ANATOMY never be forgotten: he furnishes a noble and rare example of a man who, as soon as he had rendered himself independent by his own exertion, in a laborious and difficult profession, applied the whole of his large income to a great public object; and, though thwarted in his original desire, that it should remain in the metropolis in which the fortune expended upon it had been amassed, as a monument of his gratitude and an example to his successors, he was, nevertheless, sufficiently liberal and patriotic to devote it to the use of the public, by bequeathing it to the university which had granted him his degree. importance of anatomy as the basis of medical, We have dwelt upon the Hunterian School, Human anatomy is usually subdivided into descriptive and morbid, or, more correctly, pathological. with their relative situations and connections; it examines the textures of which they are formed, enumerates the nerves and vessels by which they are supplied, and gives all general and particular details concerning their organisation. Having done this, it proceeds to the analogies that subsist among the materials of which different organs are composed; and is thus led to specify the proximate constituent parts of the living body. Morbid or Pathological Anatomy comprehends all that relates to the effects of disease upon healthy structures; and carefully traces and describes the changes of texture and of composition which they thus suffer, in reference to the entire organ, as well as to its individual parts. Dr. Hunter not only gave a new impulse to anatomical science, the effects of which have been transmitted to the present time, but his zeal in behalf of his favourite pursuit tended to make many converts. Among these, the celeDescriptive Anatomy embraces a description brated John Hunter stands foremost. Hearing of his brother's reputation, he offered his of the different organs of the body, together services as an assistant in his inquiries, and his proposal was kindly accepted. Accordingly, in September 1748, he left Lanarkshire, being then twenty years of age. His disposition to excel in anatomical pursuits soon became evident. In the course of the succeeding year he had rendered himself sufficiently master of the subject to instruct his brother's pupils in the dissecting-room; and in 1755 was admitted to a partnership in the lectures. His ardour and enthusiasm as an anatomist were most extraordinary, and he became as eminent in surgery as his brother was in physic: yet his more lucrative professional avocations were never allowed to supersede his scientific zeal; and the result was, the formation of a Museum of Comparative Anatomy, which is at once a memorial of a scientific mind and a skilful hand. Mr. Hunter died suddenly on October 16, 1793, at the age of 65. He directed by his will that his Museum, upon which he had expended nearly the whole of his large professional income, should be offered to the purchase of Government; and, fortunately for the credit of our country, the proposal met with a very different reception to that which we have above recorded in reference to his brother. It was purchased for the sum of 15,000l., and made over, under certain conditions, which have been not only faithfully, but liberally, fulfilled, to the Royal College of Surgeons, in London. It is one of the most splendid collections in the world, and in many respects unrivalled; it is open, under proper regulations, to public inspection, in the magnificent building erected by the College for its reception, on the south side of Lincoln's Inn Fields. Another convert to anatomical pursuits, educated in the school of William Hunter, was his nephew, the late Matthew Baillie. His virtues and his talents placed him high in public estimation; his anatomical knowledge was the foundation of his professional eminence; and the excellence of his lectures, both as regards matter and manner, tended to exalt the reputation of his uncle's school, and to establish the 93 We shall now proceed to give a short description of the parts of which the human body is constructed, referring for the account of individual organs to the separate terms under which they are enumerated. Anatomical teachers generally first direct the student's attention to that branch of the subject which is termed Osteology; in other words, to the bones or skeleton, constituting the hardest and most durable part of the whole structure, and that which gives it its stability and general form. At the period of birth, the bones, for obvious reasons, could not exist with the degree of induration and firmness which they possess in the adult; we accordingly find that, at that period, they are mostly soft and flexible, resembling cartilage, with certain specks of osseous matter, which gradually extend and increase, as the process of ossification advances during the growth of the young animal. In contemplating this bony skeleton when it has thus become perfect, we are struck with the admirable adaptation and mutual connection of the various parts of which it consists; the separate bones being extremely numerous (including the teeth, amounting to about 250), and attached to each other by unequal surfaces, the cavities and eminences of which mutually correspond. These connections, termed arti ANATOMY pairs from the brain or spinal marrow, amount to about forty; and in tracing them and their branches, they are found in certain different places to swell into knots, which are termed ganglia, or they are reticularly aggregated into plexuses. Having thus shown how the bones are connected and put into motion, and from what sources their motion is derived, it may next