330 Prof. T. P. Anderson Stuart. [Jan. 21, 



to cover the voice-box lias given a longer life to the time-honoured 

 doctrine of the functions of the epiglottis than it would otherwise 

 have had; it seemed so beautifully fitted for its office that until 

 recently it did not occur to any one to question it. Upon considera- 

 tion, however, of the part played by the arytenoid valve according to 

 my account, it appears to be much more beautiful than the part 

 played by the epiglottis in the old account of the closure of the 

 larynx, for, in addition to the merit of being demonstrably true, it 

 co-ordinates and explains many observations hitherto without any 

 connecting link or explanation, as will be set forth later on. In the 

 meantime, however, I may point out how this arytenoid valve stands 

 at the parting of the ways downwards out of the pharynx : when it 

 stands backwards the food-passage is closed and the air-passage is 

 open, when it lies forwards the air-passage is closed and the food- 

 passage is open. Thus it can make, as it were, a funnel forwards 

 into the air-tube or a funnel backwards into the food-tube. In short, 

 and to use a particularly Australian illustration, it stands like the 

 little movable gate by which sheep are drafted out of the common 

 yard into separate pens it drafts the air forwards and the food back- 

 wards. 



This use of the term funnel is fully justifiable. In ordinary respira- 

 tion, especially during inspiration, since the top of the arytenoid flap 

 lies against may even indent the posterior pharyngeal wall, the way 

 to the gullet is stopped, while the vestibule of the larynx is wide and 

 patent, and, of course, is wide at the entrance and narrows downwards 

 to the glottis. In this condition the shape of the entrance is appa- 

 rently five- sided, though really there is a sixth, but comparatively 

 small, side in the middle line posteriorly, where the transverse aryte- 

 noid muscle is. The anterior side is formed by the epiglottis. The 

 lateral margins consist each of an anterior moiety formed by the ary- 

 epiglottic fold, and of a posterior moiety containing the arytenoid 

 tips and Santorinian cartilages. When the larynx of the Goat is 

 exposed, this anterior funnel is peculiarly striking during forced in- 

 spiration, and the superior margin of it is almost circular, the violent 

 outward and backward movement of the arytenoid tips pulling back- 

 wards the margin of the epiglottis, and so rounding off the anterior 

 angles, and the flexible tips of the arytenoid and Santorinian cartil- 

 ages yielding to the pull of the ary-epiglottic folds, and so rounding 

 off the lateral angles. 



The posterior funnel, though less striking, is hardly less real than 

 the anterior one. It really exists only during the act of swallowing, 

 and then also its anterior wall is composite and somewhat irregular. 

 The anterior wall is formed above by the epiglottis, in the middle 

 by the back of the arytenoid flap, and below by the back of the 

 lamina of the cricoid. Now, while the epiglottis is always more or 



