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cayed trunk, raises the feathers of its body, in the manner of a turkey-cock, draws its head towards its tail, erecting the feathers of the latter at the same time, and raising its ruff around the neck, suffers its wings to droop and struts about on the log. A few moments elapse, when the bird draws the whole of its feathers close to its body, and stretching itself out, beats its sides with its wings, in the manner of the domestic cock, but more loudly, and with such rapidity of motion, after a few of the first strokes, as to cause a tremor in the air not unlike the rumbling of distant thunder. In perfectly calm weather, it may be heard at the distance of two hundred yards, but might be supposed to proceed from a much greater distance. The female, which never drums, flies directly to the place where the male is thus engaged, and on approaching him, opens her wings before him, balances her body to the right and left, and then receives his caresses.' , * ** I have shot many a fine cock by imitating the sound of its own wings striking against the body, which I did by beating a large inflated bullock's bladder with a stick, keeping up as much as possible the same time as that in which the bird beats. At the sound produced by the bladder and the stick, the male grouse, inflamed with jealousy, has flown directly towards me, when, being prepared, I have easily shot it.'

The pairing time in April is succeeded by the nidification in the early part of May. The root of a bush, the side of a fallen log, or some other sheltered nook in the thickest part of the woods, is selected by the hen, and there she forms a rude nest of withered leaves and grass on the ground. The eggs, from nine to fifteen in number, are of a uniform dull yellowish colour, or brownish-white, and are nearly as large as those of a pullet. As soon as the young are out of the shell they begin to run about, and are conducted by the mother, clucking as she goes, very much like the domestic hen. Like her, too, at night and in bad weather, she covers her young ones beneath her wings, and in a week or ten days they begin to try their powers of flight.

The manoeuvres of this affectionate mother to decoy the intruder from the spot where her young are concealed, by counterfeiting lameness and by mimicry of distress, are well known; but Wilson gives a particular instance of deviation from the usual course of proceeding in such cases, adapted to a peculiar occasion, well worth the consideration of those who are in the habit of considering that faculty which is termed instinct in animals.

'I once started,' says Wilson, a hen pheasant with a single young one, seemingly only a few days old; there might have been more, but I observed only this one. The mother fluttered before me for a moment; but suddenly darting towards the young one, seized it in her bill, and flew off along the surface through the woods, with great steadiness and rapidity, till she was beyond my sight, leaving me in great surprise at the incident. I made a very close and active search around the spot for the rest, but without success.' * * 'Here,' continues our author, 'was a striking instance of something more than what is termed blind instinct, in this remarkable deviation from her usual manœuvres when she has a numerous brood. It would have been impossible for me to have injured this affectionate mother, who had exhibited such an example of presence of mind, reason, and sound judgment, as must have convinced the most bigoted advocates of mere instinct. To carry off a whole brood in this manner would be impossible, and to attempt to save one at the expense of the rest would be unnatural. She, therefore, usually takes the only possible mode of saving them in that case, by decoying the person in pursuit of herself, by such a natural imitation of lameness as to impose on most people. But here in the case of a single solitary young one, she instantly altered her plan, and adopted the most simple and effectual means for its preservation.'

The ruffed grouse is surrounded by enemies. In addition to the common persecutor man, the different species of hawks are on the watch for these birds, and particularly the red-tailed hawk and the Stanley hawk, according to Audubon. The former of these hawks, silently perched on the tops of trees, seizes his opportunity and dashes irresistibly down upon them; the latter, gliding rapidly through the woods, pounces upon them before they are aware of their danger. Among the quadrupeds, pole-cats, weasels, racoons, opossums, and foxes, are said by the same author to be destructive foes to them.

The following is Dr. Richardson's description of a male killed on the 4th May, on the Saskatchewan plains: Colour. Back, rump, and upper tail coverts chestnutbrown, mottled and finely undulated with blackish-brown; the broad tips and a cordiform central mark on each feather pale-grey. Back of the neck, scapulars, and wing-coverts having the same colours, but the grey tips very narrow, the blackish-brown in large blotches, and instead of central marks, stripes along the shafts of orange-brown and brownish-white. Top and sides of the head, the tertiaries, and outer edges of the secondaries, mottled with the same. Eye stripe from the nostrils whitish. Shoulder-tufts velvetblack, glossed with dark-green. Quills liver-brown, the outer webs barred near the base and mottled towards the tips with cream-yellow. Tail grey, finely undulated, and also crossed by about nine narrow bars and a broad subterminal one of blackish-brown. Under plumage:-throat and breast yellowish-brown, belly and vent brownish-white; all remotely barred, but most broadly on the sides of the belly, with blackish-brown, which also forms a band across the upper part of the breast between the ruffs. Inner wings coverts and axillaries clove-brown, barred and tipped with white. Bill and nails dark horn-colour. A male killed at the same time with the preceding, and of equal dimensions, shows more of the chestnut or orange-brown in its plumage, and the ground colour of its tail is yellowish-brown, the extreme tips and a bar next the broad subterminal dark one being grey.