be inquired how they and the other organs of the body grow and are nourished. This brings us to consider the blood and its vessels. culations, are extremely various; some admit-particles. But though the muscles are the ting of every variety of motion, others of immediate organs of motion, they are depenlimited motion, and others, as it were, con- dent for their powers of contraction and tinuously united. In the former case the evils relaxation upon the nerves with which they of friction are perfectly provided against by the are supplied. These, when separately exapeculiarity of the articulating surfaces, which mined, appear in the form of white cords or are covered with an extremely smooth and threads; and, when traced to their origin, are elastic substance, called cartilage; and lubri- found to issue as it were from the brain, and cated, or as it were oiled, by a slippery fluid from its elongation, termed the spinal marrow. termed synovia, which here performs precisely The trunks of the nerves are subdivided into the same office as that of the various anti-attri- branches, and these again into filaments, which tions which are used in machinery. But as the enter into, and are, as it were, lost in the bones must be more or less restricted in their substance of the muscles and other organs of the range of motion, there are peculiar means by body. Their functions are in some cases which that end is attained: some being pre- obedient to, and in others independent of the vented from changing their relative situations will: to the former belong the nerves of the by certain modes of articulation; others, where locomotive muscles; to the latter, those of the a slight motion is required, being united by heart, viscera, &c. When they are divided, cartilage; and others, where extensive and the peculiar functions of the organs which they varied motions are wanted, being connected supply are impaired or impeded: thus, the by ligaments, membranes, or flesh.— Ligaments muscles may be deprived of the power of are white, fibrous, glistening, and flexible sub-contracting, the glands of secretion, the eye of stances, occurring in an infinite variety of sight, the ear of hearing, and the skin of forms and situations. They are, for the most feeling. The nervous trunks, which issue in part, exterior to the joint, and, by their great strength and trifling elasticity, preserve the relative position or connection of the bones in their various movements.- Membranes are thin, whitish webs or textures, more flexible and elastic than ligament. They not only assist in the security and motion of joints, but fulfil a variety of other offices. They surround or line the cavities and the organs of the body, and contribute to unite and combine the whole; and, at the same time, interpose, and preserve a distinction, enabling separate parts either to co-operate or to act independently of each other. They vary in strength and texture, and different terms are applied to them in different parts of the body: two within the skull are called matres; those which envelope muscular fibres are called aponeuroses; that which covers the lungs and lines the cavity of the chest is termed pleura; that which lines the cavity of the abdomen and its included viscera is named peritoneum; those which inclose articular surfaces are termed capsules; that which covers bone, periosteum; and, in other cases, they are called coats, or tunics. The remaining substance concerned in the connection of the bones is flesh: it is thus that the upper extremities are connected with the body, and that many of the joints are rendered secure. But flesh performs another and more important office, inasmuch as it constitutes a principal part of the organs termed muscles, through the medium of which the various movements of the body are effected. Many of the muscles contain, besides flesh, a substance analogous to ligament, through the medium of which they are attached to the bones, and to which the term tendon is applied: muscles and tendons are composed of bundles of fibres, which may be unravelled to extreme minuteness; and when what appears to be a single fibre is viewed under the microscope, it resembles a chain of infinitely small globular The composition and properties of the blood, and the extraordinary changes which it suffers in its passage through the pulmonary vessels, are elsewhere defined. [BLOOD and RESPIRATION.] Without this exposure to the action of the air in the lungs, the blood is unfit for the support of life. We accordingly find that the heart is so constructed as to propel the blood which it receives through the structure of the lungs, and after it has there been aërated, to transmit it over the body: in fact, the heart is a hollow muscle: when it relaxes, its two principal cavities, or ventricles, are enlarged, and the blood flows in; when it contracts, they are diminished, and the blood is propelled into two large tubes or arteries, one leading to the lungs, and called the pulmonary artery, and the other to the system generally, and called the aorta: these arteries are not only elastic, but also muscular, so that they drive the blood onwards from the heart, its retrograde motion being effectually prevented by valves placed at their origin. The arteries are divided and subdivided into an infinite number of ramifications; and the branches from the same trunk are frequently observed to unite or anastomose in their course; so that when, by any accident, some are obstructed, an adequate supply of blood may be kept up by the others. As, however, the blood cannot return to the heart ANATOMY Different animals require different kinds and quantities