10 INTRODUCTION. 



In MACGILLIVRAY'S description of the Structural anatomy of 

 the organs of tune in birds, we find it stated that the trachea is 

 an elastic tube, very flexible and contractile, so that it can accom- 

 modate itself to the various motions of the neck ; it is covered 

 with layers of cellular tissue, and commences just behind the 

 tongue, extending downwards to opposite the first rib, where, at 

 the syrinx, as it is called, or inferior larynx, it is divided into 

 two bronckii. The parts which correspond with these in man 

 and animals are proportionably larger and more complex, be- 

 cause with them the varieties of tone in the voice are produced 

 by the muscles and chords of the larynx ; whereas in birds, the 

 sound is produced at the syrinx, or lower extremity of the wind- 

 pipe, the modulations being caused by the contraction and ex- 

 tension of the larynx. The vocal chords which vibrate under 

 the impulse of the air, and so produce sound in the human larynx, 

 are placed in that organ. But in the case of birds the vibrating 

 membrane is placed in the lower larynx, or, more properly speak- 

 ing, the syrinx. Such then is the apparatus by which the voices 

 of birds are attuned, and this is the modus operandi : when 

 the air contained in the lungs and air-cells passes through the 

 bronchii, it causes the vocal membrane at the extremity to vibrate, 

 and the sound which is thus produced is rendered acute or grave, 

 by the relaxation or tension of the parts ; while the stream of 

 air thus caused to vibrate is narrowed and divided, or suffered to 

 pass free, according as the muscles of the lamjnx are tightened 

 or relaxed. This author cannot, however, in his careful ana- 

 tomical researches, find an adequate cause for the great variation 

 observed in the songs of different birds. He says : " The modi- 

 fication of these organs presented by the different species are 

 slight ; the parts in all I have examined, being the same, and with 

 the same number of muscles. The peculiar song of different 

 species must therefore depend on circumstances beyond our cog- 

 nition ; for surely no one could imagine the reason that the Rook 

 and the Hooded Crow require as complex an apparatus to pro- 

 duce their unmusical cries, as that which the Blackbird and 

 Nightingale employ in modulating their voices, so as to give rise 

 to those melodies which are so delightful to us ; and yet the 

 knife, and the needle, and the lens, do not enable us to detect any 

 superior organization in the Warbler over the Crow." 



By some authors the superior powers of song manifested by 



at all events, they are entitled to a higher place ; and then, why was not the Bull- 

 finch included, and several other very sweet songsters, whose names do not appear ? 

 Great difference of opinion will, of course, at all times prevail, respecting the com- 

 parative merits of the various individuals of the feathered choir : so much depend- 

 ing upon the taste and temperament of the hearer, and the circumstances under which 

 they are heard, as well as upon the state, and condition, and opportunities of im- 

 provement which the singer has enjoyed. 