Females have less of the blackish-brown colour; the shoulder tufts are orange-brown instead of black; and the subterminal bar on the tail is chestnut-coloured. Young birds. In these orange-brown is the prevailing tint of colour.

Form.-A short crest on the top of the head: a fringed comb over the eye in the male. Shoulder tufts consisting of about fifteen fan-shaped feathers. Fourth quill the longest, slightly exceeding the third and fifth. Tail fanshaped, of eighteen feathers, the central pair more than half an inch longer than the outer ones: the individual feathers nearly square at the end. Tarsus feathered more than halfway down anteriorly, and about half an inch lower posteriorly. All the toes strongly pectinated.

The dimensions, on an average, may be taken as eighteen inches in length, and twenty-three or twenty-four in extent.

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VOL. V.-U

Dr. Richardson states that, after a careful comparison of the specimens of Mr. Douglas's Tetrao Sabini, deposited in the Edinburgh Museum, they appeared to differ in no respect from the young of Tetrao Umbellus (Bonasia), and that the characters by which Mr. Douglas distinguishes his bird are equally applicable to the latter.

Douglas, whose premature and violent death we have to deplore in common with all who are interested in the progress of natural history, found in the valleys of the Rocky | Mountains, 54° N. lat, and a few miles northward, near the sources of Peace River, a supposed variety of Bonasia | Umbellus. On comparing his specimens from that country with some which he prepared in the States of New York and Pennsylvania, and on the shores on the chain of lakes in Upper Canada, he found the following differences :First, the northern bird was constantly one-third smaller, of a very light speckled mixed grey, having little of that rusty colour so conspicuous in the southern bird :-secondly, the ruffle consists invariably of only twenty feathers, short, black, and with but little azure glossiness; the crest feathers were few and short. Should these characters,' adds the author, hereafter be considered of sufficient importance for constituting a distinct species, it might perhaps be well to call it Tetrao umbelloïdes.'

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Whether the bird above described be variety or species, it would certainly belong to Bonaparte's subgenus Bonasia. We cannot conclude this article without earnestly pressing upon the consideration of those who are interested in such subjects, the ease with which the ruffed grouse might be added to the Fauna of Europe; and we entirely agree with Audubon, that in England and Scotland there are thousands of situations perfectly suited to the habits of this noble species of game. Audubon even goes so far as to say that he has not a doubt that a few years of attention would be sufficient to render them quite as common as the grey partridge; and we hope that this hint will not be lost on the sportsmen of Great Britain.

BONASO'NI, GIULIO, a native of Bologna. The precise date of his birth is unknown, but it was probably about 1498; the date of his death is equally uncertain; we only know that he was alive in 1572. It is conjectured, but without sufficient authority, that he studied painting under Lorenzo Sabbatini. The few of his productions that remain do not exhibit any extraordinary power. As an engraver he is excelled by few, for though we should now consider him very defective in the mechanical treatment of the plate, he worked with the gusto of a genuine artist. He wrought almost entirely with the burin; and if he fails occasionally in the outline, he always catches the spirit of his original. His copies are so free, and yet so delicate and expressive, that they might be taken for original designs. His back grounds are flat and hard, his drawing sometimes uncertain, and his handling frequently very harsh; but there is so much grace and delicacy in his females and children---so much activity in his young men and majesty in the elder-so fine a breadth of light and shade-so forcible is the expression of his heads,—that his versions of the great works which he copied are more valuable than those of many later and more dexterous artists. He has engraved from the works of Raphael, Michel Angelo, Titian, Parmigiano, and many of the great painters; for he displayed his taste as much in the choice of his subjects as in the execution. He has left many engravings from original designs which are characterized by much grace and agreeable simplicity, but are wanting in force, and rather scattered in the grouping. Many of his works are very scarce. (Malvasia; Lanzi; Strutt; Cumberland.)

BONASSUS. [BISON.]

