THE RESPIRATORY SYSTEM 343 



The larynx and its vocal cords are the organ of voice- 

 production in the mammal, and the pitch of the sounds can be 

 controlled by the tension of the cords and the laryngeal muscles. 

 The false palate acts as a resonator. In the birds there is a 

 special organ called the syrinx situated at the fork where the 

 trachea divides into the two bronchi, and it is to the vibrations 

 of this that the song of birds is due. 



It is interesting to note that the power of producing vocal 

 sounds has evolved parallel with the capacity for appreciating 

 them, or in other words, the differentiation of the cochlear part 

 of the ear. 



Literature 



Goodrich, E. S. Vertebrata Craniata. Cyclostomes and Fishes. Black, 

 London, 1909. 



Oppel, A. Atmungsapparat : Lehrbuch der Vergleichenden Mikrosko- 

 pischen Anatomie der Wirbeltiere. Part 6. Fischer, Jena, 1905. 



