184 VOICE MODIFIED BY THE SIZE OF THE LARYNX. 



thickness of the ligaments, and in the shape of the epi- 

 glottis. 



The larynx of birds differs from those already de- 

 scribed chiefly in this, that they have no epiglottis and 

 that the vocal chords and proper cavity of the larynx is 

 in the chest in the lower part of the wind-pipe, just 

 where it divides into the bronchiae to go to the lungs, and 

 the chink of the glottis of course being still at the summit 

 of the wind-pipe. The former parts have been called 

 by anatomists, the inferior larynx ; the latter part, the 

 superior larynx, as if there were really two larynxes in 

 birds. 



Emily. But in which of them, pray, is the voice 

 formed ? 



Dr. B. It is the opinion of Cuvier that it is formed 

 in the inferior larynx alone. He cut off the wind-pipe 

 of a black-bird near its middle, and then shook him, in 

 the same way as he would have done to make him cry in 

 the natural state. His cries were very perceptible, though 

 much more feeble than before. The same experiment 

 was performed on a mag-pie, it continued to cry, and 

 its cries were not less intense than in its natural state. 



Emily. I have heard before of hens and turkeys ut- 

 tering hoarse cries, after their heads were cut off, but 

 never imagined it was a fact observed by physiologists, 

 and explained by anatomical reasons. 



Dr. B. This structure produces a remarkable differ- 

 ence between the voice of birds and other animals. In 

 the latter, the voice being formed at the top of the wind- 

 pipe, it cannot be modified by its length or size ; while 

 in birds, the voice being formed at the bottom of the 

 wind-pipe, it is necessarily modified by the length and 

 size of this part, and of the opening at the top, for it 

 must traverse all this space before it can come to the 

 mouth. 



Emily. And is it found to be the case that those with 

 long wind-pipes have the lowest or gravest voices, and 

 those with short wind-pipes, the highest or acutest 



