BLOOD. THORACIC DUCT.-ABDOMEN.

intimate union of the same materials produces most powerful agents, namely, the nitrous and the nitric acids.

The BLOOD is a red fluid of a saltish taste, of a somewhat urinous smell, and glutinous consistence, which circulates in the heart, arteries, and veins, conveying nutrition, heat, and excitement to the whole body. The quantity of blood in the human body is estimated to be about twenty-eight pounds in an adult. Of this, four parts are contained in the veins, and a fifth in the arteries. The blood being returned by the veins of a dark red color to the heart, it is sent from that viscus into the lungs, to undergo some material change by coming in contact with atmospheric air in the air-cells of the lungs: after which, as has been stated, it is returned to the heart again of a much more florid color, and then impelled into the arteries, to be distributed over the body. The heat of the blood is usually about 98 degrees.

THORACIC DUCT, an important vessel called the trunk of the absorbents. It is of a serpentine form, and about the diameter of a crowquill. It is attached to the bones of the back, and extends from the lower opening of the midriff or diaprahgm (a membrane which separates the heart and lungs from the stomach, bowels, and other abdominal viscera,) to the angle formed by the union of the left subclavian and jugular veins, into which it opens and evacuates its contents, there to be mixed with the blood. These contents consist chiefly of chyle, a whitish or milky fluid, separated from the food by the process of digestion, and taken up by the absorbents thickly spread over the intestines, and by them conveyed to the thoracic duct.

Such are the offices of respiration and the blood. We shall now proceed to consider some of the most important of the abdominal viscera.

The ABDOMEN consists of all that portion of the trunk of the human body situated below the thorax. It contains the liver, its gallbladder, the stomach, the spleen, the pancreas, the intestines, the mesentery, the kidneys, the urinary bladder, the omentum, &c. It has also numerous blood vessels, nerves, and absorbents.

The LIVER, which is the largest and most ponderous viscus in the abdomen, it weighing, in adults, about three pounds, is of a deep red color. It consists of a glandulous mass, interspersed with numerous blood vessels. It is situated under the diaphragm, inclining to the right side of the body, having the stomach beneath it; between which and the liver itself, lies the gall-bladder, with which it is of course intimately connected. It is divided into two principal lobes, the right of which is by far the largest. Its shape approaches that of a circle; it is attached to the diaphragm by the suspensary and other ligaments. It is larger in young animals than in old ones.

The BILE is of a yellow-green color, about the consistence of thin oil; when much agitated it froths like soap and water. Its smell is somewhat like musk; its taste is bitter. It is, in fact, a species of soap; and like other soap, is successfully employed to remove grease from clothes, &c. The gall-bladder in the human body is shaped like a pear, and is generally capable of containing about an ounce. It is firmly connected to the liver. In the elephant, stag, all insects and worms, this

SPLEEN. STOMACH.-DIGESTION.

reservoir is wanting, the bile which they secrete, passing at once into the intestinal canal. The real use of the bile does not even now seem to be accurately ascertained. It appears, however, to assist in separating the chyle from the chyme, to excite the intestines to action, and to produce the healthy appearance of the intestine evacuations.

The SPLEEN, or MILT, is a spongy viscus of a livid color, in form somewhat resembling a tongue, but its shape, situation and size vary very much. It is, in a healthy subject, always on the left side between the false ribs and the stomach. Its general length is six inches, breadth three, and one thick. It is connected, by the blood vessels, to the stomach and the left kidney. It is larger when the stomach is empty, and smaller when compressed or evacuated by a full stomach. The uses of the spleen have, till lately, been considered as unknown; but by a paper of Sir E. HOME, in the Philosophical Transactions, it appears probable that this viscus is a reservoir for the superabundant serum, lymph, globules, soluble mucus, and coloring matter carried into the circulation immediately after digestion is completed.

The STOMACH is a large receptacle, varying in its capacity from about five to eleven pints. It is situated under the left side of the diaphragm, its left side touching the spleen, and its right covered by the thin edge of the liver; its figure nearly resembling the pouch of a bag pipe, its left end being most capacious. The upper side is concave, the lower is convex. It has two orifices, both on its upper part; the left, through which the aliment passes from the mouth through the gullet or @sophagus to the stomach, is named cardia; the right, through which it is conveyed out of the stomach into the duodenum, is named pylorus, where there is a circular valve which hinders the return of the aliment from the gut, but does not at all times hinder the bile from flowing into the stomach. The stomach, like the intestinal canal, is composed of three coats or membranes.

