THE MAMMALIA— MAN AND BEASTS. 
93 
The Mammalia clifTcr considorahljr from Birds, in respect to their organs of voice. 
In the latter, the several varieties of sound are produced in a more simple manner ; 
and, from the organs of voice in the Birds approaching very near, in the principles of 
their structure, to several well-hnown musical instruments, they are, at tho same 
time, more fully understood. But the cries of the Mammalia are most commonly of 
a very complicated and discordant nature, so that we may attempt in vain to imitate 
them by any mechanical means. 
In ordinary language, we understand by the term rofee, those sounds wditch ani- 
mals produce in expelling the air from their lungs, through the opening of the glottis. 
From the above definition, it follows, that animals with lungs, being the first three 
Classes of Vertebrated Animals, the Mammalia, Birds, and Reptiles, can alone enjoy 
this power. 
The voice, being formed of vibrations communicated to the air, consists, like all 
other sounds, of three orders of properties, perfectly distinct from each other t (1.) 
The tone, or the different degrees of depth and acuteness, which depend on the slow- 
ness or rapidity of tho vibrations ; (2.) The intensilyy or different degrees of loud- 
ness, regulated by the extent of the vibrations; and, (3.) The qunlitijf which de- 
pends upon a variety of circumstances hitherto undetermined, relative either to tho 
internal structure, the substance, or the figure of the sonorqus body. Man alone 
being capable of speech, becomes susceptible of a fourth order iff modifications, which 
we represent by tho letters of the alphabet. These may ho further divided into two 
sub-orders — the one, relative to the principal sounds, which w'e represent by voweh ; 
and the other dependant upon their mode of articulation, and distinguished by the 
f-onsonants. Tliose circumstances which give rise to the several qualities of tone, 
and the articulate words of Man, are still involved in great obscurity, although tho 
investigations of Do Kempelin in 1791. and the more recent ex^iei'imcnts of Messrs 
Willis and Wheatstone, demonstrate that it is not impossible to imitate the sounds of 
the human voice by certain mechanical cuxitrivances. 
In respect, however, to the tone and intensity of sounds, the theory has long been 
Well understood. We know that the rapidity of the vibrations of cords is inversely 
proportional to the length of the latter, and directly proportional to the degree 
their tension. It is also ascertained, that a cord producing a tone will give 
4t the same lime others corresponding to the aliquot parts of its length, such 
as the half, the third, or the quarter ; and tho sountls thus formed arc termed 
harmonic tones or chords. The vibrations of the entire cord coincide with tho 
smaller but more rapid vibrations of the aliquot parts, and the sounds thence resulting 
are found to be haimonious, or agreeable to the ear. We further know that wind 
instruments of music can produce sounds correspunding to their total length, at the 
*ame time that they emit others relative to the lengths of their aliquot parts ; and 
that it merely requires some apparently very slight cause, whether with cords or 
wind instruments of music, to occasion one of these partial or harmonic tones lo prc. 
vail over the whole or fundamental tone. It has also been remarked, in respect to 
the tubes of wind instruments, that their form, in most cases, does not affect the 
fone. If the extremity opposite to the embouchure be closed, they produce a sound 
corresponding to a tube of twice their length, but when it is only partially closed, as 
'uthe chimney or fonuel-pipcs of the organ, the tone is always more grave than if it 
had been open, but less so than when entirely closed. Wind instruments of music can 
omit no sound by simply blowing Into tho tube. There must be at the entrance of 
the tube some sonorous body, that is to say, a thin jdanc capable of vibrating, or at 
least of breaking the current of air against its edge. This condition is absolutely 
<sssential to the production of sound, properly so called. 
The organ of voice, being found only in animals possessing lungs, always consists 
of the canal formed by the bronchial tubes, tho trachea, and the mouth ; in other 
^ords, of an irregular tube to which the lungs act as hollow's. The planes capable 
of breaking the air and jnoducing a true sound may, however, be placed in different 
positions relative to the length of the tube. I'he entire portion compri'jcd between 
the vesicles of the lungs and those vibrating planes, which have received the name of 
Slottis, may be t’on.sidered as nothing more than the nozde of the bellows. That 
portion of the tube placed beyond these planes, being the lurynxy must alone be 
regarded as the sonorous instrument, whose length and other circumstances serve to 
influence and modify the voice. 
