636 THE VALVULAR ACTION OF THE LARYNX. 



manometer ; the arytenoid cartilages and the vocal cords were 

 then approximated, as well as the ventricular bands when these 

 were present. The strength of current which these structures 

 could resist in various positions, and during inspiration and 

 expiration, was estimated by the height at which the water or 

 mercury stood in the manometer. A curved needle was passed 

 through the bases of the arytenoids which were then coaptated 

 by means of a figure-of-eight ligature. In some experiments in 

 which the larynx possessed cords of such dimensions as to 

 admit of it, needles were passed through the thyroid cartilage, 

 one on either side of the middle line, and just external to the 

 anterior attachment of the false cords, and the points were 

 pushed backwards inside the edge of the false cord towards the 

 arytenoid cartilage. In this way, approximation of the cords 

 could be easily produced by movement (separation) of the eye 

 end of the needle. In smaller larynges, however, approxi- 

 mation was assisted by seizing the coaptated edges of the cords 

 with a pair of fine pointed curved forceps. Lateral pressure 

 was exercised by means of a weighted scale pan which was 

 connected with a movable concave surface of wood placed 

 externally over the line of attachment of the cord to the wall 

 of the larynx. 



This was aided or substituted by manual pressure, and 

 manipulation was also resorted to in pushing the base of the 

 tongue with the epiglottis backwards over the larynx. 



In the sheep the ventricular bands are absent. The follow- 

 ing figures represent the result of these experiments : — 



Resistance. 



In millimetres In inches 



of mercury. of water. 



Experiment 1 4 2 



2 5 2-5 



„ 3 8 4-25 



Average about 5 '5 8 



On blowing upwards through the glottis, the true vocal cords 

 being closed (no false cords). 



On sucking air downwards through the glottis, the resistance 