The uses of the stomach are to excite hunger, and, partly, thirst; to receive the food from the œsophagus, and to retain it, till, by the motion of the stomach and the admixture of various fluids, and by many other changes not exactly understood, it is rendered fit to pass the right orifice of the stomach, and afford chyle to the intestines for the nutrition of the body; or, in other words, till the important process

Of DIGESTION is completed. The chief agent in this process is, beyond question, the gastric juice; a fluid that is secreted from certain glands in the stomach, and which possesses great solvent powers in regard to numerous animal and vegetable substances. The food being duly masticated, and blended with a considerable portion of saliva, is propelled into the stomach, where it soon undergoes a remarkable change, being converted into a pulpy mass, termed chyme; the chyme afterwards passes from the stomach into the small intestines; here, it is mixed with bile, and separated into two portions, one of which is as white as milk, and called chyle; the other passes on to the larger intestines, and is voided as excrementitious matter. The chyle is absorbed by the lacteals, which terminate in the trunk or tube called thoracic duct; it is there mixed with variable proportions of lymph, and, lastly, with the blood, as stated under that article.

GASTRIC JUICE.-PANCREAS.-INTESTINES.-KIDNEYS.

The GASTRIC JUICE is said to be of so powerful a nature, that after death the stomach is occasionally eaten into holes by its action. And it is also said, that if exposed to a proper temperature, it will digest food in metal tubes.

The PANCREAS, or SWEET-BREAD, is a large gland of the salivary kind, of a long figure, compared to a dog's tongue. It lies across the upper and back part of the abdomen, under the stomach. Its use is to secrete a juice called the pancreatic juice, which appears to be similar in its properties to saliva, and together with the bile helps to complete the digestion of the aliment. It communicates with the duodenum.

The INTESTINES consist of that convoluted tube beginning at the right orifice of the stomach called pylorus, and ending with the sphincterrecti. The length of this canal is generally six times the length of the whole human subject. It is divided by nature into two parts. The small intestines begin from the stomach, and fill the middle or fore part of the abdomen; the large intestines occupy the sides, and both the upper and lower parts of the same cavity.

The KIDNEYS are shaped like a kidney-bean. They are situated on the lower part of the back, one on each side. They are generally surrounded with more or less fat.

The SENSES are those faculties or powers by which external objects are perceived. The sight, touch or feeling, hearing, smell and taste, are called the senses. The organs through which they operate are the following:

The EYE is the organ of seeing. The eye-lids, the eye-lashes, and the eye brows, require no particular description. The eye-ball is of a globular figure; it is composed of various membranes; but those parts of the eye deserving the most notice, are the iris, the pupil, and the retina. The iris is that colored circular ring situated beneath the crystalline lens, which surrounds the central or dark part called the pupil. It is capable of expanding or contracting, which it constantly does, according to the quantity of light which is thrown upon the eye. In a very bright light the pupil is reduced by the contraction of the iris to a very narrow hole; in a dark place the pupil is so much enlarged, as to render the iris scarcely visible. The pupil is the dark round opening in the middle of the eye, surrounded by the iris, and through which the rays of light pass to the retina, which is the true organ of vision, and is formed by an expansion of the pulp of the optic nerve. Externally the globe of the eye and the transparent cornea are moistened by a fluid called the tears, which are secreted in the lachrymal glands, one of which is situated above each inner corner of the eye. In proportion as the eye is more or less round, is the sight of a person longer or shorter. Persons of short sight are called myopes, of long sight, presbyopes.

TOUCH, or FEELING, resides in every part of the body that is supplied with nerves. The sense of touch is most exquisite in the lips, the tops of the fingers, the tongue, and a few other places.

The EAR is the organ of hearing. In man it consists of an external ear, or auricula, and an internal bony cavity with numerous circular and winding passages, by which the vibrations of the air are collected

NOSE. TASTE.-SEXES.

and concentrated, and by a peculiar mechanism conveyed to the auditory nerves. The ear is supplied with peculiar glands, which secrete an unctuous substance, called the wax of the ear. The external auditory passage proceeds in a spiral direction to the tympanum or drum of the ear, which forms a complete partition between this passage and the internal cavities. Beyond the tympanum is a hemispherical cavity which leads to the fauces, or opening at the back of the mouth: this opening is of a trumpet form. The inner cavity, including the winding passage, is aptly called the labyrinth of the ear. The sense of hearing is perhaps still more important than that of seeing; but as we can have no just conception of the real state of social existence without either of these senses, it is idle to speculate on such comparisons.

