On the Singing of Birds. 



285 



The trachea of the common swan, a species of bird to which song is denied : —a a, the larynx in 

 the convoluted form » b, the inferior larynx ; c c, the bronchi. 



common swan, Cygnus mutus), we shall not find it short, 

 straight, and exceedingly flexible, as in song birds ; but long, 

 and often exhibiting forms still more convoluted and extra- 

 ordinary than in the above rude sketch. 



Now, as the tracheal tube of these birds is longer, wider, 

 and less flexible, than the tracheal tube of song birds, and, 

 besides, is only assisted by one pair of muscles ; it is less ca- 

 pable of producing those various intonations, and agreeable 

 sounds, which characterise the i*ringillidse and the Sylviadse ; 

 hence, the longer, wider, and more convoluted the tracheal 

 tube is, the more do the sounds produced through it resem- 

 ble those of the French horn, or the trumpet, or other bass 

 instruments, and the fewer intonations and variations it is also 

 capable of producing. 



These few observations, I think, will tend to show, more or 

 less clearly, why some birds sing, and others do not ; namely, 

 because some birds possess those requisite organs for pro- 

 ducing various sounds, while others are entirely destitute of 

 them. 



[The Cause *why Singing Birds sing.'] — Having endeavoured 

 to show that particular species of birds have certain organs in 

 every respect adapted for song, I shall now make a few ob^ 

 servations on the exciting cause of their singing. 



It will probably be more difficult to account for this, than 

 to describe the formation of the organs of singing ; and, there- 

 fore, in reply to this part of the question (for I consider the 

 question a twofold one), I would ask, do we sufficiently un- 

 derstand the language of birds, to account for the many differ^ 

 ent intonations of voice? [VII. 481 — 483. 501 — 503.] May 

 there not be some particularly sympathetic or affectionate 



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