the puncta absorb-whether by capillary attraction or by some vital force of suction. The side of the lachrymal sac is connected with the tendon of the orbicularis, which may aid in producing the effect by suddenly drawing its membranous surfaces apart. We all know the effect of repeated winking when the eyes are filled with tears. Nervous and Vascular Constitution of the Eye.-Enough has been already said, for general information, with respect to the bloodvessels distributed to the eyeball, and it is not necessary to mention those which supply the appendages. With respect therefore to vascular arrangements we have only to add, that although there are abundant proofs of the existence of an active absorption within the globe, no lymphatic vessels especially destined to that function have been hitherto found in it. The optic or second cerebral nerve has been already described. All the straight muscles, with the exception of the rectus externus, the inferior oblique, and the levator palpebræ, are supplied by the third nerve. The fourth is wholly distributed to the trochlearis, and the sixth to the rectus externus. The orbicular muscle is supplied, like most of those of the face, by the portio dura of the seventh pair. All these, except the optic, are muscular or motor nerves. The fifth nerve supplies the whole organ in common with many other parts with ordinary sensation. Any account of the intricate nervous constitution of the iris would be here quite out of place. The third and sixth nerves are mainly concerned in it. Thus of the ten cerebral nerves, the second, third, fourth, and sixth are wholly, and the fifth and seventh partially distributed to the organ of vision; a fact which may give some idea of the elaborate organisation and varied exigencies of the parts which compose it. Comparative Anatomy of the Eye.-The sense of sight is undoubtedly developed amongst the lowest class of animals, but it is difficult to point out the exact members of the series in which this faculty is first exercised. The moving zoospores of plants are attracted towards the light, and Ehrenberg regards as eyes the red spots seen in some organisms, such as Volvox, which are now regarded as plants. All anatomists are agreed on regarding the ocelliform spots situated at regular intervals along the margin of the disc of Pulmograde Medusa as eyes. They are composed of a collection of pigmentary granules, superposed upon an enlargement of a nervous thread, which comes from the central circle of nervous matter in the animals. Similar spots have been observed at the extremities of the rays in the Asteriada by Professor E. Forbes. In many of the lower Articulata no higher development obtains. In the Entozoa no visual organ has been detected. Distinct eye-spots are seen in the Leeches, the Rotifera, and the Dorsibranchiate Annelida. Amongst the mass of Mollusca these organs are not observed. They are however very distinct in the Pectens and other swimming forms of Lamellibranchiate Mollusks.

"The eyes of most of the higher articulated animals are constructed upon the composite type, each of the masses that is situated upon either side of the head, being made up of an aggregation of simple eyes, every one of which is in itself a complete visual instrument, but is adapted to receive and to bring to a focus only those rays which come to it in one particular direction. In most insects each composite eye forms a large hemispherical protuberance, which occupies a considerable part of the side of the head, and when examined with a microscope, its surface is seen to be directed into a vast number of facets, which are usually hexagonal. The number of these facets, every one of which is the cornea of a distinct eye, is usually very great. Behind the cornea is a layer of dark pigment, which takes the place and serves the purpose of the iris in the eyes of the Vertebrata, and this is perforated by a central aperture or pupil, through which the rays of light which have traversed the cornea gain access to the interior of the eye. When a vertical section is made of one of these composite eyes, it is seen that each separate eye is the frustum of a pyramid, of which the cornea forms the large end or base, whilst the small end abuts upon a bulbous expansion of the optic nerve. The interior of this pyramid is occupied by a transparent substance which represents the vitreous humour, and the pyramids are separated from each other by a layer of dark pigment which completely incloses them, save at the pupillary apertures and also at a corresponding set of apertures at their smaller ends, where the pigment is perforated by the fibres

of the optic nerve, of which one proceeds to each separate eye. Each facet of the common cornea or corneule' is usually convex on both its surfaces, and thus acts as a lens, the focus of which has been ascertained by experiment to be equivalent to the length of the transparent pyramid behind it; so that the image produced by the lens will fall upon the extremity of the filament of the optic nerve which passes to its truncated end. The rays which have passed through the several corneules are prevented from mixing with each other by means of the layer of black pigment which surrounds each cone; and thus no rays, except those which correspond with the axis of the cone, can reach the fibres of the optic nerve. Hence it is evident that each separate eye must have an extremely limited range of vision, being adapted to receive but a very small pencil of rays proceeding from a single point in any object; and as these eyes are usually immoveable, they would afford but very imperfect information of the position of surrounding objects, were it not for their enormous multiplication, by which a separate eye is provided (so to speak) for each point to be viewed. No two of the separate eyes, save those upon the opposite sides of the head which are directed exactly forwards, can form an image of the same point at the same time, but the combined action of all of them may give to the insect, it may be imagined, as distinct a picture as that which we obtain by a very different organisation. At any rate it seems certain, from observation of the movement of insects, that the vision by which they are guided must be very perfect and acute.

