THE ANATOMY OF BIRD-SONG. 107 



the tongue, which in true song-birds thins 

 down to a very delicate degree. All the 

 movements of the glottis are intimately con- 

 nected with those of the tongue, so that the 

 latter organ, as will be seen presently, has 

 much to do with bird-song; indeed it has 

 much more to do with it than has the syrinx. 



Sound, as exemplified in the aviaii voice, is 

 the" vibration of a column of air by an expul- 

 sion of breath from the lungs through the 

 glottis into the mouth cavity. Properly 

 speaking, there is no such thing, as a bird 

 voice in the popular meaning of the word 

 italicised. A bird whistles, chirrups, twit- 

 ters, clucks, croaks, quacks etc. ; but every 

 sound it utters is a wind-note as pure and 

 simple, so far as if!& origin is concerned, as 

 any note of a flute. There is no such thing 

 as a bird's vocal cord. No sound ever had its 

 origin in a bird's so-called syrinx. The vibra- 

 tion of a membrane has nothing whatever to 

 do with creating the sounds uttered by birds, 

 but it may modify and vary the form of 

 those sounds. 



Without appealing to the anatomical evi- 

 dence, which, however, I shall not neglect to 

 do in the proper place, I might suggest some 

 general objections to the syrinx theory. For 

 instance, some of the pure, clear notes uttered 

 by a mocking-bird may be heard, on a favora- 

 ble morning, at a distance of nearly or quite 

 half a mile. The so-called vocal cords of this 

 bird's syrinx are less than the sixteenth of an 

 inch in length, and are stowed in a thickening 

 of the trachea some two inches below its 

 opening. Now how can it be possible for so 

 strong, clear, and pu^e a sound to be generated 

 by so short and feetife a cord, and at the bot- 

 tom of so long and slender a tube ? Let me 

 ask the reader to pause just here and whistle, 

 carefully noting that the sound is created in 



