DISSECTION OF THE ORGANS OF RESPIRATION.
I. The nasal cavity ([p. 243]). Review the description of the nasal cavity given under the Bones ([p. 59]). Study the cartilaginous framework that supports the external nose ([p. 243]); make a cross-section of the framework near the end of the nose and verify the description ([p. 244], and [Fig. 103]). Without injuring the larynx or tongue saw through the head in a vertical plane and a little to one side of the median line. (If desired, the brain may first be removed from the specimen and preserved for future study. For directions, see [page 462]. The removal of the brain does not injure the head for the study of the nasal cavity; the skull may be sawn lengthwise in the same way as before.) Wash out the cut surfaces before examining. Find the ventral conchæ ([p. 40]), the labyrinths of the ethmoid ([p. 43]), the inferior meatus of the nose ([p. 243]), and by bristles the lachrymal duct or canal ([p. 245]). The lachrymal duct is conveniently found by passing bristles into the openings of the lachrymal canals. One of these is to be found on the border of each eyelid, two or three millimeters from the inner angle of the eye (see [p. 410]).
Cut the œsophagus and trachea at the point where the blowpipe was inserted into the trachea. Separate the tongue, hyoid, larynx, œsophagus, and first part of the trachea from the adjacent parts and remove them.
II. The larynx ([p. 246]). (1) Read the description, studying the cartilages ([p. 247]) on a preparation ([Fig. 104]). Then very carefully remove the pharynx and its constrictor muscles, the sternothyroid and remains of sternohyoid muscles, and (2) dissect the muscles of the larynx ([p. 249], and [Fig. 105]). Dissect all those of one side first. The mucosa lining the vestibule and middle portions of the laryngeal cavity must be removed. After studying the muscles, remove the muscles and entire mucosa by scraping carefully with a dull but smooth scalpel, and study the cartilages ([Fig. 104]).
III. The trachea and lungs ([p. 251], and [Fig. 106]). The distal end of the trachea and lungs may now be removed with the heart from the body. The lungs may be inflated with the bellows. The bronchi should then be exposed, cleaned, and followed as far as possible into the lungs. The heart should be preserved for future study.