BONAVENTURA, ST., was born at Bagnorea in 1221. At twenty-one years of age he became a friar of the Order of St. Francis, and was sent by his superiors to Paris. He, as well as Thomas Aquinas, of the Dominican Order, be- | came involved in contentions with the University of Paris, which denied the academical honours, as well as the exercise of public professorship, to individuals of the mendicant orders. Pope Alexander IV., being appealed to, summoned the parties before him at Anagni. _The mendicant orders chose Bonaventura and Albertus Magnus to plead their

Linn. Trans. vol. xvi. p. 137. But it should be remembered that Dou glas describes the eggs of his Tetrao Sabini to be dingy white with red spots; whereas the eggs of Bonasia Umbellus are described as being spotless. The reader should however be aware that the eggs of different individuals of the same species often vary considerably in their markings.

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cause. The pope gave sentence in their favour, but still the Parisian university refused to grant the laurea to Bonaventura and Thomas Aquinas, and Gerard of Abbeville wrote in an abusive strain against the mendicant orders. Bonaventura replied to him powerfully, though temperately, in his Apologia Pauperum.' At last, in 1257, a sort of compromise took place, and Bonaventura received his doctor's degree. He had already been elected general of his order, in which capacity he enforced a strict discipline, giving himself the first example of implicit adherence to the monastic rules and regulations. He wrote upon this subject Epistola encyclica ad Ministros Provinciales et Custodes,' and Determinationes Quæstionum circa Regulam Sancti Francisci. He then retired to the convent on Mount Alvernia in Tuscany, where he wrote Vita Sancti Francisci,' and also an ascetic work, Itinerarium Mentis in Deum,' for which last he received the appellation of the Seraphic Doctor.' On the death of Pope Clement IV. in 1268, the cardinals could not agree for a long time in the choice of his successor, and the see of Rome had remained vacant for nearly three years, when Bonaventura succeeded by his eloquent exhortations in reconciling their differences and producing unanimity of votes in favour of Tedaldus Visconti, afterwards Gregory X. The new pope appointed Bonaventura Bishop of Albano, and took him with him to the council of Lyons. Bonaventura was actively engaged in the labours of the council when he was stopped by death in 1274. His funeral was attended by the pope, the cardinals, the patriarchs of Constantinople and of Antioch, and by more than 500 bishops. His character for sanctity was already established in the popular opinion, and Dante, who wrote not many years after his death, places him among the saints in canto 12 of the 'Paradiso.' Bonaventura was afterwards regularly canonized by the church. His works have been collected in 9 vols. folio, Rome, 1588, and 13 vols. 4to. Venice, 1751, to which last edition a well-written life of Bonaventura is prefixed. He has been praised for having avoided scholastic cavils and ambiguities in his style, and for having spoken the language of earnest faith and sincere piety: such is the opinion of Brucker and of Condillac. Luther placed Bonaventura above all scholastic theologians. Several works have been attributed to Bonaventura which do not belong to him, but which have furnished an opportunity to Voltaire and other critics for throwing ridicule upon the supposed author. (Dissertatio De Suppositiis and Life of Bonaventura, prefixed to the Venice edition of his works.)

BONAVISTA, or BOAVISTA, the most easterly and one of the largest of the Cape Verde Islands, lies 21 miles S. of Sal, and 300 miles W. by N. of Cape Verde, the nearest point of the African coast. It was so called from the beautiful appearance it presented to the first discoverers (the Portuguese) in 1450, and, from all accounts, was formerly more fertile than it now is. The island is generally a low plain, with some elevated parts near the centre. Salt is the principal article of trade, which the inhabitants exchange for clothing and necessaries. Pigs, goats, sheep, and poultry may also be had, but they are all lean, and of an inferior quality. The town is on the western side of the island, and consists only of about forty or fifty houses, mostly built by negroes, and rudely constructed. The population of the island in 1822 was estimated at about 3000, of whom 300 are regular soldiers. The colour of the inhabitants is of all the intermediate shades from white to negro jet, owing to intermarriage.

Bonavista is of an irregular shape, nearly octagonal, sixteen miles in length, N. and S., and the same in breadth: it is surrounded by many rocks and shoals. There are two anchorages, one off the town, called English Road, and the other off the S.E. point, called Portuguese Road; of these the former is the more secure, and is perfectly safe in the summer months when the N.E. trade blows constantly. Sixteen miles to the S.W. is a very dangerous rock called the Leton Rock, about a mile in extent, nearly level with the water's edge, and with deep water round it. The town lies in 16 9 N. lat., and 22° 57′ W. long.

