THE SONG SPARROW. I33 



spring. They sound like a sudden outburst of joy in the 

 midst of the universal bleakness of a winter's day — like 

 something out of its time — a melodious prophecy of the 

 joys of spring so near these last days of winter. 



We may sometimes find the Song Sparrow in a sheltered 

 place here, even in winter, and hear him lisp a faint warble 

 from near the ground, but his full song is reserved till this 

 approach of spring. The clear strokes, twitters, and trills of 

 this song are especially musical and inspiriting on this bright, 

 still morning. They have the whole vibrating capacity of 

 the atmosphere to themselves, without even the rustling of 

 a leaf or the humming of an insect to counteract them. 

 Commencing with several long and peculiarly resonant 

 notes the bird continues in a twittering warble, and ends 

 with several notes longer and more resonant than the first, 

 the whole being in a tone so loud and penetrating that one 

 cannot but marvel at the capacity of those tiny lungs, scarcely 

 larger than a small bean. But the vocal apparatus of 

 birds, and of song-birds in particular, is very remarkable. 

 The larynx, highly complicated in structure, is at the lower 

 end of the trachea, or windpipe, being also connected with 

 the upper part or fork of the bronchial tubes; and the 

 muscles connected with it, only one or two pairs in ordinary 

 birds, in song-birds, are no less than five pairs. These mus- 

 cles may change the relative positions of the cartilaginous 

 rings or half-rings connected with the vocal organ; or they 

 may lengthen or shorten the trachea, thus giving the effect 

 of tubes of different lengths in a pipe-organ, or they may 

 modify the tension of the trilling membrane and other 

 membranes of the vocal organ itself. Also the arytenoid 

 cartilages at the upper end of the trachea may open or par- 

 tially close the air passage, and so modify the sound some- 

 thing after the manner of the knee-swell of a common 