"Although the foregoing may be considered the typical structure of the eyes of insects, yet there are various slight departures from it in the different subdivisions of the class. Thus in some cases the posterior surface of each corneule is concave, and a space is left between it and the iris which seems to be occupied by a watery fluid or aqueous humour; in some instances again this space is occupied by a double convex body which seems to represent the crystalline lens; and there are cases in which this crystalline lens is found behind the iris, the number of eyes being reduced, and each individual eye being larger, so that the entire aggregate approaches, both in its structure and mode of action, to that of Arachnida and certain Crustacea. Besides their composite eyes, insects usually possess a small number of rudimentary single eyes resembling those of the Arachnida: these are seated upon the top of the head, and are called stemmata. Their precise use is unknown, but that they have considerable influence in the direction of the movements appears from the fact that, if the stemmata of a bee be covered with paint, on being let go it will fly continually upwards a fact which seems related to those already mentioned in regard to the influence of visual sensations upon automatic movements. It is remarkable that the larvæ of insects which undergo a complete metamorphosis only possess simple eyes, the composite eyes being developed at the same time with the wings and other parts which are characteristic of the imago state during the latter part of the pupa condition. In the higher Crustacea the structure of the eyes is nearly the same as in insects; but the compound masses are not so large relatively to the bulk of the body, and the number of distinct eyes is not nearly so great. In the lower Crustacea however, as in Myriapoda, the visual organs much more closely approximate the type of structure which they present in the Arachnida; each aggregate mass being composed of a small number of simple eyes, of which every one has its own separate cornea as well as its own crystalline lens and vitreous humour, and these in some instances being altogether detached from each other. Among some of the Suctorial Crustacea the visual organs are altogether wanting in their state of full development, although they are uniformly present in their early condition; and the same may be said of the Cirrhipedia. Among Arachnida, which in this as in many other respects present an approximation to Vertebrata, we find a great reduction in the number of eyes, which are never more than eight in number (sometimes being only two), and are to be compared with the stemmata of insects rather than with their compound eyes. These eyes are sometimes collected into one mass on the summit of the cephalo-thorax, and are sometimes symmetrically and separately on the two sides of the median line. In the Scorpions we find two large eyes placed on the dorsal aspect of the cephalo-thorax near the median line, and three pairs of smaller ones, which are placed on the outer margins of the same division of the body. The larger eyes are described by Müller as each possessing a cornea which is convex anteriorly and concave posteriorly; and a nearly globular crystalline lens resembling that of fishes, whose anterior surface lies in the hollow of the cornea, while its posterior rests upon the vitreous humour, without being imbedded in it. The vitreous humour is a nearly hemispherical mass of soft granular matter, being almost flat in front and very convex behind; over its posterior surface is spread the retina, or expansion of the optic nerve; and this is covered by a thick layer of pigment which passes inwards in front of the vitreous humour so as to form a sort of iris, the pupillary aperture of which however exceeds the diameter of the crystalline lens. Among those classes which constitute the higher division of the Molluscous series in virtue of the possession of a distinct head, the presence of visual organs is by no means constant; many Gasteropoda and Pteropoda being destitute of them altogether, and others possessing ocelliform spots, which may be concluded to be rudimentary eyes from their

