26 Kitchen on the Inferior Larynx in Birds. [January 



walls at the sides, and by the diaphragm at the bottom. The 

 muscular motion in these parts alters the shape of the chest, 

 alternately enlarging its cavity and drawing air into the lungs ; 

 and then compressing those organs, driving out the air via the 

 bronchial tubes, trachea, larynx, nasal passages, and mouth. (2) 

 The phonating structure, which is the larynx, having a frame- 

 work of cartilages known as the thyroid, the cricoid, and the two 

 arytenoids ; but whose essential parts are the two fibrous lips, or 

 projections from the sides of the larynx, known as the vocal cords 

 or ligaments, and the muscles that are attached to these liga- 

 ments and cartilages, for the purpose of rendering the former 

 more or less tense, of drawing them apart, or of approximating 

 their edges to various degrees, and of regulating their shape. 

 The interposition of these vocal ligaments in various degrees of 

 tension, approximation, etc., in the tract of the air-blast coming 

 from the lungs, is the means of breaking up the air-column into 

 the vibrations which produce the effect upon the ear known as 

 vocal sounds. (3) The resounding cavities, which modify the 

 sounds as to their power and other qualities. These cavities are 

 the trachea and bronchial tubes, which reverberate the chest 

 tones, and the throat, mouth, and nasal passages, which are in- 

 strumental in forming the head tones. The various positions and 

 actions of these latter cavities and their contained parts, such as 

 the tongue and soft palate, give the various effects of articulation 

 to speech, as well as song. It must be noted that there is no di- 

 viding line between speech and song, the one gliding into the 

 other, and that articulation is distinct from phonation. A whis- 

 per may be articulated speech, without sound being produced by 

 the larynx. 



This in brief being the structure of the human vocal appar- 

 atus, how does that of birds differ from it? (1) In the respira- 

 tory method, and in the structure of the respiratory mechan- 

 ism. Almost the whole body of the bird is the air-bellows 

 and reservoir. There is no diaphragm separating the chest 

 cavity from the abdominal cavity, or at least it is very rudimen- 

 tary, excepting in some birds like the Apteryx, where it is more 

 nearly like that of mammals. Air passes through the bird's lung 

 and out of it by numerous apertures on the pulmonary surface, 

 to the various air cavities of the abdomen, neck, bones, etc. 

 Here is a very large pneumatic storage cavity. In birds, the 



