SONG OF BIRDS. t79 
The vocal apparatus in Birds, represented in Fig. 69, is 
very complicated, and differs from the human larynx and trachea. 
It consists of a kind of osseous chamber ; which, however, is only 
a swelling in the arterial trachea at the point where it bifurcates 
and enters the breast to form the bronchial tube. It is this 
formation, called the lower larynx, which constitutes the organ of 
song. Five pairs of muscles, attached to the walls of this chamber, 
stretch or relax the vocal chord, by which means they enlarge 
or diminish the cavity of the larynx. Whoever has watched a bird 
singing must have noted the swelling and contracting of its throat 
Fig. 69.—Vocal Apparatus contracted and distended. 
as it poured out its melody, modifying in a thousand ways the 
tension of the vocal chords, and producing those marvellous modu- 
lations the perfection of which must always be a subject of astonish- 
ment and admiration. 
The song of Birds must be the expression of some sentiment ; 
for they sing as much for their own pleasure as to charm those who 
listen to them. While filling the woods with their melodious accents 
they direct their gaze on all sides, as if proud of their talents, and 
desirous of gathering the tribute of admiration to which they feel 
themselves entitled. Their song varies with the season, but it is in 
the early spring their efforts are most admired for their beauty of 
harmony. Can anything be more fascinating than the warbling of the 
linnet, the piping of the goldfinch, or the melodious cadence of the 
nightingale, as it breaks the silence of the woodland during the 
serene nights of leafy June ? 
Our landscapes would be sad and mute indeed without these 