The NOSE is in man, and most of the superior animals, the organ of smelling. The structure of the nose has nothing in it so very peculiar that can convey any idea of a mechanical organization to aid the sense of smelling. It is true, the nerves of the nose are considerably expanded over the nostrils, and are defended from external injuries by a peculiar mucus; but it is very difficult to ascertain what are the essential organs of smelling. The nostrils are two passages of the nose which communicate interiorly with the upper part of the mouth. The use of the nostrils is for smelling, respiration, and speech. The nose is an important part of the human countenance; it is considered in almost all countries as one of the features to which peculiar merit is attached.

The TASTE resides chiefly in the tongue, in conjunction with the palate, lips, and other parts of the mouth. The tongue is however destined to perform much more varied and important functions than that of conveying to the mind the taste of sapid bodies. It is the tongue, in conjunction with the lips, teeth, palate, and throat, which produces the sounds of language. The tongue is partly muscular, and partly composed of membranes and cellular substance. Its upper side is covered with papille, in which the taste more immediately resides. The impression of sapid bodies on the organs of taste is modified by age, size, habit, and the more or less frequent application of strong stimulants. The state of the stomach, as well as general health, is often indicated by the state and color of the tongue. In health the tongue is always of a red color; in disease it varies from white to yellow, and sometimes is almost black. In health the tongue is always more or less moist; in disease frequently parched and dry; this last condition is, however, produced in health by the mere absence of moisture, evinced by the sensation we call thirst.

The SEXES differ by obvious indications; but there are some not so universally recognized, which we may mention. The male is generally of a larger size than the female, and more robust; the male becomes frequently bald on the top of the head, the female rarely or never; the male has always more or less beard, the female rarely any, except as old age approaches, and then it is chiefly confined to the upper lip. The anatomical differences, besides the obvious ones, are, in the female, a larger pelvis than in the male, more delicate muscles and smaller bones; and the phrenologists say, that the female skull is more elongated than the male, from the protuberance in the middle of the

MIND.-SENSATION.

back part of the skull, (which they denominate philoprogenitiveness, or love of children,) being more prominent. The mental differences of the two sexes are also important; women appear to possess more imagination and less judgment than men; these differences are unfortunately too often widened by mistakes in the education of the female mind.

SECTION II.

ON THE MIND AND ITS FACULTIES.

The term MIND has been lately applied by philosophers to the intellectual portion of man, as being a more correct term than either soul or understanding. It implies that part of our being which is occupied in thought. The seat of the mind is manifestly the brain: but in what part of it, whether the whole, or in the pineal gland, as Des Cartes maintains, where he says all the nerves terminate; or whether, as Soemmering states, the fluid contained in the ventricles of the brain be its seat, is unknown: all such opinions being mere conjectures.

The mind, or soul, has been usually divided into a certain number of faculties. We shall consider it from its more simple to its more complex state. The commonest and simplest impression made upon the mind being conveyed to it by either of the senses, is called

SENSATION. Sensation is either pleasurable or painful; in proportion to the degree of pleasure or of pain produced by a sensation, will be the vividness of its apprehension by the mind. An apprehended sensation is termed PERCEPTION: that is, when the mind itself perceives, recognizes the sensation,-when it becomes the subject of thought in the mind, it is then called perception. An IDEA is a resemblance or image of any thing, which, though not seen, is conceived,— apprehended by the mind;-an idea appears to be, therefore, nothing more than a well-defined and apprehended perception. An idea may be simple or complex, true or false. Simple ideas are those which arise in the mind from sensation; as those of color by the eye, of sounds by the ear, heat by the touch, &c.; some ideas are formed by sensation and reflection jointly, as pleasure, pain, power, existence. Complex ideas are infinite; some are not supposed to exist by themselves, but are considered as dependencies on, or affections of substantives, as, triangle, gratitude, murder, &c. Combinations of simple ideas are such as, a dozen, a score, beauty, theft, &c. The association of ideas, and consequently of affections, is one of the most important characters of the human mind, and the great source of our happiness or misery.

In tracing the process of the human mind in acquiring knowledge, we observe the following curious analogies or gradations; it commences with a simple idea or thought impressed, which is connected with simple perception. This solicits attention, which, according to its degrees of importance, disposes to observation, consideration, investiga