ON THE STRUCTURE
AND
ANATOMY OF THE BRAIN.
The BRAIN is admitted by physiologists, to be the organ of the mind, although dissection furnishes no clue to its functions, but the same may be said of the eye, the tongue or the ear. The phrenologist compares developement of brain with manifestation of mental power, and by its classification of organs arranges those instruments through which the mind manifests its power during life. A brief description of the brain therefore will be advantageous. It is a mass of soft matter not homogeneous, but presenting different appearances; part of it white in colour, and fibrous in texture is named the medullary substance and abounds in the interior; the other matter is of a grey colour and not fibrous in appearance, this forms the outer-portion of brain, they do not blend together, but have a perfect line of distinction. There is no adipose or fatty matter in the skull. The brain is divided into two hemispheres, separated by a strong membrane termed the Falciform process of the Dura Mater, and each hemisphere is divided into three lobes, anterior, middle and posterior: the two hemispheres and the organs of each side are brought into communication by fibres running transversely. The cerebellum and brain are only slightly and indirectly connected.
The greater portion of the brain is destitute of sensibility, Sir C. Bell imagines from this that it possesses a higher office than that of sensual perception. The external substance of the brain is arranged in convolutions or folds; these appear to be intended for the purpose of increasing its superficial extent with the least enlargement of size,—in the inferior classes of animals there are no convolutions, but they increase in number and extent as we ascend in the scale of being. Each side of the brain and also of the cerebellum, is supplied with separate arteries conveying blood to it, while the sinuses or canals which return the blood to the heart are common to all.
The CEREBELLUM is composed of matter similar to that of the brain in appearance, but different in arrangement,—it is separated from the brain by a strong membrane called the tentorium: its fibres originate in the medulla oblongata where the organs of the propensities take their rise, so that the brain and cerebellum although separated by the tentorium are both connected together. The brain and Cerebellum are protected by the skull, and the brain is formed before the bones which invest it. The process of ossification is gradual, the principal portion at birth being strong membranes in which the points of ossification begin and continue increasing in extent and strength till about the age of nine years: between the substance of the brain and the skull are the pia mater and the dura mater, two integuments which enclose the peripheral extent of the brain and convey blood-vessels to its several parts, the brain with these membranes exactly fills the interior of the skull. The skull fully formed is composed of eight bones which are connected by indented edges: the internal and external surfaces are, from their smooth surface called the plates and the intermediate part, diploe, which is of a loose cellular texture; as this diploe is nearly equally thick in every part, the two tables are nearly parallel to each other, and the variations where they occur do not exceed the eighth or tenth part of an inch; the integuments being an exact form of the brain, and the bony matter fitting them exactly, it follows that there is no obstacle of importance to prevent our observing the form of the brain by the form of the skull.
Disease and old age alone oppose obstacles to this proceeding; for by these causes the skull may be increased or diminished in volume, and it is generally irregular in thickness in old age: the sutures also interrupt absolute parallelism, but their situation is known and allowed for, and the frontal sinus, or cavity at the top of the nose, in the frontal bone, (which is often enlarged and covered by the schneiderian membrane giving great power to the nerves of smell) is so remotely connected that it can only affect a few organs,—five at the most. These few objections are so fully overruled by practice and observation, that they can never lead to error if the student exercise a proper degree of caution.—We may conclude then, that if men manifest their true nature in their actions, (and men cannot always be dissemblers,) the mind influencing the brain, and thereby the skull, must present a developement corresponding to their real character—and that PHRENOLOGY or external examination leads to the results sought for when we examine human nature for the purpose of self improvement, or for moral and religious elevation of character.
ON TEMPERAMENT.