(North Atlantic Memoir, &c.)

BOND. A bond or obligation, in law, is a deed by which he who makes it, called the obligor, binds himself to another called the obligee, to pay a sum of money, or to do, or not to do, any other act. It is, in fact, a species of covenant. [COVENANT.]

Bonds for the payment of money are the most commen,

They are employed instead of promises by word, or by un- secured. But the Courts of Equity consider the condition
sealed writing, for the following reasons. First, a bond of every penal bond to be evidence of an agreement on the
(like every covenant) to pay a sum of money may be en- part of the obligor to perform the duty whose performance
forced against the obligor, although no legal motive or con- is to relieve him from the penalty. Thus a condition for
sideration existed for making it (which is not the case with making a bond void in case the obligor does or does not do
a verbal promise or a promissory note for its payment), for a any act, shows, in contemplation of equity, an agreement
deed cannot be set aside by the maker of it, though gra- by him to do or not to do such act; and this agreement
tuitous. Hence, voluntary engagements which are in-will, in many cases, be enforced against him, at the suit of
tended to be binding in law should be made by bond or the obligee, by a decree for specific performance of the
covenant. Secondly, though the sum of money which a agreement, or by an injunction against its breach; and
person is to oblige himself to pay is a debt already existing, thus, even where the penalty in a bond is insufficient, the
or though any legal consideration for its payment exists, so obligee is not always without remedy.
that a promise by word or by unsealed writing to pay it
would be binding in law, yet a bond is a better security;
for if the debtor dies before the debt, though due, is paid,
the creditor being, by virtue of the bond, among those who
are called creditors by specialty, will be entitled to be satis-
fied out of the personal, and real assets [ASSETS] of the de-
ceased before creditors by simple contract (among whom,
if he had only the verbal promise or promissory note of his
debtor, he would be reckoned) receive any part of the debts
due to them. (2 Bl. Com. 340. 511. Stat. 1 W. IV. c. 47.
3 and 4 W. IV. c. 104.) In order, however, that a bond
debt may be thus payable out of the real assets of the
debtor (his lands of which he died seized) before his simple
contract debts, the debtor must, by the bond, have ex-
pressly bound himself and his heirs to pay the debt.

Another advantage which a bond has over a bill of exchange or promissory note is that an action may be brought upon it at any time within twenty years after it is due (Stat, 3 and 4 W. IV. c. 42, s. 3); whereas a simple contract debt is barred by the statute of limitations after six years. [LIMITATION.]

A bond, though thus a better security in many respects than a promissory note or bill of exchange, is inferior to them in one particular; for it cannot be assigned in law, so as to give the assignee the right of suing, in his own name, the obligor for the debt. (2 Bl. Com. 442.) The courts of equity, however, support, as far as they can, assignments of bonds to purchasers, and acknowledge and enforce the right of such assignees to receive the bond debts out of the assets of the debtors.

The courts of Law do not consider that an implied covenant is created by the condition of a bond, so as to allow the obligee to bring an action upon it; but they, as well as those of equity, so far take the condition to be evidence of a contract upon which the bond is founded, as to hold the bond to be void, if the condition is unlawful. For though, as before said, a bond without consideration may be valid, yet a bond made for an unlawful consideration, or upon an unlawful contract, is void, like every other deed so circumstanced.

Penal bonds have almost superseded, in general use, bonds without condition, or single bonds. Even when a bond is intended to secure the payment of money, the constant practice is to make it in the form of a bond for payment of a penal sum, double the principal sum which is really to be paid, with a condition, making the bond defeasible upon the latter sum being duly paid with interest. The chief advantage of such a bond over a single bond was, not that any more money than was fairly due to the obligee could or can be recovered under it (for the stat. 4 and 5 Ann, c. 16, forbids that), but that full interest, up to the day on which the debt was satisfied, might be obtained, if within the penalty; whereas, under a single bond for payment of the principal and interest at a certain day, no interest beyond that day could be claimed. That defect of the single bond, however, is supplied by stat, 3 and 4 W. IV., c. 42, s. 28.

A bond is sometimes made by or to several persons together. In such case, the bond may have different effects, according as it is prepared, as either a joint bond, a several bond, or a joint and several bond. This distinction applies equally to covenants, and is noticed under that title. [COVENANT.]

