BBAID 160 BBAIN BBAID, JAMES, a Scotch physician, born in Fife, in 1795, studied medicine at Edinburgh, and settled as a surgeon in Manchester. He is noted for his re- searches on animal magnetism, which he called hypnotism. He died March 25, 1860. BBAILA, a town in Rumania, formerly a fortress, on the left bank of the Dan- ube, which divides itself here into a number of arms, one of them forming the harbor of the town. The export of grain and the sturgeon fisheries are among the principal industries. Pop. about 61,000. BBAILLE, LOUIS (bri'e), a French teacher of the blind, bom in 1809. He invented the Braille alphabet. It con- sists of a system of points printed on cardboard by indenting the reverse side. The writing is traced with the finger. He died in 1852. See Blind. BBAIN, the encephalon, or center of the nervous system and the seat of con- sciousness and volition in man and the higher animals. It is a soft white and gray matter contained in the skull of vertebrated animals. The invertebrata have, instead of a true brain, nervous ganglia, situated near the end of the body. The external gray matter is softer than the white matter and consists of variously shaped nerve cells communicat- ing with nerve fibers, and thereby re- ceiving and discharging impressions. The internal white matter is composed almost entirely of meduUated nerve fibers which transmit nerve impulses from one point to another. The brain is enveloped by three membranes called the Dura trutter, which is dense and elastic; the Arachnoid, thin and double; and the Pia mater, which covers the whole surface of the brain and supplies the nervous tissues. These support the blood vessels which nourish the cranium and the brain, and also contain a clear fluid, the cerebro-spinal fluid, which re- moves the product of the brain waste and serves like a water cushion to di- minish the effect of external shocks. The brain consists of two principal parts, the cerebrum and cerebellum, connected by bands of fibers. The cerebrum — great brain or cerebral hemisphere — oc- cupies in man the upper part of the head and is seven or eight times larger than the cerebellum, which lies behind it and below it in a peculiar cavity of the skull. The cerebrum is divided into two por- tions, the right and left hemispheres, by the longitudinal fissure, the hemispheres being at the same time transversely con- nected by a band or bridge of nervous matter called the corpus callosum. The cerebellum, like the cerebrum, is also di- vided into right and left hemispheres, connected by a bridge of nervous matter called the pons Varolii, under which is the medulla oblongata, or continuation of the spinal marrow. At the base of the brain are several masses of nervoua mat- ter or ganglia known as the corpora striata (two), and optic thala7ni (two), and corpora quadrigemina (four) ; and there are in it certain cavities or ven- tricles. Cerebrum. — The cerebrum underlies the whole vault of the cranium and cov- ers all the rest of the brain. The hemi- spheres, which are divided by a deep median fissure, are covered by a thin layer of matter, or nerve cells, and thrown into ridges or furrows called con- volutions or gyri and fissures. These ridges are the result of the folding of the cerebral surface during the growth of the brain. On the outer surface of these hemispheres is the fissure of Syl- vius, which is a deep incision at the base of the brain and runs in several directions. The fissure of Rolando runs almost vertically from the fissure of Syl- vius nearly to the border of the hem- ispheres. On the inner surface, half way between the central fissure and the rear end of the brain, is the parieto- occipital incision. These fissures form the boundaries of the various lobes of the cerebrum. (1) The frontal lobe is that part of the outer and corresponding median surfaces which lies anterior to the fissure of Rolando, and is probably associated with the exercise of the higher mental faculties. (2) The temporo- sphenoidal lobe lies below the fissure of Sylvius. (3) The occipital lobe lies be- hind the parieto-occipital fissure and in- cludes the corresponding parts on the outer surface. (4) The parietal lobe is bounded by the fissures of Rolando and Sylvius, and by the occipital lobe. (5) The central lobe or island of Reil lies at the bottom of the fissure of Sylvius and is hidden in the adult by overreaching adjacent lobes. Secondary fissures on these lobes divide them into convolutions. On the under surface of the cerebrum are two olfactory nerves and two optic nerves. The olfactory nerves cross like the letter X, wind around the two cer- ebral peduncles and terminate in the ol- factory thalami and the olfactory lobe. These peduncles pass from under the surface of the hemispheres and approach each other as they enter the Varolii. If we press apart the two cerebral hemi- spheres, we come upon the corpus cal- losum, which is a band of white fibers connecting the convolutions of both hemi- spheres. On dividing these and remov- ing some white fibers and a layer of