IMany Birds arc found to possess, in the interior of their bronchial tubes, small 
planes, being a kind of rudimentary glottis ; but all of them have a complete one at 
the point where their bronchial tubes unite in forming the trachea. On this account 
should thence regard the trachea itself in all Birds as a true musical instrument, 
the Mammalia :ino Uqjtiles, on the contrary, no glottis is found except at tho 
'^Pper extremity of the tnichea, where it enters the mouth, Wc must, therefore, 
consider the mouth in these animals as the real instrumeut of music, and the trachea 
'''dh them is merely a wiml-pipo or portovent. 
It thus appears I hat the voice of animals is formed by the air which is discharged 
from the lungs by the muscles of oxi)iration; that it traverses the bronchial tubes, 
sometimes also the trachea ; and arrives at a contracted portion, edged with two 
^hin and flexible planes, called the glottis, where the sound is really produced. It then 
traverses a second tube, consisting either of the trachea and mouth or of the mouth 
solely, where it receives the last modification'i, from the length, the form, and the 
'lifforencos in ihe complication of these cavities. Finally, it passes between the lips, 
"'■faich may be more or less opened or diflerently formed. 
Iho possiliie intensity of the voice depends u])on the proportional volume of the 
and aerial cavities, and hence results the extniordiiiary volume of voice possessed 
y niost Birds. The facility of modulating the voice during singing depends upon 
facility of motion possessed by the muscles which contract the lungs. That por- 
of tile trachea or the bronchial tubes, situate within the glottis, eainiol infiucnco 
^ quality of the sound, excepting, perhaps, that the proportion of its diameter, in 
I’ospect to the glottis, may influeni*e the possible velocity of the air in its passage. 
'G glottis itself affeels the sound like the embouchure of a wind instrument of mu- 
while that portion of the canal situate externally to it acts like tho tube of the 
'“stnunent, inasmuch as its several lengths determine the respective fundamental tones 
'Cl the animal can assume; while tho glottis, by its tension and the shape of its 
2-i 
orifice, occasions the several harmonic tones of the fundamental note belonging to each 
particular length. The external opening may lastly he compared to the remote ex- 
tremity of the organ-tube, which may be more or less closed. Upon the facility with 
which an animal can vary these three conditions depends the extent and flexibility 
of its voice. 
Those modifications which wc represent by the letters of the alphabet, are formed 
in the mouth, and depend upon the greater or less power of motion possessed by the 
tongue, and especially by the lips, to which circumstances Man owes the superior 
power of speech. Some animals which seem to possess considerable flexibility in their 
organs of voice have certain additional parts, nullifying the advantageous form of the 
others, such as cavities, in which the air is obliged to circulate after leaving the 
glottis. 
In respect to the Mammalia generally, we are far from having a complete know- 
ledge of their manner of producing those disagreeable and complicated noises which 
our musical instiuments fail to imitate. A few general facts have, however, been as- 
certained. Thus, the interval of the fibrous, and more or less sharp, cords of the 
larynx, placed on the upper extremity of the trachea, and called tho vocal cords, is 
the place w'here the sound is formed ; while tho size, freedom, and tension of these 
cords influence the sound at its very origin. As the entire trachea serves merely as 
a wind-pipe, it varies little in its form. The rings are scarcely ever complete, but 
leave behind them a simple, membraneous band. 
The sound produced by tho vocal cords, or inferior ligaments of the glottis, may be 
modified, 
1 . By the form and dimensions of the passage opened for it as it traverses the 
remaining parts of the larynx ; 
2. By the resounding or dispersion of the sound in the cavities contiguous to the 
larynx, such as the ventricles of the glottis, the furrows and pouches which some- 
times communicate with it, or the pouches which occasionally open in front of the 
larynx ; 
And, lastly, By the form and dimensions of the double passage furnished by the 
mouth and nostrils, or by the different positions of the tongue and lips. 