The several modes in which a bond may be discharged (when not actually satisfied) may also be learned by referring to the same title; where the principal rules relating to the discharge of covenants, which equally apply to bonds, are mentioned.

A bond is so good a security for the payment of a sum of money, that it is often employed not only when a debt is to be established, but when a pecuniary penalty is to be provided. When a man is required to oblige himself to do or not to do any act, he often enters into a bond for payment of a certain sum of money, as a penalty, in case he departs from his agreement. A bond of this kind, which is called a penal bond, is always prepared as follows. It is a simple bond for payment of the penal sum, no time BONE, a living organ of complex structure, forming in or event being mentioned when that shall be due: but a the higher animals the basis of the fabric of the body. The condition is added for making the bond void, in case the creatures placed at the bottom of the animal scale, comobligor performs his duty; the nature of such duty being posed of soft gelatinous matter and buoyant in water, need expressed in the condition. This may seem not to be the no solid support; but all animals that possess solid organs, most accurate mode of securing a contingent penalty; but, and whose body rests upon particular points, must have construed by law, such a bond answers its purpose. For some substance of a dense and inflexible nature to afford to though, generally, when a bond for payment of a sum those various tissues and structures the requisite resistance of money mentions no time of payment, an action may be and support. Throughout the animal kingdom the subbrought upon it immediately; yet in this case the penal sumstances that serve this purpose are the salts of lime, someis not considered to be due or recoverable till the condition times the carbonate, sometimes the phosphate, and at other annexed to the bond fails of effect by the obligor neglecting times both combined in different proportions. When in or departing from his duty. These penal bonds are further the composition of the solid support of the body the carborendered equitable in their operation by the liberal con- nate of lime predominates, it constitutes the substance called struction which the law puts upon the conditions annexed shell; when there is a greater proportion of the phosphate to them; often holding that such conditions take effect, and it is called a crust, as in the coverings of the lobster, the that their terms have been sufficiently observed, when, ac- crab, and so on; but when the earthy matter consists alcording to a more rigid construction, the penalties would most wholly of the phosphate it constitutes bone. have been forfeited; and often restraining obligees from taking advantage of the failure of such conditions, when they ought not, in justice, to receive the penalties. Even when the obligee in a penal bond is allowed to recover the penalty, he cannot, generally, take any more of it than what is a reasonable compensation for the damage sustained by him; and the amount of such compensation will be ascertained by the verdict of a jury. (Stat. 8 and 9 W. III. c. 11.)

The obligor in a penal bond being thus protected, it may seem that equal relief should be given to the obligee, when the penalty is not, as usual, greater than the amount of damage sustained by him, but less. However, it is a general rule, that the obligee cannot recover upon his bond any pecuniary compensation beyond the penal sum expressly

When an animal possesses bone as the solid support of its fabric, it indicates a high degree in the scale of organization. Bone is an elaborate structure found in no class below the vertebrata. Even the lowest order of this, which is the highest class of animals, is wholly destitute of it; for it is not found in large tribes of fishes, the shark, the sturgeon, the ray, &c. In these, the less highly organized substance called cartilage is substituted, and accordingly these fishes are called cartilaginous, in contradistinction to the osseous; and in all classes below the cartilaginous fishes, the dense and inflexible substance which sustains the soft parts of the body, and which affords points of resistance for the action of those parts, consists either of shell or crust, or of some modification of these inorganic matters, and not of true organized bone.

