the brain, and presents both cineritious and medullary substances; but it differs from it in form and internal arrangement. In fig. 3, p. 75, it is seen partly in section (between S and 48) and partly with its natural external appearance (1.) The cerebellum is separated from the brain by a strong membrane called the tentorium: in animals which leap, as the cat and tiger, the separation is produced by a thin plate of bone.* Its fibres, however, originate in that part of the medulla oblongata called the corpora restiformia, from which also the organs of several propensities arise; so that the brain and cerebellum, although separated by the tentorium, are both connected with the medulla oblongata, and through it with each other.

The MEDULLA OBLONGATA is sometimes spoken of as one of the three great divisions of the brain. It is, in fact, the part from which the fibrous matter of the brain and cerebellum proceeds; and it forms, as it were, the capital of the column of the spinal marrow.

OF THE INTEGUMENTS OF THE BRAIN.

THE brain is formed before the bones which invest it. The ossification

of the skull is a gradual process. The brain already formed is invested with strong membranes, and between the coats of the outer membrane the ossification commences, which process is not completed until the ninth year. During life the brain is embraced in its whole peripheral extent by a very thin transparent and delicate membrane called the pia mater, which sinks down into its furrows, and serves to convey the blood vessels to its different parts. Immediately above the pia mater are two layers of a still thinner membrane, resembling in its tenuity a spider's web, and thence named the tunica arachnoidea. It covers the surface of the brain uniformly, without passing into its folds. A fluid secretion takes place from the opposed surfaces of this membrane, by which they are lubricated and prevented from adhering to each other. The dura mater is a thin, but strong, opaque membrane, lining and strongly adhering to the inner surface of the skull, and which embraces the outer surface of the brain above the membrane last-mentioned. When in health it does not possess sensibility, and has been pricked without causing pain. The brain, enclosed in these membranes, fills exactly the interior of the skull; so that a cast, in plaster, of the interior of the skull is a fac simile of the brain, covered by the dura mater. Between the two layers of the arachnoid membrane a very small quantity of fluid is said to exist, but not exceeding a line in thickness. This fluid does not, in any degree that can be distinguished by the hand or eye, cause the form of the interior of the skull to differ from the form of the exterior of the brain.

The skull is not an adamantine barrier, confining the brain within specific boundaries; but a strong, yet changeable, covering, shielding it, and accommodating itself to its size while in the progress of its growth. At birth it is small; it increases as the brain increases, and alters its shape with every change of the cerebral form; it stops in developement when the brain has attained its full size, and diminishes when the size of the brain suffers diminution, as happens in old age or disease. A process of ab* Richerand conceives the purpose of this arrangement to be the prevention of cerebral concussion in leaping: but Dr. Vimont objects to this view, on the ground that many animals accustomed to take great leaps, such as the squirrel and monkey, have not an osseous tentorium; while, on the other hand, a bony plate occurs in some animals whose movements are slow and heavy, such as the badger. Vimont's Treatise on Human and Comparative Phrenology, i., 63.

On the admirable fitness of the skull to protect the brain, see The Phrenological Journal, viii., 332.

+ Cases of diminution of the skull will be found in The Phrenological Journal, ix., 468–470.

sorption and deposition goes continually on in its substance; so that, if the brain presses from within, the renovating particles arrange themselves according to this pressure, and thus the figure of the skull and of the brain in general correspond. In cases of water in the head, the skull sometimes extends itself, by this process, to an enormous size.

The skull is composed of nine bones. These are two frontal bones, which compose the forehead, and generally soon unite into one, though in some adults they continue double; two parietal bones, forming the greater part of the upper and lateral regions of the skull; two temporal, around the ears; one sphenoid, in the anterior part of the basilar region; one occipital, in the back and under part of the skull, immediately above the neck; and one ethmoidal, at the base behind the nose. The lines of junction of these bones are termed sutures, and form, in most parts, a sort of dovetailing. The principal sutures are the sagittal, separating the two parietal bones at the middle of the top of the head; the coronal, which divides the frontal from the parietal bones; the lambdoidal, between the occipital bone and the two parietals, and deriving its name from its resemblance to the Greek letter lambda (A); the frontal, dividing the two frontal bones when they are not conjoined; and the temporal, named also the squamous, from its scaly appearance, dividing the temporal bones from the parietal, and to some extent from the sphenoid and occipital.