of food; some living almost exclusively upon animal, others upon vegetable substances; hence their division into carnivorous and graminivorous tribes. Man partakes of both; and, accordingly, the structure of his digestive organs is intermediate between the comparative simplicity of the truly carnivorous, and the complexity of the graminivorous classes. In all the higher orders of animals, however, the mechanism of digestion is of a complicated character. by these vessels or arteries, we find that they they consist. Nothing, therefore, is stationary inosculate, or communicate at their extremities or permanent; and as the blood, on the one receives those which are removed: and with another series of tubes or vessels, which hand, conveys the materials required, so, on the are called veins. These are more numerous other, than the arteries, and generally accompany such as are useless, or would be hurtful if They have less mus- retained, are thrown off either by the intestines, them in their course. cular power; and as they are not assisted by the kidneys, the lungs, or the skin. It now the heart in propelling the blood, they open only remains to show how this waste is comto it larger and larger channels as it advances, pensated, and by what means those materials and are supplied with valves by which its which are thrown off in one form are replaced reflux is prevented. This is, in fact, the cir- in another. This leads us to the functions of culation of the blood (first made out by Harvey, another branch of the animal machinery, called as before mentioned); the veins ultimately the organs of digestion; those organs, namely, terminating in two large trunks, which pour the by which the food is converted into blood. blood into the right auricle of the heart, whence it is propelled into the right ventricle, from which arises the pulmonary artery, transmitting it through the lungs. From the lungs the blood (having been aërated) returns by the pulmonary vein into the left auricle of the heart, which contracting, propels it into the left ventricle, from which arises the aorta. Such then is the extraordinary mechanism by which the circulation of the blood is effected; but it must not be supposed that the whole of the blood is thus directly returned from the arterial into the venous system: a part of it is transmitted by minute arterial ramifications into the different structures and organs of which the body is composed, each of which is gifted with the power of assimilation, that is, of converting the blood, or a part of it, into a Some of these substance of its own kind. minute or capillary vessels also terminate upon the surface of the body, where they exhale perspirable matter; others, upon the membranes lining the cavities of the body, where they secrete the fluids which lubricate and moisten the interior surfaces; and others again go to the glands — those peculiar organs or structures, which have not only the power of separating certain parts of the blood, but of converting it into new forms, which are called secretions, some of which are ejected, others retained, for the purposes of the animal economy. Thus, then, it appears that the blood nourishes and preserves the body and all its parts, and that it is continually tending to the renovation and reproduction of the different organs; but this very process implies another, and no less extraordinary, function, which is performed by a distinct system; namely, that of absorption. There are, in short, a series of vessels which are continually carrying away the useless and worn-out materials; removing them in a state of solution; furnished, like the veins, with valves; terminating in a common trunk, called the thoracic duct; and pouring its contents into the veins, just before they enter the right auricle of the heart. It appears, therefore, that a continual system of deposition and removal is in action within the living body; that the ramifications of the arterial system are constantly renovating the different organs, whilst the absorbents are as constantly removing the materials of which 95 The first change which the food undergoes is in the mouth, where it is torn, ground, and The teeth are admirably moistened by machinery expressly adapted to those operations. contrived for this purpose; some of them cutting, and as it were mincing, others rubbing and grinding, whilst a fluid is supplied by the salivary glands so as to render the mixture of a proper consistency to be swallowed: this is effected by the organs of deglutition. The food is propelled from the mouth into the tube which conveys it to the stomach, and which is called the oesophagus; it is at the same time prevented, by an extraordinary and complicated arrangement of the parts concerned, from passing in any other direction, and more especially from entering the trachea or air-passage into the lungs. In the stomach the food is subjected to the secretions of that organ, called gastric juice, which is acid, and by which it is gradually converted into a greyish homogeneous semi-fluid substance, termed chyme: so that by the time the food has reached the right end of the stomach, or the pylorus, its original characters are entirely changed; its separate materials are no longer discernible, and it has acquired distinct properties; it is, in short, digested. How these changes are effected we know not, though many attempts have been made to explain them upon chemical and mechanical principles. Dr. Hunter, in his Introductory Lecture, has the following apposite remarks, in reference to this and similar phenomena: 'I must therefore expect,' he says, 'that you will not hereafter be surprised, when