similarity in position to the eyes of those which undoubtedly possess visual powers. The eyes are always very minute however in proportion to the bulk of the body, and in no instance do they possess a high type of structure; their general organisation indeed bears a close resemblance to that which has been described in the eye of the Scorpion. In the Cephalopoda we find the visual organs presenting a much larger size, and attaining a much higher grade of development, in accordance with their greater functional activity in directing the rapid and energetic movements practised by a large proportion of these animals. We here find nearly all the principal parts which are characteristic of the eye of higher animals, namely, a cornea, an anterior chamber filled with an aqueous fluid inclosed in a distinct capsule, a crystalline lens of globular form (as in fishes), a large posterior chamber filled with vitreous humour, a tough fibrous or sclerotic coat, a vascular choroid coat within this covered by black pigment upon, its inner surface and retinal expansion. The relations of this last to the optic ganglion however are very peculiar. This ganglion is situated almost close to the back of the eye, and instead of transmitting a single optic nerve as in higher animals, it gives off a multitude of filaments which separately pierce the sclerotic coat, and then form a plexus between this and the choroid, which has been mistaken for the retina. The true retina however is very thin lamella apparently composed of vesicular nerve-substance, which is found between the pigment and the membrane inclosing the vitreous humour; but the connection of this with the net-work of nerve-tubes on the outside of the pigmentary layer has not yet been made out. No proper iris exists in the eyes of the Cephalopoda, but its place is supplied by a partial prolongation of the sclerotic coat over the front of the crystalline, a central pupillary aperture being left. The cornea is not, like the true cornea of higher animals, a transparent continuation of the sclerotic coat, but is a modification of the general integument, analogous rather to the external or conjunctival layer of the cornea of Vertebrata: it is remarkable that in some Cephalopoda it should be perforated by an orifice of considerable size, through which the capsule of the crystalline lens projects into the external medium." (Carpenter, 'Principles of Physiology.')

The eyeballs of quadrupeds and other Mammalia resemble the human organ in structure, and differ from it, but not essentially, in form. This is not the case with the appendages. One of the most remarkable additions commonly found to the parts we have described is that of a strong retractor muscle in the shape of a hollow cone attached at the apex to the bottom of the orbit, and by the marginal base to the sclerotic, which it embraces, lying under the recti muscles. Its use is to draw back the eye in the orbit, a gesture which gives a very peculiar expression of hollowness to the organ in beasts of prey. We subjoin the following account of the eye of the Common Owl (Strix bubo), chiefly for the purpose of explaining the pecten and the curious mechanism of the third eyelid, or nictitating membrane, in birds.

The general shape of the organ represented in the annexed figures resembles a bell. This arises from the disposition of a series of quadrangular bony scales (fig. 15, a) within the substance of the sclerotic, concave on their outer aspect, and overlapping and accurately fitted to each other. The rigidity thus communicated to the external case which contains the fluid media prevents their pressure from distending the eye into a spherical shape. The ciliary body (fig. 15, b) extends over the whole of this portion of the surface. A curious membrane called the pecten or comb (fig. 15, c), from some resemblance to that implement, projects through the choroid into the vitreous humour, and in some birds is attached to the side of the lens. In the owl it is comparatively short. It resembles a quadrangular piece of choroid folded backwards and forwards upon itself like the paper of a lady's fan. Of its use little is known. The foramen of Soemmering, described in the account of the human retina, is thought to be a rudiment of the pecten. In birds the retina has generally the yellow colour seen only partially in man round the central spot miscalled a foramen.

Fig. 15.

Horizontal section of the eye of the Common Owl (Strix bubo).

a a, bony plates in the sclerotic; b, ciliary body; c, pecten. At the back of the globe there are two muscles which originate from the sclerotic, and are applied to its curved surface round the

Fig. 16.

Head of the same bird.

muscles.

A portion of the bony margin of the orbit having been removed, the eyeball is turned forward so as to show the recti and other entrance of the optic nerve. (Fig. 17, a.) The larger represents rather more than half of what if completed would be a broad circular ring. (Fig. 17, b.) It is called the quadratus. Attached by its wider edge near the margin of this part of the sclerotic, its fibres converge to the narrower edge, and terminate in a narrow tendon (fig. 17, c), perforated through its whole length like the hem of an apron. The second smaller muscle, called the pyramidalis from its shape (fig. 17, d), at an opposite part of the circumference. Its fibres converge, and are fixed into a long round tendon (figs. 17 and 18, e), which passes through the loop or hem (c) of the quadratus, and hence turning over the edge of the broad part of the sclerotic, is continued along the surface of its bell-shaped portion, where it passes through several thread-like loops or pulleys which keep it applied to the concavity, and round a bony point which projects from the surface, and is Fig. 17. Fig. 18.

