CLOSUilE OF GLOTTIS BY VENTRICULAR BANDS. 639 



The ventricular bands alone offer 18*5 mm., and this may be 

 increased to 60 mm. if the glosso-epiglottidean sulcus be 

 thoroughly distended ; and the true and false together, 21 mm. 



The relatively high pressure of the true and false cords 

 together was accompanied by a bulging upwards of the glosso- 

 epiglottidean sulcus. It is possible that the inflation of the 

 ventricle tends also to push the true cords together, and that 

 thus they aid, to a slight extent, in closing the glottis during 

 expiration. 



The larynges examined were those of small dogs. 



In the ape, when the ventricular bands alone are approxi- 

 mated, inflation of the ventricles is well marked at the bases of 

 the bands. It is distinctly seen in this animal that powerful 

 expulsion of air, and especially sudden expulsion, tends to close 

 the ventricular bands, and this strongly confirms the views 

 already expressed in regard to the function of these structures. 



A sudden inspiratory effort when both true and false cords, 

 or when the true cords alone, are approximated, is seen to cauoe 

 the lateral fossae to sink considerably downwards, and the 

 resistance to the ingress of air which they afford is very great : 

 being equal to 75 mm. of mercury and more. 



When the ventricular bands alone are approximated, their 

 power of resistance is very small, unless they are firmly coap- 

 tated, when they present considerable resistance to the ingress 

 of air. But it is very improbable that in the living larynx 

 they can be pressed together in this way ; and their functions, 

 therefore, are evidently very different from that of the true 

 cords, in which the simple occurrence of a rapid inspiratory 

 movement, when the true cords are approximated, effectually 

 closes the glottis. 



Old World Ape (Small Specimen). 



Pkessube. Suction-. 



True closed True False True closed True False 



and False. closed. closed. and False. closed. closed. 



30 mm. 2-5 m. 24 m. 70-140 70-140 2-4 



Only two specimens of the human larynx were examined. 