you find me avowing great ignorance in many of the most considerable questions relating to animal operations, such as sensation, motion, respiration, digestion, generation, &c. In my opinion, all these subjects are much less understood than most people think them. Our vanity deceives us, and persuades us that we ANATOMY have got the whole as soon as we have acquired a smattering of natural knowledge. Hence it is that the different sects of physiologists have endeavoured to explain animal functions upon such different principles. Hence, for example, to account for digestion, some have made the stomach a mill; some would have it to be a stewing-pot, and some a wort-trough; yet, all the while, one would have thought that it must have been very evident that the stomach was neither a mill, nor a stewing-pot, nor a worttrough, nor anything but a stomach. When the food has been thus far digested in the stomach, it passes into the duodenum, or upper end of the intestinal canal; a tube, the whole length of which is about six times that of the body, and which, therefore, is variously and strangely convoluted to enable it to be packed into the abdominal cavity. Into this portion of the intestines various vessels and glands deliver their secretions, partly for the purpose of lubricating its surface, and partly to assist in the further changes which are to be brought about in the chyme. Of these fluids, two are especially remarkable, from the importance and size of the glands by which they are secreted, and of the ducts by which they are conveyed; namely, the bile, which is of a green colour and bitter taste, and is secreted in the liver; and the pancreatic juice, which appears to resemble saliva, and which is secreted by a gland called the pancreas. The influence of these fluids upon the chyme is direct and important: the pancreatic secretion probably acts as a diluent merely; but the effect of the bile is more complicated; and it appears to be essential to the further change of the chyme into chyle, which is a white milk-like fluid, formed in the upper part of the intestine, and absorbed by a distinct set of vessels which, from the colour of their contents, have been called lacteals, and which convey the chyle, that is, the portion of the products of digestion fitted for nutrition, into the above-mentioned trunk of the lymphatics, whence it is transmitted into the veins, which open through the medium of the right auricle into the right ventricle of the heart. The bitter principle of the bile, and its colouring matter, are obviously not absorbed by the lacteals, but remain with the residue of the food, which is slowly propelled along the whole of the intestinal tube, and, having undergone certain changes in its passage, is ultimately voided as excrementitious. from the heart by the arteries, and conveyed back to it by the veins; how the useless and decayed parts are removed by the lymphatics; how the nutritious part of the food is carried into the blood by the lacteals; nd how venous is changed into arterial blood in the course of its passage through the pulmonary vessels; it only remains to observe, that the whole fabric is as it were protected from external injuries by its integuments. Of these the most exterior is a covering, varying in thickness and induration on different parts of the body, but everywhere without feeling, and called the epidermis ; immediately beneath it is a soft mucous substance termed rete mucosum; and under it the cutis, or true skin. These external coverings of the body are attached to and connected with the parts beneath, by cellular membrane. But though the animal owes much of its general security to these textures, it owes more to the senses, instincts, and appetites with which it is so miraculously endowed. By these it is led to pursue what is useful, and to guard against danger, inconvenience, and want. is this all; there has likewise been conferred, to a certain extent, upon all living bodies, the power of reproduction, by which they are frequently able to repair the slighter injuries to which the different organs are exposed; and if this power be exceedingly languid in the latter periods of old age, it is because the author of nature never intended that the animal structure should be immortal. He has fixed its bounds, which it cannot pass; and has measured out the time when the fairest fabric must crumble into dust, and its animating spirit return unto Him, the great Almighty Incomprehensible Being, who first bestowed it.'-Dr. Barclay's Introductory Lectures to a Course of Anatomy; and see Dr. William Hunter's Two Introductory Lectures, for details respecting the history, uses, and importance of the study of Anatomy. Nor ANATOMY, COMPARATIVE. So called because the organisation of the lower animals was first principally studied with immediate reference to that of the human subject. Galen, who visited the schools of Alexandria at a period when the dissection of the human body was no longer permitted, sought in the anatomy of the ape to acquire a vicarious knowledge of the anatomy of man. Vesalius, after the revival of literature, dissected various quadrupeds, and compared their organisation with that of man, in order to correct the errors of Galen, and to establish the true knowledge of the peculiarities of the human structure. Having now enumerated the various classes of organs in the human body, and adverted to their leading functions; having seen how the Succeeding anatomists have investigated the bones are united by articulations, and connec-structure of the lower animals, to acquire the ted by ligaments, flesh, and membranes, forming a variety of levers adapted