. The elements of embryology . Embryology. VI.] THE OLFACTORY ORGAN. 161 whereas the eye is a constricted portion of the general involution which gives rise to the central nervous system. The origin of the auditory nerve has already been described. It is shewn in close contact with the walls of the auditory pit in Fig. 53. Organ of Smell. The organ of smeU makes its ap- pearance during the third day, as two depressions or pits, on the under surface of the head, a little in front of the eye (Fig. 56, N). Fig. Head of an Embryo Chick of the Thibd Day viewed sideways as an opaque object. (Ch
. The elements of embryology . Embryology. VI.] THE OLFACTORY ORGAN. 161 whereas the eye is a constricted portion of the general involution which gives rise to the central nervous system. The origin of the auditory nerve has already been described. It is shewn in close contact with the walls of the auditory pit in Fig. 53. Organ of Smell. The organ of smeU makes its ap- pearance during the third day, as two depressions or pits, on the under surface of the head, a little in front of the eye (Fig. 56, N). Fig. Head of an Embryo Chick of the Thibd Day viewed sideways as an opaque object. (Chromic acid preparation.) Cerebral hemispheres. KB. Vesicle of third ventricle. Mid-brain. Gb. Cerebellum. Medulla ob- longata. If. Nasal pit. oi. otic vesicle in the stage of a pit with the open- ing not yet closed up. op. Optic vesicle, with I. lens and ckf. choroidal fissure. The superficial epiblast moulds itself to the form of the optic vesicle and the lens ; hence the choroidal fissure, though formed entirely underneath the superficial epiblast, is distinctly visible from the outside. 1 F. The first visceral fold; above it is seen a slight indication of the superior maxillary process. 2, 3, 4 F. Second, third and fourth visceral folds, with the vis- ceral clefts between them. P. &B. 11. 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 Foster, M. (Michael), Sir, 1836-1907; Balfour, Francis M. (Francis Maitland), 1851-1882; Sedgwick, Adam, 1854-1913; Heape, Walter, 1855-1929. London ; New York : Macmillan
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Keywords: ., bookcentury1800, bookdecade1880, bookpubli, booksubjectembryology
