. Anatomy, descriptive and applied. Anatomy. 850 THE NERVE SYSTEM The brains of the microcephalic idiots are far under the minimal size necessary for mental integrity, which is about 1000 grams (35 ounces avoirdupois) in the male and 900 grams ( ounces avoirdupois) in the female. Certain idiotic individuals possess brains of normal size or even abnormally large brains, but structural defects underlie these forms of idiocy. The whale, porpoise, dolphin, and elephant possess larger brains than man, but relative to the size and weight of the body the human brain is proportionately Th
. Anatomy, descriptive and applied. Anatomy. 850 THE NERVE SYSTEM The brains of the microcephalic idiots are far under the minimal size necessary for mental integrity, which is about 1000 grams (35 ounces avoirdupois) in the male and 900 grams ( ounces avoirdupois) in the female. Certain idiotic individuals possess brains of normal size or even abnormally large brains, but structural defects underlie these forms of idiocy. The whale, porpoise, dolphin, and elephant possess larger brains than man, but relative to the size and weight of the body the human brain is proportionately The Development of the Brain and the Usual Classifications of its Sub- divisions.—The cephalic region of the embryonic neural plate is characterized, as already pointed out (p. 804), by a rapid process of expansion and intensity of growth energy which seems to indicate the higher functional potentiality of what is to become the brain. The fusion of the margins of the neural plate, proceeding rapidly cephalad and caudad from about the cervical region, soon effects the complete closing in of the brain portion of the neural tube and its complete separa- tion from the overlying ectoderm. For a brief period prior to the completion of the tube formation there exists a minute opening affording communication be- tween the interior of the neural tube and the surrounding amniotic cavity; this temporary passage is called the neuropore (Fig. 620), and is morphologically the cephalic end of the tube. Its adult position is probably in the hypophyseal. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Gray, Henry, 1825-1861; Spitzka, Edward Anthony, 1876-1922. Philadelphia, New York, Lea & Febiger
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1913