4

Fig. 18. Lateral view of the same part. e, the tendon of the pyramidalis, attached to the concave part of the sclerotic by tendinous loops, and passing round a prominent bony tubercle, is seen inserted into the nictitating membrane at f. attached near the edge of the cornea to the edge of an elastic fold (fig. 18, f) of the conjunctiva, which is called the third eyelid or nictitating (that is, winking) membrane. It will be easily seen by the help of the figures, from this description, that the effect of the simultaneous contraction of the two muscles will be to draw the membrane with great rapidity, making it sweep over the surface of the cornea. It returns by its own elasticity with nearly equal quickness. A bird may be seen to use this mechanism twenty times in a minute; in fact, as often as it may be necessary to cleanse the surface of the eye. The colour of the membrane is milky; and it is seen to pass from the upper and inner to the outer and lower corner of the eye with the speed for which the act of winking is proverbial. There is a rudiment of this third eyelid in the human organ. It is a small crescentic fold of conjunctiva situated at the inner canthus behind the caruncle. (Fig. 13, f.) The haw is also a rudiment of it, in the eyes of quadrupeds; it is occasionally forced out by the pressure of the globe against the nasal side of the orbit, being unprovided with muscles.

Seat of Vision.-The retina in one sense is not the seat of vision. It is necessary to the perception that the impression of light should be received on another part not endowed with sensibility, namely the surface of the choroid; and that the vibration or other effect thus impressed should be transferred to the retina in front of that surface; for where the choroid is deficient at the entrance of the nerve, there is no perception of light. This may be easily shown by a very common and conclusive experiment. If two discs of white paper be fixed upon a wall at the distance of two feet from each other, and an observer, having closed one eye (the left), continues to gaze attentively at the left-hand disc, at the same time slowly retreating from the wall, he will for a time continue to see them both; the rays from the right-hand object entering of course laterally, and impinging upon

the retina nearer and nearer to the entrance of the nerve as he goes backward. At length when he has reached the distance of about 6 feet from the wall, the right-hand object will suddenly disappear, and remain invisible (the observer still retreating) till he has gained a distance of about eight feet. During this period the spectrum has been passing over the circular aperture in the choroid through which the nerve enters. The insensible portion of the retina is found to extend horizontally over five degrees and a half of the angular range of vision. The eyes are generally unequal in power, and the experiment succeeds best in the weaker organ, in which the obscuration is more sudden and complete. In the experiment previously mentioned, showing the distribution of the central artery of the retina, the surface of the choroid is faintly illuminated through the transparent nervous expansion by what is called the dispersion of part of the light admitted through the pupil; but the rays thus scattered are locally intercepted by the opaque blood contained in the minute branches of the artery; hence, after several repetitions, when the eye has become accustomed to neglect the taper, and attend to the fainter internal illumination, the shadow of the vascular net-work upon the choroid becomes perceptible in dark lines. Apparent Direction of Objects seen obliquely.-A body in motion, as a ball, striking the surface of another, impresses it in a line perpendicular to the surface at the point of impact. This rule appears to hold good with respect to the action of light upon the retina. Indeed if impressions of any kind be made upon it, the sensation is that of light, and the direction suggested is that of a line joining the centre of the sphere of which the retina forms a part with the point impressed, in other words, a line perpendicular to it. This may be shown in several ways: if we excite the nerve by pressing far back upon the eyeball with the finger-nail, especially if the eye be closed or light otherwise excluded, a bright ring appears to be seen in a diametrically opposite quarter.

Erect Vision. If the sclerotic and choroid be carefully removed under water from the back of an eye, an inverted picture of any object held before the cornea is seen upon the now milky surface of the retina. Hence the celebrated question raised in the age of philosophical barbarism, how is it that we see objects erect when the image on the retina is inverted? The question is an idle one, which is perhaps hardly worth answering. The mind judges of the apparent place of objects or of parts of an object by the direction of the impressions made upon the retina, not by the part of it which may happen to be affected by these impressions. The shadow of the central artery is an example of an impression necessarily received always upon the same parts; yet the apparent, or in other words the relative, place of the shadow will be found to vary with every movement of the eye.

Single Vision.-Another question, not so trivial as the last, has been raised with respect to single vision with two eyes, as the impression must be twofold. But perhaps it will not require an answer if the reader will try to imagine double vision of the same object, or rather of the same point, for the question resolves itself into that. Let the two supposed images approach each other, still remaining double, till they are in contact. Another step in the imaginary approximation, and they are one. The truth is, that both eyes see the object in the same place; and as two images, no more than two material substances, can occupy the same place at the same time, the impressions coincide and are single.

