648 ANIMAL PHYSIOLOGY. 
the animal closely enough when producing the various vocal 
effects naturally. 
All of our domestic mammals have vocal bands and a larynx, 
not as widely different from that of man as might be supposed 
from the feeble range of their vocal powers. : 
The actual behavior of the vocal bands has been studied 
experimentally in the dog when growling, barking, etc. And, 
so far as it goes, this mechanism of voice production is not 
essentially different from that of man. Growling is the result 
of the functional activity of the vocal mechanism, not unlike 
that of man when singing a bass note; barking, of that analo- 
gous to coughing or laughing, when the vocal bands are rapidly 
approximated and separated. 
The grunting of hogs and the lowing and bawling of horned 
cattle is probably very similar in production, so far as the 
larynx is concerned, to the above. The cat has plainly very 
great command over the larynx, and can produce a wide range 
of tones. 
The quality of the voice of most animals appears harsh to 
our ears, owing probably to a great preponderance of over-tones, 
in consequence of an imperfect and unequal tension of the vocal 
bands; but the influence of the su- 
pra-laryngeal cavities, often very 
large, must also be taken into ac- 
count. 
In certain of the primates, and 
especially in the howling monkeys, 
large cheek-pouches can be inflated 
with air from the larynx, and so add 
to the intensity of the note produced 
by the vocal bands that their voice 
may be heard for miles. Song-birds 
produce their notes, as may be seen, 
by external movements low down at 
Fie. 486.—Lower larynx (Syrinx) of 
crow (after Gegenbaur). A, seen 
from side; B, seen from in 
front. a—f, muscles concerned 
in movements of lower larynx ; 
g, Membrana tympaniformis in- 
terna, stretching from median 
surface of either bronchus to a 
bony ridge (pessulus) which pro- 
jects at the angle of bifurcation 
of trachea. 
the bifurcation of the trachea (sy- 
rinx). The notes are owing to the 
vibration of two folds of the mucous 
membrane, which project into each 
bronchus, and are regulated in their 
movements by muscles, the bronchial rings in this region being 
correspondingly modified. 
A large number of species of fishes produce sounds and in 
a variety of ways, in which the air-bladder, stomach, intestines, 
