ON THE VOICES OF ANIMALS. 
431 
make the opening narrower; he can bring the chordae at the fore 
part of the rima glottidis into contact with each other, so that 
only the posterior part of the chord shall vibrate, and the vibra¬ 
tions will be rapid, and the tone acute or high. He relaxes the 
effort, and the ligaments recede from each other at the free part, 
and they vibrate through their whole extent, and the chord is 
lengthened, and the vibrations are slower, and the tone is graver or 
lower. 
The different Sounds littered by Animals .—This is nearly all 
that concerns us in our patients. The loudness of the tone 
depends on the force of the expired air; its acuteness or grave¬ 
ness on the shortening or lengthening of the chord. It is thus 
that the tone of the bark, or neighing, or voice, depends so much 
on the age or size of the animal. Compare the shrill bark of the 
puppy with the hoarser one of the adult dog; the high-toned but 
sweet music of the beagle, with the fuller and lower cry of the 
fox-hound, and the deep but melodious baying of the mastiff: 
the whinny of the colt, and the neighing of the horse. 
The Language of Animals .—If 1 were speaking of the vocal 
organs of the human being, I should have to deserve the modifi¬ 
cation which the sound undergoes as it passes along the fauces 
and through the mouth, until it becomes speech; I should have 
to trace the connexion between the varying form and shape of the 
fauces and the mouth, and the articulation of each individual 
letter of which language is composed. 
Indeed, some such task might be required even of me, for every 
one of our patients has his peculiar—ay, and intelligible language. 
He who has long lived among horses will recognize the tone 
of delight, quickly rising into and terminating in a sharper sound ; 
the strong and elevated tone when they are calling to or chal¬ 
lenging each other, at a distance ; the short and sharp expression 
of anger; the longer, deeper, hoarser, sound of fear; the 
murmur, almost as deep, but softer, of habitual attachment, and 
the elevated vet melodious tone of sudden recognition. As for a 
dog that I once had, I could carry on a conversation with him for 
many minutes, and one perfectly intelligible on both sides. The 
difference in the acuteness or graveness of tone I could describe, 
but the manner in which the same tone is made to express 
delight or aversion, pleasure or pain, I am not sufficiently con¬ 
versant with the minute anatomy of the parts to be able to explain. 
Of the muscles by which the intensity of tone is governed I shall 
speak in my next lecture. 
As the power of speech to any considerable extent seems 
not to have been required by the quadruped, nature probably has 
not given that exquisite sensibility to the organs of voice, nor 
