Practical physiology

by Arthur Philip Beddard

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1910 ...continue the paring laterally, and in the cartilage at the side of the hinder part of the brain there will eventually be exposed one of the semicircular canals. When this is reached remove the upper wall as far as possible. In the hollow formed by the cartilage will be seen the fine membranous canal, dilating at one end into an ampulla. On continuing the exposure of the membranous canal it will be seen to join a rather large membranous sac, the utricle. Separated by a slight constriction is a smaller sac, the saccule, and at the anterior end of this is a small membranous projection which represents the cochlea. 2. Continue the dissection further so as to completely expose the three semicircular canals. Note also a tube leading towards the surface from the utricle, representing the recessus vestibuli. 3. Observe that the ampullae are more rigidly adherent to the cartilaginous walls than the length of the membranous canals. Open one such ampulla where comparatively free and note the crista acustica running transversely across the tube for about a third of the circumference. AUDITORY SENSATIONS. Range of Appreciation of Sound.--Experiment. In a room as free from noise as possible, let the subject sit with eyes closed and one ear plugged with cotton-wool. Let a watch be held in a line joining the 1 A dog-fish can be used for this dissection. two ears, and let it be placed opposite the open ear at such a distance that its ticking is just appreciable. In a quiet room this distance may vary from 2 r5 to about 5 meters. Repeat the experiment with the other ear. 2. Auditory Fatigue.--The full effect of any sudden sound tends to temporary fatigue, to abolish appreciation of the fainter echoes which succeed it. If the full effect be avoided the fainter echoes may be h...

162 pages, Paperback

First published March 13, 2013