THE MAMMALIA_MAN AND BEASTS. 
83 
The young are at first nourished entirely by the Milk secreted from the Mammae 
or breasts of their mother. Each mamma is a conglomerate gland, covered with a 
tenacious cellular tissue ; it is formed of rounded grains, separated from each other 
by fat, and surrounded by spongy and cellular tissues. In the midst of this gland, a 
number of lactiferous canals cross each other, being semi-transparent, susceptible of 
dilatation, andro-uniting in several leading branches towards the nipple. Besides this 
general conformation, there are several thoracic, epigastric, or hypogastric arteries, 
independently of numerous lymphatic vessels, which carry their ramifications through- 
out these organs. They are also very numerously supplied with nerves, for their 
sensibility is very great. The nipple, which is only covered by a mucous tissue, 
with a very fine skin and epidermis, is delicately sensible to the slightest touch. 
“ Elio est formce il’un tissii vasculaire particulier qui jouit do la propricte d’entrer en 
uno veritable Erection analogue a cclle de la verge et tlu clitoris; car ces organes ont 
beaucoup dc sympathie entro eus. Elle rcfyoit de sang et devient rouge et tres-sen- 
sible alors. Les conduits s’ouvrent et sont prets a falrc jaillir le lait do meme que 
le spormc est fjacule par los canaux excretcurs des vcsicules seminales. En effet, 
ii y a unc grande rcsscmblance enlre Taction de la glando inamraaire et colic des 
organes de la generation.” 
The mamma? nmy be placed, acconlin ^ to the species, on the breast, the groin, 
or the abdomen. Their number is often relative to that of the young. In the larger 
species, which have only one or two young at each birth, there are usually but two 
mammfe, whether pectoral or ventral. AVith the species of medium size, there are 
most commonly eiglit ; although some may have as many as fourteen. 
1'lifi Carnivorous animals most commonly liavc from six to ten placed longitudinally 
under the abdomen ; the 0])ossums and Kangaroos have four to eiglit, fixed within 
a fold of skin, or inguinal purse, within which the young lodge securely. The Elephant, 
as also the Quadrumana, usually have two upon the breast, as in Man. Tliu female 
Hog has from ten to twelve, and the Ruminantia, whose milk seems to bo more sub- 
stantial than lliat of any other domestic animals, have generally two to four mammro. 
Tlie.se numbers point out the maximum limit to the number of young, which each 
female, when in a healthy state, is capable of nourishing without inconvenience. 
Among the gregarious tribes of Mammalia, the young recognise their mother with 
surprising accuracy by the sound of her voice, or by the smell, in the mitlst of the 
most numerous flock. Those young possessed of the greatest vigour will, however, 
take milk from several mothers, at the expense of the weakest, which are thus de- 
prived of a portion of the food intended for them by Nature. Some unnatural 
mothers drive their young away on first approaching their udder, without exhibiting 
the slightest compassion for the unprotected state of their offspring, which are thus 
in general left to perish. 
With the greater number of Mammalia, the young take and leave the breast ac- 
cording to their wants ; but it is different with tho IMarsupialia, the young of which 
attach themselves m forcibly to the mammie, that they would rather permit them- 
selves to be decapitated than leave the nipple. They remain continually in this 
position until their bodies become entirely covered with hair, and they possess strength 
sufficient to gambol around their mother. Among most species of this singular (dass 
of Mammalia, the skin of the abdomen forms a purse or pocket containing tho mam- 
mas and to which cavity the young resort for refuge, oven after the time when they 
cease to derive their sustenance from tlicir mother’s milk alone. Only two species 
of Mammalia, the Ornithorhyuchus and Echidna, are without any apparent raarama? ; 
but many interesting questions regarding their habits, and especially tho cares wdiich 
they bestow upon their young, still remain unsolved. 
It has been said that tho young Elephant sucks with its trunk. This, however, is 
an error, as it makes use of its mouth, in nearly the same manner as other Mam- 
malia. 
The time of suckling varies with the period of gestation, as well as with the time 
necessary for the growth of the young. Thus it is prolonged as long as the ninth or 
tenth month in Man, the Horse, and the greater part of the larger quadrupeds, while 
it is very short with the Uodontia, which have in each year a considerable number 
<^f births. With the Guinea-])ig, which is the most fertile of known Mammalia, the 
period of lactation terminates in about twelve or fifteen days. 
After having fed their young during the days immediately succeeding to the period 
of birth, entirely with the milk of their niammfc, the females of the Carnivorous 
animals take themselves to the chase, and bring home to their young different kinds 
of prey, so as gradually to accustom them to the use of a more solid food. At this 
tunc they seem to lose their natural ferocity, and gambol with their young ; but on 
being attacked, they are only thereby rendered the more formidable. After liaving 
fried every possible means to place their family in a place of security, they fight witli 
fhe most determined obstinacy and courage. The particular history of each species 
exhibits, in general, many interesting details relative to the care which the female 
lakes of hqr young, until they are sufficiently strong to provide for themselves. As 
* 0011 , however, as they have attained this period, the mothers are often seen suddenly 
change their feeling towards their progeny, and drive away, with the greatest 
*^bstinacy, the same young ones which had so long been the continual objects of 
»eir warmest attachment. This is particularly tffiservablo in all those species which 
®^perience a rut at a particular period of tho year, and also most remarkably among 
0 larger Carnivorous animals, who would soon become pinched for want, if too 
'^xny Wore permitted to reside together in the same district. 