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In general the inorganic matter which performs the office | the animal membrane, and yet strong enough to dissolve of bone in the lower animals is placed on the exterior of the the phosphate of lime,-if for this purpose it be macerated in body, and often indeed forms its external envelope; true diluted nitric or muriatic acid,-every particle of the phosbone, on the contrary, is always placed in the interior. phate of lime may be removed, and the animal matter alone Even when it approaches the surface, bone is always covered will remain perfectly uninjured and unaltered. Accordingly, by some soft part, as muscle, membrane, skin, &c. Crust, the remaining substance retains the exact figure and dimenshell, horn, the substances which form the skeleton of the sions of the original bone, but it has lost all its other meinferior animals, are thus external, the soft parts being chanical properties. It is so soft and flexible, that if either internal; but in the higher animals the skeleton is always of the long bones of the human arm, that for example called internal, and the soft parts, which are sustained by it, and the radius, be treated in this manner, it can with the utwhich re-act upon it, are external. most ease be tied in a knot. By the first process the earth The office of bone in the animal economy is chiefly me- is obtained, deprived of its animal constituent; by the chanical, and the mechanical purposes to which it is sub-second, the membranous matter free from the earth. In the servient require that it should be of different sizes and bone both are combined; in every constituent atom of it forms. In the human skeleton there are commonly enu- there is an earthy in intimate combination with an animal merated 260 different bones, which present every variety matter. The first gives it hardness; the second tenacity; of size and figure. But all these varieties may be re- and thus by the intimate combination of these elements two duced to three classes: the long and round, as the bones of qualities, which in unorganized matter are scarcely comthe upper and lower extremities: the broad and flat, as the patible, are combined. By increasing the proportion of bones of the skull; or the short and square, as the separate phosphate of lime any degree of hardness can be obtained: bones that compose the vertebral column. The long bones the bony portions of the ear, the bony portions of the teeth, are adapted for motion, the flat for protection, and the for example, are as hard as marble, or even flint; but subsquare for motion combined with strength. Accordingly stances so hard would not do for the ordinary purposes of the long bones, which are adapted to communicate a free bone, because they would be brittle in proportion to their range of motion, are moulded into lengthened cylinders, hardness, and would be productive of fatal mischief whenand form so many levers, constituting organs of locomotion, ever they were subject to any sudden and violent concusexquisitely constructed and combined for the accomplish- sion. But all evils of this kind are effectually guarded ment of their office, as is seen in the fin of the fish, in the against by the elastic matter which is the basis of the strucwing of the bird, and in the limb of the quadruped. In the ture, and not only acts as a strong cement interposed beemployment of the flat bones for the covering of some of tween the calcareous particles, but, by the increase of its the more tender and delicate organs, as the brain and spinal relative proportion, is capable of modifying the rigidity of cord, the form of these bones is such as to add to their the earthy matter to any extent. strength, as is manifest in the vaulted roof of the skull; while in the construction of the vertebral column, composed of the short and square bones, which are so adjusted as to afford a limited range of motion with a great degree of strength, so many and such opposite purposes are effected, by means so simple yet so efficient, that no fabric constructed by human ingenuity approaches the perfection of this admirable piece of mechanism.

Bones not only differ so much from one another in their comparative hardness, according to the office which each has to serve, that no two bones possess the same degree of rigidity, but no bone is equally hard in its entire substance. When a section of a bone is made in such a manner as to show its structure throughout, it is seen to consist of two varieties, a hard or compact, and an alveolar or spongy substance. In general the compact forms the external and the part of the bone forms a completely solid body, exhibiting scarcely any visible arrangement, without apparent fibres and laminæ; but towards the inner part of the bone the substance becomes less and less dense, until at length it presents the appearance of minute and delicate fibres, which intersect each other in every direction, forming the cells termed cancelli (lattice-work). The transition from the compact to the spongy or cancellated part is not marked by any distinct boundary; the one passes into the other by insensible degrees, showing that there is no essential difference between them; and indeed the evidence is complete, that, although in the densest part of the bone there is scarcely any trace of specific organization, it is made up of fibres and plates perfectly similar to those of the spongy or cancellated part, differing from it principally in its greater degree of condensation. Often in the centre of the bone there is scarcely any even of the spongy matter, but a hollow space is left, which is filled up with a series of membranous cells in which the substance called marrow is lodged.

The structure, disposition, and connexion of the indi-spongy the internal portion of the bone: the compactest vidual bones accomplish in the most perfect manner the following mechanical uses:-1. By their hardness and firmness they afford a support to the soft parts, forming pillars to which the more delicate and flexible organs are attached, and kept in their relative positions. 2. By the same properties of hardness and firmness they defend the soft and tender organs, by forming solid and strong cases in which such organs are lodged and protected, as the case formed by the bones of the cranium for the lodgment and protection of the brain; by the bones of the vertebral column for the lodgment and protection of the spinal cord; and by the bones of the thorax, for the lodgment and protection of the lungs, the heart, and the great vessels connected with it. 3. By affording fixed points for the action of the muscles, and by assisting in the formation of joints, they aid and are indeed indispensable adjuncts to the muscles in accomplishing the function of locomotion.

Bone is a complex organ, and the arrangement and combination of its constituent parts are highly curious. It is composed essentially of two distinct substances, an animal and an earthy matter. The animal matter is analogous, both in its nature and in its arrangement, to cellular membrane; the earthy matter consists of phosphoric acid combined with lime, forming phosphate of lime. The cellular membrane is aggregated into plates or laminæ, superimposed one upon another, leaving between them interspaces or cells, in which is deposited the earthy matter, phosphate of lime.

