organ, (all other things being equal) is in exact proportion to its size. Upon this principle, practical phrenology depends. It is a demonstrable truth, in regard to all the material world, that two or more substances of the same quality and form, will possess a degree of strength and power proportionate to their size; and it is surprising that any individual of common intelligence, should be found in the present age to controvert so obvious a proposition. A fourth principle is, that the size and activity of the organs may be affected by temperament, disease, exercise and education. CHAPTER IV. ANATOMY OF THE BRAIN. THIS has always been a subject of much learned discussion; but until the time of Dr. Gall, the little that was known concerning it, was of no material use, and only tended to distract the minds of those medical students who endeavored to understand it. The different parts of the brain, instead of receiving names expressive of the functions which they performed, have been named according to the shape which they generally assume. This accounts for the strange and unphilosophical terms which are used by writers on anatomy, and which are calculated only to discourage the common student. Indeed, few medical students think it worth their trouble to learn the details of the anatomy of the brain as it is commonly taught, since they soon ascertain that it is of no use; consisting merely in learning the locality of parts, the offices of which are unknown and even unconjectured, and observing their resemblance in form to certain familiar objects from which they derive their names, such as olive-shaped, harrow-shaped, funnel-shaped, &c. The discovery of phrenology threw much light on the anatomy and physiology of the brain, and enabled scientific men to give names to many parts expressive of their functions. HEMISPHERES OF THE BRAIN. The brain and spinal cord is in two equal and symmetrical halves called hemispheres, one of which is contained within the right side of the skull and vertebra, and the other within the left. Every essential part that is found upon one hemisphere is found in a corresponding place upon the opposite:thus, upon one hemisphere phrenologists have discovered thirty-six organs of mind, and a corresponding number of similar organs upon the other side: thus also, upwards of forty nerves proceed from one hemisphere of the brain and spinal cord to different parts of the body, and an equal number proceed from the other hemisphere in a similar manner. This explains why nervous diseases sometimes affect one side of the face or body and not the other. The division of the great organ of mind into hemispheres corresponds with the fact that all the organs of the body that obey the mind are double, so also are the organs of sense that carry information to the mind. Thus we have two hands and two feet, two eyes, &c. The body, and particularly the face, may therefore be said to be divided into right and left hemispheres, and this is a good illustration of the manner in which the brain is divided. The line which divides the right from the left hemisphere is called the mesial, or median line. COMMISSURES OF THE BRAIN. These are parts that extend across from one hemisphere of the brain to the other, and are evidently intended to produce a unity of action between them; so that although the great organ of mind is double, the operations of mind are single; and notwithstanding the organs of sense are double, the sensations are single; one side of the head cannot be angry while the other is pleased; one side cannot delight in music while the other is averse to it; but both hemispheres act together as if they were one, which could not possibly be the case if they were not intimately united by means of the commissures. The largest commissure is called the corpus callosum ; this may easily be seen by separating with the fingers the two hemispheres of the uncovered brain; a white mass several inches wide and about half an inch in thickness will then be seen extending across from one hemisphere to the other, like a bridge. The annular protuberance is about one sixth the size of the corpus callosum, and extends from one hemisphere of the cerebellum, or organ of amativeness, to the other, passing across the medulla oblongata, in such a manner as to be sometimes called the bridge of Varolius, or pons varoli. We can only conjecture the use of these two commissures from their situation; the fact, however, that they are not found in some classes of animals, seems to indicate that they are not so important as their size would lead us to suppose. Dr. Spurzheim also mentions two cases where the corpus callosum was rent entirely assunder, and yet the individuals continued to manifest their minds as usual. But there are still three others to be seen at the base of the brain by which Dr. Spurzheim considered the true commissures. They are The ANTERIOR, The POSTERIor, each of which is about equal in size to a goose quill, and they cross, (as their names indicate,) one in the front, another in the middle, and the third in the back part of the brain. Besides these commissures there is in the front part of." the medulla oblongata, a decussation; that is, the fibres cross from one side to the other in such a manner as to resemble plaited straw-the hemispheres being entirely separated from each other by a membrane, except where the commissures cross. There are several parts seen in the median line which do not seem to belong to either hemisphere, and the uses of which are unknown. One of these is called the pineal gland, and is about the size of a pea; this is celebrated as the part where Descartes fancied the soul to reside, and is situated just above the posterior commissure, and seems to be attached to it. Just above the same place are four other small round bodies, known by the name of the quadrigeminal bodies. There may be seen also in the median line at the base of the brain, near where the optic nerves unite, two little round bodies, which on account of their supposed resemblance to breasts, are called mamillary bodies; and near |