On the Development of the Organ of Vision.-The following remarks on this subject are from Professor Kölliker's 'Manual of Human Histology:'

"The eyeball is not developed from a single point as a whole, but arises from the conjunction of formations, proceeding on one side from the central nervous system, on another from the skin, and thirdly from the parts lying between the two.

nerve.

An interesting phenomenon is presented in the vessels existing in the fatal eye, even in the transparent media. The vitreous body on its outer surface, between the hyaloid membrane and the retina, presents a tolerably wide meshed vascular plexus, which is supplied by branches of the arteria centralis retina, given off from it at its entrance into the eye, and anteriorly, at the border of the lens on the zonula Zinnii forms a vascular circle, the circulus arteriosus Mascagnii, from which again vessels are given off to the membrana capsulo-pupillaris presently to be described. Besides this, a special arteria hyaloidea, also derived from the central artery of the retina, runs in the so-called canalis hyaloideus, in a straight line through the vitreous body to the lens, and ramifies in the most elegant arborescent manner at very acute angles in a membrane closely applied to the posterior wall of the lenticular capsule. This is nothing else than a portion of an externally vascular capsule which at first very closely surrounds the lens, and in its anterior walls is supplied by the continuation of the hyaloid artery coming round the border of the lens towards the front, with which branches of the circulus arteriosus Mascagnii and of the anterior border of the uvea are connected. Afterwards, when the lens retreats from the cornea, with which it is at first in close apposition, and the iris buds out from the border of the uvea, the anterior wall of the vascular lenticular capsule is divided into two portions, one central and anterior, which, arising from the border of the iris, and connected with that membrane by vessels, closes the pupil, the membrana pupillaris; and another external and posterior, extending backwards from the same points on the border of the lens, the membrana capsulo-pupillaris. The latter becomes more and more distinct as the iris and aqueous chambers are developed, and the lens retreats until at last it represents a delicate membrane stretching across the posterior chamber.

"The venous blood from all these parts is returned through the veins of the iris and from the outer surface of the vitreous body, also through those of the retina, and perhaps through a vena-hyaloidea said to take the same course as the artery, but of the existence of which many authors doubt, and which I have never myself seen. With respect to the genetic import of the vascular capsule, nothing has as yet been ascertained. I find it to be composed of a homoge neous tissue, with a few scattered cells, and regard it as a structure corresponding to the cutis which in the formation of the lens is detached from the skin, together with a portion of the epidermis, and remains in the eye. The vitreous body then may be understood as modified subcutaneous connective tissue-a supposition not at all incongruous with the observations above adduced, and the more 80 because, as I have shown, all the subcutaneous connective tissue of the foetus is at one time perfectly gelatinous, and, like the enamel organ, which also belongs to the same tissue, in specie strikingly resembles the vitreous body in aspect and consistence.

"Concerning the histological development of the eyes, the following only need be remarked. At an early period they consist in all their parts of formative cells of uniform size, which in process of time are metamorphosed into the various tissues. In the fibrous coat in the second and third month the cells are developed in the mode already described into connective tissue, and at the same time the distinction is set up between the cornea and sclerotic, which are at first externally exactly alike, and constitute only a single membrane. In the uvea the cells are for the most part employed in the formation of vessels; another portion goes to the formation of the inner and outer pigment layers, pigment granules being deposited in them at the com. mencement of the third month, whilst another is transformed into muscles, nerves, the epithelia and connective tissue of these membranes. The development of the nerve-cells and of the so-termed 'granules' from embryonic cells, may be readily traced. I have observed the same thing also with respect to the 'cones,' and I think that in the Frog it may be assumed with respect to the 'rods' likemalia the formation of the rods and of the nerve-fibres themselves, has not yet been traced. The lens, lastly, is originally composed entirely of cells, which in course of time are transformed into the tubes. "The precise nature of the processes attending these changes has not yet been investigated, although I agree with H. Meyer in the conclusion, that, since the tubes, both in the foetus and child, present only a single nucleus, each of them is developed out of a single cell. These nuclei, taken as a whole, constitute a thin layer extending from the borders of the lens, through the middle of its anterior half, and slightly convex in front (nuclear zone,' Meyer); the nuclei being smaller in the interior portions, and, as it were, in progress of solu tion, whence it may certainly be concluded that the lens increases by the apposition of thin layers from without. The formative-cells of the tubes of the lens are those which exist on the anterior half of the capsule, and the starting-point of the formation of the lenticular elements, according to my observation, is the entire anterior surface and the border of the organ. Nuclei are visible in the tubes even in the lens of the adult, as was known to Harting, though only at its margin."