It would be inexpedient to pursue this subject in detail at present, and our further 
observations upon those modifications which influence the voice will be found under 
the specific descriptions. 
GENERAL REVIEW OF THE MAMMALIA CONTINUED. 
Anomalous adaptations for motion and prehension, — Special organizations for 
fl/ing, and swhnming. 
Altitough some Mammalia possess the power of plunging in the water, of elevating 
themselves in the air, or of burrowing under ground, these seem rather to be anoma- 
lous states of existence. The normal or proper state of their organization fits them 
more especially for terrestrial animals. 
Among those destined to reside upon the earth, Man alone has his fore extremities 
adapted solely for prehension, and his hinder limbs for maintaining the body in an 
erect posture. We shall merely remark at present, that he owes this vertical posi- 
tion chiefly to the size of the soles of his feet ; the largeness of the muscles belonging 
to the legs and thighs; the breadth of the pelvis; the position of the head upon the 
neck ; and the shortness of the arms when compared with the length of the logs. It 
follows from these arrangements, that his forward movement consists simply in the 
successive position of tho lower extremities one before the other and in parallel lines; 
while running differs hut little from walking, except in the greater rapidity of the 
action. 
It is ditTorent. in the true Quadrupeds, where the extremities arc very nearly of equal 
length. In these wc have a variety of modes of progression ; such as the walk or 
pace, where the two diagonal feet, cither the right fore and the left liind foot, or the 
loft fore and the right hind foot, act successively, Imt in such a way that the advance 
of the fore foot is almost instantaneously followed by tho advance of the hind foot on 
the opposite side, so that the four feet are raised and set down one after another. In 
a more rapid pace, being the trot, the two feet diagonally opposite rise and are set 
down at the same instant. The canter or common gallop, the full gallop, and the 
arable, have been already explained (see page 26), as well as the auhiny or Spanish 
amble, and the pas rdeve of French authors (see page 63). 
The greater number of Quadrupeds, when they wish to advance slowly, go at a 
simple walk. The trot is the proper motion of certain species, such as the Horse 
the I^x, some races of Dogs, the Bear, and of the Elephant when hurried. The 
amble is the natural pace of certain races of the Horse and Dog, and invariably so 
with the Hyrana, which circumstance gives a singular and striking appearance to the 
gait of that animiil. The canter, and especially tho full gallop, are used by most land 
Mammalia when hotly pursued, or when they are in pursuit of any prey. 
Those Mammalia having the fore extremities much longer than the hinder, are pre- 
vented from walking upright like Man, or on the four feet liltc ttie Quadrupeds. The 
position of their body is therefore oblique, and their speed on a flat surface being very 
limited, they are more disposed to climb trees than tii use any other kind of exercise. 
Tliore are other Mammalia, such as the Jerboas, tho Gcrhils, the Kangaroo, and the 
Kangaroo- Rat, whore tho hinder are very considerably longer than the fore legs, which 
scorn by their excessive shortness to depart as much iu defect from the ordinary size 
as tho others do in excess. The.se animals walk with great difficulty. The Kanga- 
roos in particular make use of their tail, whicli is of considerable strength and size, 
either to counterpoise Ihe weight of the fore extremities, or to assist in raising tin; 
body, while the fore ])aws touch the ground. When they run, or rather jump, for 
such is tlieir real motion, the hinder feet alone act, and propel the body to a consider- 
able distance in advance. The tail, however, follows to their assistance, and tlie 
moment the feet touch the ground, it extends and forms with the two metatarsi a 
kind of tripod, which maintains their upright position, and enables the animal to exe- 
cute a new leap. As another instance of this kind of movement, we may adduce tlie 
Jerboas, animals abowt the size of a Rat, with their hinder feet much longer in pro- 
