tant purpose: It is really surprising that they were ever dignified so much as to be classed with the great lateral ventricles. There is, therefore, in reality but one ventricle in each hemisphere; and even this is not strictly a cavity, as its upper and under surfaces are in contact. There is a

thin membrane which lines the surfaces and prevents them from adhering to each other, and which at the same time supports a complicated tissue of blood-vessels that nourish the interior of the brain.

The mouth of each ventricle is towards the median line, so that when, in consequence of disease, water collects in one cavity, it flows out into the other of the opposite hemissphere; until in some extreme cases, the whole brain becomes distended like a bladder-the convolutions upon the surface are unfolded-the skull bones separate, and all the coverings of the head give way and grow larger to make room for the increasing contents, until the head assumes nearly twice the usual size.

The under surface, or floor of the ventricle, assumes a form, irregular and winding, in some measure corresponding to the three lobes. This appearance has been denominated tri-cornes, or three horns, on account of the ventricle extending its windings in three directions, anterior, middle and posterior.

In the fore part of the bottom of the ventricle is the corpora striata, or striped body-an eminence resembling half a pear with its largest end in the front lobe and its opposite end pointing outward and backward.

The optic thalami is another eminence larger than the striata and situated just behind it. It receives its name from the erroneous supposition that it is the origin of the optic nerve. Spurzheim considered the striata and thalami as composed of fibres on their way and expanding to form at last the convolutions at the surface of the brain. The

situation of these parts, concealed from observation, renders their uses doubtful; the same is true of the fornix, a thin layer of medullary substance, that covers the thalami. There are also several other appearances, or parts in the ventricles which have received ridiculous and fanciful names, but nothing is known of their uses; such are the hippo-campus major and hippo-campus minor, &c.

SUBSTANCES OF THE BRAIN.

An examination of the surface of the brain shows it to be composed of a cineritious, or ashes colored substance, of a pulpy consistence, which seems to be almost entirely composed of a tissue of exceedingly minute blood vessels. If a cut is made so as to expose the internal substance of the brain it will appear of a cream color, or nearly white, and instead of being pulpy, like the cineritious substance, it is fibrous, and resembles in firmness and structure the nerves of the body. The cineritious substance is found in small quantities in the interior, but it is principally upon the outside, and surrounds the brain, as the bark surrounds a tree, and it has therefore been named the cortical or barklike substance.

The internal white fibrous substance is called the medullary substance.

It was the opinion of Spurzheim that the cortical substance was the nourisher of the medullary, but nothing is known with certainty on this subject.

CONVOLUTIONS OF THE BRAIN.

These are the folds, bounded by deep furrows, upon the external surface of the brain. It has been suggested that their use is to increase the surface of the brain without

adding to its bulk; and this seems a plausible conjecture. In the extreme cases of disease, to which I have alluded in speaking of the ventricles, the convolutions are spread out into a single sheet, just as the convolutions, or folds of an umbrella are spread out into a single sheet when it is opened; and this explains why persons whose heads are thus enlarged frequently manifest their mental powers with ordinary vigour; as the brain is merely unfolded, without its fibrous structure being destroyed.

Every convolution is not an independent and distinct phrenological organ, but in some instances several convolutions combine to constitute one organ, and in others a single convolution embraces an organ.

It is not therefore true, as some suppose, that each organ of mind may be separated from the rest of the brain by anatomical dissection. Anatomy shows the perfect agreement between the structure of the brain, so far as it is understood, and the organs of mind as they appear upon the surface of the skull. A skilful phrenological anatomist can readily point out the particular convolutions that go to constitute each organ; but no anatomist can trace the organs beneath the surface of the brain and show the boundary between them there. In the internal parts of the brain, the fibres of all the organs are blended and confounded together, so as to render it perfectly impossible to distinguish one organ from another. Anatomy affords no direct proof of the truth of phrenology. We study the structure of the brain to find an explanation of well established phrenological facts, and not to find evidence of their truth.

Phrenology was first dicovered, not by an examination or dissection of the brain, but by observing the agreement between the disposition of men and animals and the forms of their heads. The brain was afterwards examined, and its structure analyzed with great care, in the hope that it would

shed some new light upon the subject; but anatomy has hitherto been of little use to phrenology; on the contrary, we are indebted to phrenology for nearly all our useful knowledge concerning the anatomy of the brain.

So far as the anatomy of the brain is understood, it is in beautiful harmony with phrenology, but it is a great mistake to suppose that phrenology is dependent upon anatomy for evidence by which to establish its truth. Those opponents, therefore, who object to phrenology because it cannot be proved by dissection, evince an unpardonable ignorance of the subject. Most people cannot understand why so many physicians, who are supposed to know the nature of the brain disbelieve in phrenology; but the truth is, physicians are little wiser concerning the brain than other men; and even if they were ever so well acquainted with anatomy, they could not on that account, be able to judge concerning the truth of phrenology better than those who are entirely ignorant upon that subject. Any man who is capable of perceiving the forms and sizes which the head assumes in different individuals, and comparing their developements with their conduct, can judge concerning the truth of phrenology as well as the most eminent medical professor.

ARTERIES OF THE BRAIN.

All anatomists agree, that the amount of blood which the brain receives, is at least four times greater than that of any other part of the constitution of equal bulk. This astonishing fact, proclaims the great importance of the arterial system and organs of respiration to the operations of mind. The blood enters the brain by four different passages; two in front, called the right and left carotid arteries, and two in the back of the head, called the right and left vertebral arteries. It is curious to observe the contrivance which

prevents the blood from entering the delicate mass of the brain too suddenly and forcibly. Before the arteries are permitted to enter the skull, they are made to traverse several winding and almost retrograde passages, and encounter several obstructions, that serve to check the force of the current; the blood then enters the skull through four different arteries, that all unite at the base of the brain to form one great depot; which, although not exactly in the form of a circle, is denominated the circle of Willis; and it is from this circle that the blood finally takes its departure to enter the substance of the brain. Besides the arteries of the cerebellum, there are three principal arteries which go from the circle to the cerebrum; they are

The ANTERIOR,

The MIDDLE, and

The POSTERIOR,

so named from the three lobes of the brain which they supply; each of these arteries subdivide into an upper and under branch before they lose themselves in the brain.

VEINS, OR SINUSES OF THE BRAIN.

Although the blood enters the brain by four different channels, it is all returned through one great vein-the longitudinal sinus-which is situated in the median line between the hemispheres. It commences near the organ of Individuality, and follows the skull over to the lower part of Parentiveness; it then divides into two branches, one passing to the right, leaves the skull 'near Combativeness; the other passing to the left, leaves the skull in a similar manner. The course of this great sinus may be traced on the inner surface of the skull by the deep impression it makes in the bone, particularly at the back part, where it