to the motions of the limbs, and supporting and protecting the soft parts, as in the skull and spine; how the brain and nerves are concerned in the sentient energies, and in presiding over and directing muscular motion, and influencing the functions of the viscera; having likewise seen how each part of the body is nourished by the blood, which is sent knowledge necessary for experimenting upon them with success; and still more important discoveries in physiological science have result ed from tracing the modification and disappearance of different organs in the descending series of animals, as the only means by which we can obtain just notions of the uses and relative importance of the different organs in the animal economy, and a perception of the laws which ANATROPAL regulate their co-existence in the same individual. ANCHOR lifted or hung. the anchor When a hemp cable is used, the ring to which it is bent (fastened in a particular way) is covered first with tarred canvass, and then with pieces of rope secured firmly round it; this is When a chain cable is used, it called a puddening, and protects the hemp is shackled to the ring,, which is not then puddened. Aristotle, Harvey, and Hunter combined the investigation of the mature animals of different classes with observations of the different stages of developement of the embryo, and their example has been assiduously and successfully followed by the ablest comparative anatomists from the iron. of the present day, whereby some of the general laws of animal organisation, of developement, and of the analogies which apparently different parts bear to one another throughout the great scheme, have been discovered. A very important application of comparative anatomy is to the determination of the relative degrees of complexity in the organisation of different animals, and of the number and value of the points of resemblance which different species manifest to each other in the totality of their organisation. A study of the anatomy of animals, guided by these views, is essential to the determination of their natural affinities, which is the highest aim of the philosophic naturalist. Lastly, the labours of the comparative anatomist continually tend to bring to light examples of structures, designed with reference to especial purposes, of the most striking and forcible description; and thus provide for the moralist and divine a storehouse of facts peculiarly adapted to the illustration of the doctrine of final causes. [BIOLOGY; MORPHOLOGY; TELEOLOGY; DEVELOPEMENT.] Anatropal or Anatropous (Gr. ávarpéra, I invert). A very common kind of embryo, produced by one side of the ovule growing upon itself, while the other remains immovable, till at last that part of the ovule which was originally next the apex, is brought down to the hilum, the base of the nucleus in such cases being at the apex of the ovule. common apple, and the greater part of plants, offer examples of this. The Anauzite (Gr. ȧvaúžnτos, without augmentation). A mineral of a greenish-white colour, which occurs massive and granular at Bilin, in Bohemia. It is composed of silica, with much alumina, a little magnesia and protoxide of iron, and 11.5 per cent. of water. R & Anchor (Gr. &уKupa). Consists of a straight VOL. I. 97 Men of war and large ships carry two large bower anchors; and two others, of the same anchors of equal size, at the bows, called, thence, size, called the sheet and the spare anchors: besides two or three others, which are much smaller, for temporary occasions. The anchor, after being let go from the ship's bow or side, whether the shank be vertical or horizontal when it enters the water, arrives upright at the bottom, in consequence of the resistance of the water on the stock, when it falls over, and rests on the crown, one corner of a fluke, and the end of the stock. From this position of stable equilibrium on three points, forming a long narrow triangle, a small force disturbs it, when the stock, falling flat, one of the bills must pierce the ground, penetrating deeper as the cable pulls, until the arm is partly or entirely buried. Since the security of the vessel depends on the hold the anchor has of the ground, it is be such that the reaction of the soil against it, evident that the direction of the fluke should from the pull of the cable, may tend most effectually to keep it down. D B C A The pressure on the fluke being perpendicular to the surface, take A B to represent the pull of the cable, then the resolved portion of this perpendicular to the fluke is BC= AB cos. ABC; and the effect of this in keeping the fluke down is BD=BC cos..CBD BC sin. ABC, because AB is horizontal, and BD vertical, CBD is 90°-CBA; hence BD = AB sin. A B C cos. A B C, which is maximum when A B C=45°. The flukes of anchors in general make the angle with the shank much greater than this; but Lieut. Rodger, R.N., has, among other improvements, adopted this angle in his patent anchor, having established the above conclusion by experiment. Anchors are made of broad flat bars forged As the greatest strain upon the together. shank takes place during the act of weighing, the diameters of the shank are made unequal, the longest being placed vertical. This improvement is, we believe, due to Mr. Pering, on whose plan anchors have of late years chiefly been made. The weight of an anchor in men of war is estimated roughly at about 1 cwt. to a gun; in merchantmen, about 1 ewt. for each 15 tons. The weight of the anchor is not strictly proportional to the size of the vessel, as large vessels are Large anchors are thicker in less affected by sudden or violent motions than smaller ones are. H |