. Kirkes' handbook of physiology . ms, or about 2 per cent of the body weight. It exceeds in absoluteweight that of all the lower animals except the elephant and whale. Its weight, relativelyto that oj the body, is exceeded only by that of a few small birds, and some of the smallermonkeys. In the new-born child the brain (weighing 10 to 14 oz.) is about 10 per cent of theweight. At the age of 7 years the weight of the brain already averages 40 oz., and about14 years the brain not infrequently reaches the weight of 48 oz. Beyond the age of fortyyears the weight slowly but steadily declines at t
. Kirkes' handbook of physiology . ms, or about 2 per cent of the body weight. It exceeds in absoluteweight that of all the lower animals except the elephant and whale. Its weight, relativelyto that oj the body, is exceeded only by that of a few small birds, and some of the smallermonkeys. In the new-born child the brain (weighing 10 to 14 oz.) is about 10 per cent of theweight. At the age of 7 years the weight of the brain already averages 40 oz., and about14 years the brain not infrequently reaches the weight of 48 oz. Beyond the age of fortyyears the weight slowly but steadily declines at the rate of about 1 oz. in 10 years. The average weight of the female brain is less than the male; and this difference per-sists from birth throughout life. The difference amounts to about 5 oz. Thus the averageweight of an adult womans brain is about 44 oz. The brains of idiots are generally much below the average, some weighing less than 16oz. Still the facts at present collected do not warrant more than a very general statement,. Fig. 406.—Brain of the Orang, § Natural Size, Showing the Arrangement of the , Fissure of Sylvius; R, fissure of Rolando; EP, external perpendicular fissure; Olf, olfactory-lobe; Cb, cerebellum; PV, pons Varolii; MO, medulla oblongata. As contrasted with thehuman brain, the frontal lobe is short and small relatively, the fissure of Sylvius is oblique, thetemporo-sphenoidal lobe very prominent, and the external perpendicular fissure very well marked.(Gratiolet.) to which there are numerous exceptions, that the brain weight corresponds to some extentwith the degree of intelligence. There can be little doubt that the complexity and depthof the convolutions, which indicate the area of the gray matter of the cortex, correspondwith the degree of intelligence. The spinal cord of man weighs from 1 to ij oz.; its weight relatively to the brain isabout 1: 40 in the adult. As we descend the animal scale, this ratio constantly increasestill in
Size: 1744px × 1433px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectphysiology, bookyear1