This structure of bone is rendered manifest by subjecting it to certain chemical processes. If a bone be placed in a charcoal fire, and the heat be gradually raised to whiteness, it appears, on cooling, as white as chalk; it is extremely brittle; it has lost very much of its weight, yet its bulk and shape are little changed. In this case the membranous matter is wholly consumed by the fire, while the earth is left unaltered. Over the surface of a bone so treated are visible a number of minute crevices, the spaces which were filled, in the natural state of the bone, with the animal matter; and on breaking the bone across, the size and shape of the cavities which contained the marrow be come manifest. If, on the other hand, the same bone be placed in an acid sufficiently diluted to prevent its injuring

In the arrangement of the fibres in different bones, so as to adapt them to the specific offices they have to serve, there is exquisite mechanism. Where the principal object is either extensive protection, or the provision of broad surfaces for the attachment of muscles, the osseous fibres are so disposed as to form flattened plates, as in the bones of the skull. When, on the other hand, a system of levers is wanted, as in the limbs which have to sustain the weight of the trunk, and to confer extensive powers of locomotion, the bones are modelled into lengthened cylinders, generally somewhat expanded at the extremities for greater convenience of mutual connexion. The shank or body of this hollow cylinder consists principally of compact with but little spongy matter, while the extremity or head of it is principally composed, of spongy matter, with only a thin crust of compact substance. The principal mechanical property required in every cylindrical lever is rigidity, and more especially the power of resisting forces applied transversely, that is, tending to break the cylinder across it has been often stated that a given quantity of materials could not possibly have been disposed in a manner better calculated for such resistance than those in the form of a tube or hollow cylinder. The hollow stems of vegetables derive their chief strength from

possessing this form. Bones also are rendered both lighter and stronger by being made hollow than if the cylinder had been solid; and as it is in the middle of the shaft that the strain is greatest, so it is here that the cavity is largest and the resistance most effectual.

The chemical composition of bone may be easily understood from the preceding statements. The earthy salt is the phosphate of lime; the animal matter is condensed albumen. Albumen constitutes the basis of membranous matter of all descriptions. As it actually exists in bone, it bears a close resemblance to cartilage, and is probably identical with it. Into the composition of bone there likewise enters a quantity of jelly, which may be extracted from it by boiling, and the younger the animal the larger is the proportion of jelly.

It has been stated that the central cavities of some of the larger bones are filled with the substance called marrow, an oily matter contained in a series of membranous cells, which, like those in which the fat is deposited [ADIPOSE TISSUE], do not communicate with each other. Even the pores and cancelli of bone also contain a kind of oily matter, which is supposed to differ from marrow only in possessing a greater degree of fluidity. This oily matter is deposited in longitudinal canals, which pass through the solid substance of the bone, together with its nutrient vessels. The use of the marrow, and of the modification of it which constitutes the oily matter, is not well understood. Without doubt it serves the same general use in the economy as the other oily secretions. [ADIPOSE TISSUE.]

All bones are covered by a membrane named, on account of its affording them an external envelope, periosteum. The outer surface of this enveloping membrane is connected to the surrounding parts by cellular tissue, but its inner surface is firmly adherent to the substance of the bone. This adhesion is effected by innumerable fibres or threads, which on examination are found to consist of blood-vessels. The periosteum is in fact the membrane on which the nutrient arteries of the bone rest, divide, and ramify in order to enter the osseous substance. These threads are much more numerous in the child than in the adult; and accordingly the adhesion of the periosteum to the bone is much firmer in the former than in the latter, as the quantity of blood distributed to the bone is greater. Moreover, in general the inner surface of bones is also lined by a fine and delicate membrane, commonly termed the internal periosteum, the continuation of which forms the membranous bags in which the marrow is contained.