(Kölliker, Manual of Human Histology, translated by Busk and Huxley for Sydenham Society; Valentin, Text-Book of Human Phy siology; Todd and Bowman, Physiological Anatomy; Carpenter, Principles of Physiology; Jones, Actonian Prize Essay on the Eye.) EYEBRIGHT. [EUPHRASIA.]

FABA, a genus of Plants belonging to the natural order Leguminosa. It has a tubular 5-cleft or 5-toothed calyx, with the two superior teeth shortest. The style is villous at the apex. The legume is large and coriaceous, lined with short hairs, and containing several large flat seeds. The leaves are almost without tendrils, and the stem is erect. The flowers are white or red.

F. vulgaris, the Common Bean, has thick leaves with 2-5 broad oval mucronate leaflets. It has semi-sagittate oval stipules, and the teeth of the calyx are almost linear.

turners on account of their hardness. At the Great Exhibition of 1851 a chair was exhibited composed entirely of these knobs. The leaves are shining and thin, changing to a brown or russet colour in the autumn, and often remaining on the tree throughout the winter. Its branches are numerous, and its foliage so dense that other plants do not thrive under it; so that there is seldom any vegetation seen on the ground in a beech forest. The Monotropa Hypopithys, Bird'sNest Orchis as it is called, is often found parasitical upon its roots. The fruits contain a nut or seed, which when ripe frequently drops out, leaving the husk upon the tree. The seeds are not disagreeable to the taste. Squirrels are fond of them, and are often found seeking them on these trees. The beech-trees in the forests of Germany generally attain the age of about 200 years. There is one in Windsor Forest which is supposed to have been in existence before the Norman Conquest.

MINOSE.

FABÓI'DEA, Mr. Bowerbank's generic title for Seed-Vessels found in the London Clay of Sheppey. (Fossil Fruits of the London Clay.') FECULA. [STARCH.]

FAGOPYRUM, a genus of Plants belonging to the natural order Polygonacea. It has a 5-parted perianth, 8 stamens, 3 styles, a 1-seeded trigonous nut, a central embryo, and large foliaceous contorto-plicate cotyledons. There is but one British species of this plant, the F. esculentum. This is the Polygonum Fagopyrum of Smith, and known as the common Buck-Wheat. It has an erect stem without prickles, the flowers in cymose panicles, 8 stamens, leaves cordate, sagittate, acute, a triquetrous acute nut, with entire angles. This is a valuable plant, as it grows on the worst and poorest soils, and is often sown as food for game. Though now admitted into the British Flora, there can be no doubt that it was originally a native of Persia and other Asiatic countries. It was introduced into Europe by the Crusaders; and hence in many parts of France, where it is commonly grown, is called Saracen Corn; and so much is it esteemed in Belgium, that M. Bory St.-Vincent says he was shown the tomb of the person who is reported to have first brought it into that country. [BUCKWHEAT, in ARTS AND SC. DIV.]

(Babington, Manual of British Botany; Burnett, Outlines of Botany.)

FAGUS (from payw, to eat), a genus of Plants belonging to the natural order Corylacea. This order is characterised by its male flowers being arranged in catkins, and the female flowers being solitary or on spikes, and the fruit surrounded by a coriaceous involucre. The genus Fagus has its stamens in a globose catkin; the perianth 5-6-fid; the stamens 8 to 15 in number; the pistilliferous flowers are 2 together, and contained within a 4-leaved prickly involucre; the stigmas 3; the ovaries 3-cornered and 3-celled; the fruit is a nut, which by the suppression of the ovules and cells is only 1- or 2-seeded. The species are large handsome deciduous trees, natives of Europe, North and South America, and Australia. The best known species is the Common Beech, which is a native of Great Britain.