The annexed figure represents a skull with the two sides cut away, down nearly to the level of the eyebrow, leaving a narrow ridge in the

middle of the top standing. AAA is the edge of the skull, resembling an arch. It is here represented thicker than it is in nature, in order to show the diploë. Most parts of the skull consist of two plates, called the outer and inner tables, having between them a spongy C substance, like cells in a marrow-bone, called the diploë. The substance hanging down from the arch of the skull, having delicate lines traced on it, like the sap vessels in leaves, is the memrane which separates the two halves of the brain. It is a continuation of the dura mater, and is called the falciform process, from its resemblance to a scythe. It is well supplied with bloodvessels; and a large portion of the blood returning from the brain to the heart, goes up these vessels into a canal formed by the membrane all along the line of its attachment to the skull. The course of the blood through the canal is from the front backward, and then downward. The two hemispheres of the brain are completely separated, as far as this membrane is seen to extend downward in the cut. At the lower edge of it an open space appears: the commissure, or collection of fibres which unite the two sides, named the corpus callosum, goes through that space. The cerebellum lies at B C,

in a part of the skull not opened. The membrane, on reaching the point C, spreads out to the right and left, and runs forward, so as to separate the cerebellum from the brain; the latter lying above, and the former below it. B is the mastoid process, or bone to which the sterno-mastoid muscle is attached. It lies immediately behind the opening of the ear, and is not connected with the brain.

As the diploë, except in the parts mentioned below, is almost equally thick, it follows that the two tables of the skull are nearly parallel to each other. This is seen in the section represented in fig. 3, p. 75.* The internal, indeed, bears some slight impressions of blood vessels, glands, &c., which do not appear externally; but these are so small as not to interfere with phrenological observations. The departure from perfect parallelism, *See Dr. Caldwell on the parallelism of the tables, Phren. Journ., ix., 222

A. Basilar or Sphenoid Bone. Small portion reaching the surface at the side.

B. Temporal Bone.

C. Occipital Bone.

D. Parietal Bone.

E. Frontal Bone.

M. Meatus Auditorius Externus, or external opening of the ear.

P. Mastoid process of the Temporal Bone, which serves to give attachment to

the Sterno-mastoid muscle.

SS. Sutures, or serrated edges by which the different bones are joined together.

+i

where it occurs, is limited to a line, one-tenth or one-eighth of an inch, according to the age and health of the individual. The difference in developement between a large and a small organ of the propensities and soine of the sentiments amounts to an inch and upward; and to a quarter of an inch in the organs of intellect, which are naturally smaller than the others.* The squamous portion of the temporal bones is much thinner than the other parts of the skull. But as this is the case in all heads indiscriminately, it is not a source of error to the phrenologist. Every skull, moreover, is thick at the ridges of the frontal bone and the transverse ridge of the occipital, (48, fig. 3, p. 75,) and very thin at the super-orbitar plates of the frontal bone, forming the roof of the sockets of the eyes-and also in the middle of the occipital fossæ. Dr. Gall states that sometimes the skulls of very stupid people are unusually thick ;t and Dr. Vimont has frequently observed the same thing to occur in persons of an athletic constitution. In savages the skull is often thick.

The integuments which cover the skull on the outside, indisputably lie close upon its surface, and are so uniform in their thickness as to exhibit, with sufficient accuracy, its true figure. The temples and occiput are the only parts where the integuments are thicker than at the others, and the phrenologist attends to this fact in making his observations. Thus there is no obstacle in general to the discovery of the figure of the brain, by observations on the form of the skull or head.

This doctrine has been frequently disputed by opponents of Phrenology; but many anatomists have taught it. Magendie, in his Compendium of Physiology, says, that "the only way of estimating the volume of the brain in a living person is, to measure the dimensions of the skull; every other means, even that proposed by Camper, is uncertain."§

Sir Charles Bell also observes, "that the bones of the head are moulded to the brain, and the peculiar shapes of the bones of the head are determined by the original peculiarity in the shape of the brain." Dr. Gordon likewise, in the 49th number of The Edinburgh Review, has the following words: "But we will acquiesce implicitly for the present in the proposition, (familiar to physiologists long before the age of Gall and Spurzheim,) that there is, in most instances, a general correspondence between the size of the cranium and the quantity of cerebrum; that large heads usually contain large brains, and small heads small brains."-(P. 246.) There are, however, cases in which it is not possible to discover the form of the brain by examining the skull. These are instances of disease and old age. In disease the skull may be enlarged or diminished in volume by other causes than changes of the brain; and in old age the inner table of the skull sometimes sinks, while the outer table preserves its original size in such cases the true developement of the brain cannot be accurately inferred from the appearances of the head.**

* "Jamais je n' al prétendu distinguer des modifications peu prononcées des formes du crâne, ou de légères nuances du caractère."-Gall, iii., 41. + Tome iii., p. 43. ‡ Vol. i., p. 285.

Milligan's Translation, p. 104.

Bell's Anatomy, ii., 390. Sir C. Bell adds, in a foot-note, "Certainly the skull is adapted to the form of the brain; but there is a deeper question, which our craniologists have forgotten-Is the brain constituted in shape with a reference to the future form of the head?" It is difficult to see the importance of this question. Not only is the skull, at every period before the decline of life, adapted to the form of the brain, but it increases in size when the brain enlarges, and decreases when the brain diminishes. The reader will find an answer to Sir Charles Bell's objections in The Phrenological Journal, viii., 333.

**According to Dr. Gall, the skulls of aged people are generally thicker, lighter, and more spongy than those of young men and adults: but Dr. Vi