The frog: an introduction to anatomy, histology, and embryology . -brain;C, pericardial cavity; CV, vesicle of cerebral hemispheres ; I, infundi-bulum ; L, liver ; N, notochord ; o, depression of floor of fore-brainfrom which the optic vesicles arise; OE, oesophagus; P, pituitarybody; PN, pineal body; S, central canal of spinal cord : SO, stomo-dseum ; T, truncus arteriosus ; V, ventricle ; Y, yolk-cells. spinal cord. The lumen or cavity of the tube persists as the central canal of the spinal cord and the ventricles of the brain. The Brain. At the time of its first appearance the brain is bent
The frog: an introduction to anatomy, histology, and embryology . -brain;C, pericardial cavity; CV, vesicle of cerebral hemispheres ; I, infundi-bulum ; L, liver ; N, notochord ; o, depression of floor of fore-brainfrom which the optic vesicles arise; OE, oesophagus; P, pituitarybody; PN, pineal body; S, central canal of spinal cord : SO, stomo-dseum ; T, truncus arteriosus ; V, ventricle ; Y, yolk-cells. spinal cord. The lumen or cavity of the tube persists as the central canal of the spinal cord and the ventricles of the brain. The Brain. At the time of its first appearance the brain is bent at right angles about the middle of its length ; the axis of THE BKAiN 119 the anterior portion being vei-tical, and that of the posteriorportion horizontal. (Fig. 27.) The posterior portion, or hind-brain, BH, is wide from side to side, and has moderately thicksides and flooi, but a thin roof; it is continuous behind withthe spinal cord. The anterior or vertical portion has walls of nearly uniformthickness in all parts. It is divided by a slight Fig. 29.—Longitudinal vertical section through the head andanterior part of the body of a tadpole about the time of appearance ofthe hind legs. Length of tadpole, 12 mm. X 14. A, auricle of heart; AD, dorsal aorta ; BB, basi-branchial cartilage ;BF, fore-brain ; BH, hind-brain ; BM, mid-brain; C, ccelom or bodycavity; C, pericardial cavity; CH, cerebral hemisphere; CB, rudi-mentary cerebellum ; CP, choroid plexus of fourth ventricle ; CP,choroid plexus of third ventricle ; F, pharynx; G, stomach ; H, lung ;1, infundibulum ; d, horny jaws; K, lip; L, liver; N, notochord;O, depression of floor of fore-brain from which the optic nerves arise ;OE, oesophagus; P, pituitary body; PN, pineal body; S, centralcanal of spinal cord ; T, truncus arteriosus ; V, ventricle. best marked at the sides, into an upper or posterior part, themid-brain, BM, which forms the angle of the bend and liesopposite the anterior end of the notochor
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectbiology, bookyear1896