F. sylvatica, the Wood-Beech or Common Beech. It has ovate glabrous obsoletely-dentate leaves, ciliated on their margins. It is a tree varying from 60 to 100 feet in height. It is a native of various parts of Europe besides Great Britain, and a variety is found in North America. Loudon, in his 'Arboretum et Fruticetum Britannicum,' gives the following varieties :

F. 8. purpurea, the Purple-Beech, which has the buds and young shoots of a rose-colour.

F. s. cuprea, the Copper-Coloured Beech, in which the young shoots and leaves are of a paler colour than in the last.

F. s. foliis variegatis, the Variegated Beech, in which the leaves are white and red, interspersed with streaks of red and purple.

F. s. heterophylla, the Cut-Leaved Beech, in which the leaves are separated in various ways.

F. s. cristata, the Curled-Leaved Beech. The leaves are curled up in this variety.

P. s. pendula, the Weeping Beech, in which the branches are pendulous.

P. 8. Americana, the White Beech. This is the American form of the Common Beech.

The Beech is remarkable for its smooth thin bark, which becomes white when fully exposed to the air. In the midst of it those knobs called embryo-buds, or abortive branches, are more often found than in any other tree. They are sometimes used by cabinet-makers and

NAT. HIST. DIV. VOL. II.

As fuel the wood of the Beech is superior to that of most other trees. It is consumed for this purpose to a great extent in France and Germany. It burns rather rapidly, but throws out a great deal of heat, and makes a clear bright flame.

The fruit, the nut of which is called Beech-Mast in England, and la Faine in France, has a taste somewhat approaching to that of the hazel-nut. It forms an excellent food for swine, but the flesh of those which are fattened upon it does not keep so well as that of those fed on acorns. Beech-mast is sought after by wild animals, such as badgers, dormice, &c. Beech-oil, expressed from the nuts, is used in cooking, also for burning in lamps. For useful plantations the Beech is not highly prized; it is chiefly valuable as an ornamental tree for the park and the lawn. It is subject to the attacks of comparatively few insects; those which do infest it belong chiefly to the Lepidoptera, and are in the caterpillar state. The fungi which grow on the Beech in Great Britain are rather numerous various species of Agaricus, Boletus, Polyporus, Peziza, Stromatosphæria, and Stilbum are mentioned. The most remarkable fungi growing beneath the Beech-Tree are-Geoglossum viride, Helvella esculenta, and Morchella esculenta, the common Morel. The last two species are celebrated luxuries for the table. Morchella esculenta grows in great abundance in the woods of Germany and France, particularly after any of the trees have been burned down. This having been observed, led in Germany to the practice of burning the trees in order to produce Morels, and conse quently great numbers of them were destroyed till it was forbidden by law.

F. ferruginea, the American Ferruginous-Wooded Beech, is a North American timber-tree, so much resembling the common European Beech as to be considered by some to be only a variety of it. It has ovate acuminate thickly-toothed leaves, downy beneath, ciliate on the margin. The American Beech is easily known from the European one by its much shorter obtusely-pointed buds, with short roundish convex scales, which terminate almost abruptly, and are inclosed in numerous short loose scales. There are two varieties of this species-F. Caroliniana and F. latifolia.

F. obliqua, the Oblique-Leaved Beech, is a native of Chili. It has ovate-oblong oblique leaves, somewhat rhomboid, blunt, doubly serrated, entire at the base, attenuated into the petiole, somewhat downy.

F. betuloides, the Birchlike or Evergreen Beech, grows at Port Famine, Straits of Magalhaens, in the greatest abundance. It attains a very large size, trees of three feet in diameter being common, and there being many with trunks four feet in diameter. This Beech is also a native of Van Diemen's Land, where it is called the Myrtle Tree by the colonists. It has ovate-elliptic leaves, obtuse, crenulate, leathery, shining, glabrous, round at the base, on short footstalks. The branches are divaricate, tortuous, brownish, the young ones pubescent, the leaves ciliate, alternate, from 4 to 10 lines long, and from 3 to 8 lines broad. The flowers are axillary. It is an evergreen tree, and forms vast forests in Tierra del Fuego, where it is a native.

F. antarctica, the Antarctic Beech, is a native of Tierra del Fuego. F. Dombeyii, Dombey's or the Myrtle-Leaved Beech, is a tall tree, a native of Chili, where it is known by the name of Coigué, and furnishes excellent wood for the purposes of construction.

F. dubia, the Dubious Beech, is thought only to be a variety of F. betuloides. By some botanists, however, it is considered a distinct species, and is described as such.