Great attention has been paid to the phenomena attending the growth of bone, and the facts ascertained relative to its progressive development are not only interesting and important in their own nature, but afford a singular confirmation of the correctness of the preceding statements as to its general structure. If the human embryo be examined at a very early period of its existence, that is, about the seventh or eighth week after conception, the parts destined to become bone are found soft, gelatinous, and semi-fluid; but the figure of several of the larger bones can already be distinctly traced. As yet there is not a particle of bone contained in these gelatinous masses, nor anything approaching the consistence of a solid compact substance. It is merely a semi-fluid matter contained in a delicate membrane. The newly-formed arteries of the system, by the agency of which the different structures are to be developed, gradually extending over the nascent organization, those arteries which are to form bone at length arrive at these pulpy masses. By degrees these masses are observed to acquire more consistence; and at length pass from a soft and semi-fluid state into that of a solid and firm substance, which assumes the appearance and exhibits the properties of cartilage. This cartilage, at first transparent and colourless, after some time exhibits in different parts of its surface opaque whitish spots. These spots, when examined by the microscope, are found to consist of a number of delicate lines, which progressively increase in size and density. Red points are also seen to be dispersed through them, indicating that the blood-vessels of the parts are so much enlarged as to be capable of admitting the red particles of the blood; and now particles of bone are copiously and rapidly deposited, insomuch that the parts which were recently hard and elastic soon become hard and rigid, and this rigidity increases to such a degree that the blood seems to be scarcely capable of forcing a passage through its vessels, compressed as they are by the dense matter which accumulates around them in all directions.

Thus the first animal matter that forms the basis of bone appears to be jelly; for jelly albumen, a more highly organized substance, is soon substituted; as the process of ossification advances, the proportion of jelly gradually diminishes, while that of albumen increases. The first deposition of bony particles takes place in cartilage; this cartilage, which forms the earliest deposit or nidus of the bony particles, does not remain as a permanent part of bone, but is carried away by the absorbent vessels as the osseous matter continues to be deposited, and this first-formed cartilage is replaced by a totally new deposition of animal matter, namely, the membranous substance which subsequently forms a constituent part of bone.

Such is the process of ossification, in regard to which it has been justly and beautifully said by Dr. Roget, that as sculptors, before working upon the marble, first execute a model of a coarser and more plastic material, so the first business of the arteries is to prepare a model of the future bone, constructed, not with the same material of which it is afterwards to consist, but with another of a simpler and softer nature, namely cartilage. Until the other parts of the fabric have proceeded so far in their development as to have acquired a certain degree of solidity and firmness, and to bear as well as to require the support of more massive and rigid structures, this flexible and elastic cartilage may be employed with great advantage as its substitute. A hard and unyielding structure would, in the early stages of its formation, have even been injurious. But in proportion as the fabric is enlarged, the necessity for mechanical support increases, and further provision must be made for resistance to external violence. The removal of the cartilage may be compared to the taking down of the scaffolding which had been erected for the intended building. But this scaffolding is not taken down at once; each part is carried away piece by piece, as the operation of fixing in their position the beams and pillars of the edifice proceeds. The way is cleared at first by the absorption of the central part of the cartilage, and a few particles of ossific matter are deposited in its room. Greater activity is now displayed in the arteries, which rapidly enlarge in diameter, assume more active functions, and hasten to execute their task by depositing granules of calcareous phosphate: these are laid down particle by particle, in a certain determinate order, and in regular lines, so as to form continuous fibres. When a great number of these delicate fibres are gathered together, and connected by other fibres, which shoot in various directions across them, a texture composed of an assemblage of long spicula or thin plates is constituted. In the cylindrical bones the spicula prevail, and are arranged longitudinally, parallel to one another and to the axis of the bone. In the flat bones the fibres have a radiated arrangement, shooting out from the spot where the first deposit took place as from a common centre. The union of the fibres as they proceed from different centres is not indiscriminate, but is regulated by definite laws. Each distinct bone is formed from a certain number of ossific centres, which altogether constitute a system appertaining to that bone only, and not extending to the adjacent bones. These pieces unite together as if by a natural affinity, and they refuse to unite with the bony fibres proceeding from neighbouring centres and belonging to other groups.

Were this the whole of what takes place in the formation of a bone, the process would not perhaps differ very materially from that by which a shell is produced; for a shell is the result of successive depositions of calcareous matter, forming one layer after another, in union with a corresponding deposit of animal membrane. But the subsequent changes which occur show that the constitution of bone is totally dissimilar to that of shell; for no portion of the shell that is once formed and has not been removed is subject to any further alteration. It is a dead though perhaps not wholly inorganic mass; appended indeed to the living system, but placed beyond the sphere of its influence. But a bone continues during the whole of life to be an integrant part of the system, partaking of its changes, modified by its powers, and undergoing continual alterations of shape, and even renewal of substance, by the actions of the living vessels.

The form which had at first been rudely sketched slowly advances towards perfection in the course of its growth, and the general proportions of the parts are still preserved, the finished bone exhibiting prominences and depressions in the same relative situation as at first, and not only having

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