642 THE VALVULAR ACTION OF THE LARYNX. 



the resistance of the mercurial column was brought to bear in 

 closing the trachea, and thus permitting the cords to resist the 

 pressure favourable to this action. 



Conclusions. 



Our experiments completely confirm those of Dr. Wyllie. 

 The ingress of air into the glottis is prevented by approxima- 

 tion of the true vocal cords, but these have very little power to 

 prevent its egress. The false cords or ventricular bands, on the 

 contrary, have very little power to prevent the ingress of air 

 into the lungs ; but when the edges are brought together they 

 act as valves and offer great resistance to the egress of air : they 

 are, therefore, to be regarded as the chief factors in the closure 

 of the glottis during exertion. . 



Although our data are insufficient to enable us to speak with 

 certainty, so far as they go, they appear to show that, in such 

 animals as do not require to have the thorax fixed, ventricular 

 bands are rudimentary or absent : that in those animals where 

 fixation of the thorax is advantageous for giving greater 

 precision or force to the movements of the anterior limbs in 

 striking, climbing, or hugging, the ventricular bands are well 

 developed. This condition is seen in the cat, lion, sloth, bear, 

 ape, and man. 



Though the power of any species of animal to vomit is not 

 entirely dependent on the presence of the false cords, yet, when 

 present, their action in closing the glottis is an important factor 

 in the act of vomiting. 



See, for description of larynges referred to, the following 

 authors, from the works of some of whom we have translated 

 largely : — 



Milne-Edwards, Legons sur la Physiologie et V Anatomic Compar^e 

 de V Homme et des Animaux^ xii, pp. 422 et seq. 



Cuvier, Anatomie Compar^e, viii, pp. 772 et seq. 



Wolff, Dissertatio Anatomica de Organo Vocis MammaliuTtu 



Herrisant, Rech&rches sur les Orgam de la Voix. 



Cyclopoedia of Anat. and Phys.^ vol. iv, pt. ii., " Voice." 



Turner, " Balcenoptera Sibbaldii" Trans. Roy. Soc. Ed., xxvi. 



Watson & Young, "Anatomy of Northern Beluga," Trans. Roy. 

 Soc. Ed., vol. xxix. 