FAHLORE, Fahlerz, Gray Copper Ore. Of this there are two varie ties, the arsenical and the antimonial: the former occurs crystallised

2 Y

Silver, and a trace of Manganese.
Zinc
Loss

22.00

37.75

3.25

28.00

25

5:00

3.75

-100

Colour

FAHLUNITE, Tricklasite, a Mineral consisting of silicate of alumina and other substances. It occurs crystallised and massive. The primary form of the crystal is a right rhomboid prism, but it usually occurs in imbedded, regular, hexagonal prisms. yellowish, greenish, and blackish-brown. Nearly or quite opaque. Lustre resinous. Specific gravity 2.66. Hardness 5.0 to 5.5. Streak grayish-white. Cleavage perpendicular to the axis of the prism. It is found at Fahlun in Sweden.

Before the blow-pipe alone it becomes gray, aud fuses on its thinnest edges; with borax it melts slowly into a coloured glass. According to Hisinger it consists of

FALCON. [FALCONIDE.]

Foot of the Peregrine Falcon (Falco peregrinus).

The power of flight, as Mr. Yarrell observes in his memoir 'On the Anatomy of Birds of Prey' ('Zool. Journ.,' vol. iii.), is one of the decided marks of the distinct organisation of birds; and, as one division of the first genus, Falco, appears to possess this power in the highest degree of perfection, he proceeds to consider the conditions necessary to produce such a degree. These, he observes, are large and powerful pectoral muscles; great extent of surface, as well as peculiarity of form in the wing; and feathers of firm texture, strong in the shaft, with the filaments of the plume arranged and connected to resist pressure from below. "A certain degree of specific gravity," continues Mr. Yarrell, "is necessarily imparted by large pectoral muscles, and the power of these muscles may be estimated by the breadth of the sternum and the depth of its keel, as affording extent of surface for the attachment of the large muscle by which the wing is depressed. As an illustration of this form the breast-bone of the Peregrine Falcon (Falco peregrinus) is represented, which exhibits the

FALCONIDE, Leach's name for a family of Raptorial Birds, or birds of prey (Raptores of Illiger). In this family the destructive power is considered by all zoologists to be most perfectly developed ; and we find in the birds composing it natural instruments for striking, trussing, and dissecting their prey, combined with a power of flight and strength of limbs equivalent to the necessities of the case, whether the prey be aerial, that is, whether it be the habit of the raptorial bird in question to strike down its quarry while the latter is in the act of flight, or whether the prey be terrestrial, or, in other words, captured on the ground. Of these natural weapons some idea may be formed from the cuts here given; and they are rendered still more

Bill of the Peregrine Falcon (Falco peregrinus).

formidable by the organisation of the whole animal, which is calculated to give them the greatest possible effect. The nails or claws, to be available, must be sharp; and in order that they may be kept in this state and fit for duty, there is a provision to enable the bird to prevent them from coming in contact with the ground or other foreign hard bodies; for the claws are retractile, not indeed in the same

Breast-bone of the Peregrine Falcon reduced. clavicles; e, the scapula broken off. a, the sternum; b, the keel; c, the furcula, or os furcatorius; dd, the

breadth of the sternum, the depth of the keel, as well as the strength of the clavicles; and the power of flight peculiar to all the species of true falcons is still further illustrated by the form and substance of the os furcatorius, which is circular, broad, and strong, affording a permanent support to the shoulders. That the long and acuminated form of the wing in the true falcons, with each feather narrow, firm in consistence, the second the longest, and all gradually tapering to a point, is also best adapted for rapidity of motion, may be inferred from the example in the various species of the genera Hirundo, Scolopax, Tringa, Charadrius, Procellaria, Sterna, &c.; but that extent of surface and this peculiarity of form in the wing are not in themselves sufficient alone to afford rapid flight, is proved in the genus Larus, the species of which, though capable of exercising their immense pinions with graceful ease for hours in succession, without any apparent lassitude, are still incapable of rapid flight, for want of strong pectoral muscles. The numerous examples also furnished by the Gallinaceous tribe sufficiently evince that immense pectoral muscles are insufficient when coupled with a small round wing, and afford but a short flight, sustained with great labour, rapid in a small proportion only to the strength and repetition of the impulse, and accompanied by a vibration too well known to need further remark. So material also is the perfection of the feather in the genus Falco, that when any of those of the wing or tail are broken, the flight of the bird is so injured that falconers find it necessary to repair them. For this purpose they are always provided with pinion and tail