the dura mater, the falciform (scythe-like) process of the dura mater. From its dipping down between the two halves of the brain, the chief purpose of this membrane seems to be to relieve the one side from the pressure of the other, when we are asleep, for example, or have the head reclining to either side. The membrane does not descend to the bottom of the brain, except in a small part, at the front and back, G G in Fig. 2. It descends about twothirds of the depth of the whole brain. At the point where it terminates, a mass of fibres, named the corpus callosum, passes between and connects the two hemispheres. The convolutions represented in Fig. 1. belong chiefly to the coronal region, and manifest the moral sentiments.'

The cut Fig. 2. represents the convolutions lying at the base of the brain.

Each half or hemisphere of the brain is, in its turn, divided, but in a less marked way, as the divisions are observable only on its inferior surface,-into three portions, called, from their situations, the anterior, middle,

and posterior lobes, each occupying nearly a third of the whole length of the brain. The anterior lobe, being the portion lying before the dotted line E E, occupies the forehead; the middle is all the portion lying between the two transverse lines E E and F F, above and a little in front of the ears; and the posterior lobe is that portion lying behind the transverse line F F, and corresponding to the back part of the head.

'Beneath the posterior lobe, a strong fold of the dura mater, called the tentorium, is extended horizontally to support and separate it from the cerebellum A A, or little brain, lying below it. The cerebellum forms the last great division of the contents of the skull. Its surface is marked by convolutions, differing, however, in size and appearance from those observed in the brain.

Adhering to the surface of the convolutions, and consequently dipping down into, and lining the sulci or furrows between them, another membrane, of a finer texture,

and greater vascularity, called pia mater, is found. The blood vessels going to the brain branch out so extensively on the pia mater, that, when a little inflamed, it seems to constitute a perfect vascular net-work. This minute subdivision is of use in preventing the blood from being impelled with too great force against the delicate tissue of the brain.

'A third covering, called the arachnoid membrane, from its fineness resembling that of a spider's web, is interposed between the other two, and is frequently the seat of disease.

'On examining the convolutions in different brains, they are found to vary a good deal in size, depth, and general appearance. In the various regions of the same brain they are also different, but preserve the same general aspect. Thus they are always small and numerous in the anterior lobe, larger and deeper in the middle, and still larger in the posterior lobe. The thick cord or root C, springing from the base of the brain, is named the medulla oblongata, or oblong portion of the spinal marrow, which is continued downwards, and fills the cavity of the spine or back-bone. At one time the brain has been regarded as proceeding from, and at another as giving rise to, the spinal marrow; but, in reality, the two are merely connected, and neither grows from the other. The false analogy of a stem growing from a root has led to this abuse of language.

The small round filaments or cords seen to proceed from the sides of the medulla oblongata, and from near the base of the brain, are various nerves of sensation and motion, some of them going to the organs of sense, and others to the skin and muscles of the face, head, and other more

distant parts. The long flat-looking nerve a a, lying on the surface of the anterior lobe, is the olfactory, or nerve of smell, going to the nose. The round thick nerve 4 4, near the roots of the former, is the optic, or nerve of vision, going to the eye. That marked b is the motor nerve.

which supplies the muscles of the eyeball. A little farther back, the fifth pair c, is seen to issue apparently from the arch D, called Pons Varoli, or bridge of Varolius. It is a large compound nerve, and divides into three branches, which are ramified on almost all the parts connected with the head and face, and the upper and under jaw. It is a nerve of both sensation and motion, and one branch of it ramified on the tongue is the nerve of taste. Other branches supply and give sensibility to the teeth, glands, and skin. The seventh or auditory nerve e, is distributed on the internal ear, and serves for hearing. The eighth, or pneumogastric nerve d, sends filaments to the windpipe, lungs, heart, and stomach, and is one of great importance in the production of the voice and respiration. It also influences the action of the heart, and the process of digestion.

'Such are the principal nerves more immediately connected with the brain, but which it is impossible to describe more minutely here. Those which supply the trunk of the body and the extremities, issue chiefly from the spinal marrow; but they also must, for the present, be passed over in silence, that we may return to the consideration of the brain.

The brain receives an unusually large supply of blood, in comparison with the rest of the body; but the nature of its circulation, although a very interesting subject of study, being only indirectly connected with our present purpose, cannot now be discussed.'

The brain is the fountain of nervous energy to the whole body, and many individuals are habitual invalids, without actually laboring under any ordinary recognised disease, solely from defective or irregular exercise of the nervous system. In such cases, not only the mind, in its feelings and intellectual capacities, suffers debility, but all the functions of the body participate in its langour, because all of them receive a diminished and vitiated supply of the nervous stimulus, a due share of which is essential to their

healthy action. The best mode of increasing the strength and energy of any organ and function, is to exercise them regularly and judiciously, according to the laws of their constitution.* The brain is the organ of the mind; different parts of it manifest distinct faculties; and the power of manifestation in regard to each is proportionate, cæteris paribus, to the size and activity of the organ. The brain partakes of the general qualities of the organized system, and is strengthened by the same means as the other organs. When the muscles are called into vivacious activity, an increased influx of blood and nervous stimulus takes place in them, and their vessels and fibres become at once larger, firmer, and more susceptible of action. Thought and feeling are to the brain what bodily exercise is to the muscles; they put it into activity, and cause increased action in its blood vessels, and an augmented elaboration of nervous energy. In a case reported by Dr. Pierquin, observed by him in one of the hospitals of Montpelier in 1821, he saw, in a female patient part of whose skull had been removed, the brain motionless and lying within the cranium when she was in a dreamless sleep; in motion and protruding without the skull when she was agitated by dreams; more protruded in dreams reported by herself to be vivid; and still more so when perfectly awake, and especially if engaged in active thought or sprightly conversation. Similar cases are reported by Sir Astley Cooper and Professor Blumenbach.†

Those parts of the brain which manifest the feelings, constitute by far the largest portion of it, and they are best exercised by discharging the active duties of life and of religion, the parts which manifest the intellect are smaller, and are exercised by the application of the understanding in practical business, and in the arts, sciences, or literature.

* See Dr. A. Combe's Physiology, &c., 3d edit., pp. 147, 192, 277. + See American Annals of Phrenology, No. I. p. 37. Sir A. Cooper's Lectures on Surgery, by Tyrrel, vol. i. p. 279. Elliotson's Blumenbach, 4th edition, p. 283. Phren. Journ. vol. ix. p. 223.