It is commonly during the interval which elapses between the termination of lacta- 
tion and the commencement of puberty, that tho first or milk teeth are replaced by 
Qrs* This only happens to those species which have simple teeth, fixed by true 
oots. It begins with the incisors, and ends with the nmlars, while it often happens 
the latter are not changed until long after the age of puberty. The Hog never 
its first teeth, as they do not fall, but always continue growing. In certain 
tho teeth continue to grow during the whole course of their lives, 
*amc incisors of the Rodentia, tho compound molars of some animals of tho 
teeth those of the Elephants. The same property is observed in tho 
niol ** Idling, iroos as well as in the Elephants, but with this difference, that the 
3 are developed from tlie back, of each jaw forwards, and do not grow out of the 
gums as in most other Mammalia. There are, however, numerous variations in these 
respects among the several genera and species, as well as in tho forms, which the 
teeth present, according to the respective ages of the animals. Thosci Mammalia 
which change their teeth, and especially the Caimassicrs, experience at this critical 
period the most painful nervous affections, which often prove fatal. 
In general, the term of life among the Mammalia is in direct proportion to the 
time which they severally take in arriving at their full growth, exclusive of the period 
of gestation. Buffon calculated, from many observations, that they lived seven times 
the period of growth ; but it is very often only six times this period. 
Among the most remarkable exceptions to the above rule, we find Man, with whom 
the average duration of life is far less than that of other species, relative to his time 
of growth. As he does not attain his full size until about the ago of twenty years, 
his life ought to average a duration of 120 to 140 years. Several individuals have 
attained these ages, and some have even passed them ; but of those few who survive 
the first years of infancy, by far the greater number do not pass beyond the ages of 
seventy or eighty. This anomaly to the rule of Buffon is due to a multitude of 
circumstances, which it would bo premature to detail at present; such as the mode 
of life, the abundance and excess of food, the want of temperance, and other results 
of an imperfect and misdirected civilization. 
For the same reason, the relation which tho period of grow'th bears to the whole 
term of life, is not without many exceptions among tho domestic animals. On the 
one hand, they receive the influence of a superabundant nourishment, and on the other, 
are more frequently preserved from those excesses to which this abundance might 
have given rise. Hence, the duration of life is often prolonged among the domestic 
animals beyond the term already specified. 
The growth of the Horse being commonly completed in about four or five years, 
it lives twenty-five or even thirty-five, provided the natural term of its existence has 
not been sliortencd, as happens too frequently by ill treatment of every kind, by 
violent fatigues, as well as the want of attention and suitable nourishment. This 
animal presents, notwithstanding, several instances of remarkable longevity, and some 
individuals have been known to attain the advanced ages of sixty and even seventy 
years. 
As the Ass takes nearly as long as the Horse in reaching its full growth, the 
duration of its life ought to bo nearly the same ; yet it often breaks down before that 
period through injuries or neglect, which it receives most undeservedly from all 
quarters. It is observed that animals, naturally disposed to chastity, live longer 
than those of different propensities. The Mule and Bardeau are usually unable to 
procreate, and accordingly they live longer than either the Horse or Ass. Very fre- 
quently Mules die at the age of forty, and one has been known to attain the age of 
eighty years. 
The Bull takes about two or three years in growing, and the natural period of its 
life terminates at fifteen to twenty years. The Buffalo approaches the farmer very 
nearly in both of these respects ; yet it appears to take a little longer time in reach- 
ing its full growth, and hence lives to a more advanced age. The Sheep has nearly 
the same period of growth, and also a corresponding period of life. Tho Goat ap- 
proaches to the same terms, both in respect to its growth, and tho durafion of its 
existence; yet the extreme attachment of these two last-mentioned species to sexual 
propensities serves to abridge tho ordinary period of their lives, in those few cases 
where Man does not terminate their existence suddenly for his own advantage. 
The Hog being two years in attaining its full development, may reach the age of 
fifteen or twenty years, if not fattened before the term of puberty, as is most commonly 
done, though some old Boars have been known to pass far beyond the above-men- 
tioned terms. 
We may thus perceive that the relation of the period of growth to the duration of 
life does not remain constant among the domestic animals. It is, however, more 
precise with the wild I^Iammalia. Tlu* Lion lives twenty-five years according to 
Buffon, though several Lions of the Tower Menagerie of London lived in confine- 
ment to the extraordinary ages of sixty-three and seventy years, on tho authority of 
Shaw. The Mococo (/.emar catta) lives at least twenty year-*, llie Rabbit eight 
or nine ; the Haro seven ; the Mouse only a short time. The Elephant, it is said, 
lives for two hundred years; the Bear thirty ; and the Wolf fifteen or twenty. 
Further, the Dog usually lives fourteen years, though the lives of some individuals 
have been prolonged to twenty ; the Cat lives nine or ten years, and the Dromedary 
forty or fifty. 
. Nothing positive is known regtarding the ages to which the Seals and the Cetacea 
respectively attain ; it is, however, probable, from their near approximation to the 
Fishes, in external characters, that they resemble them also in the average duration 
of life ; in other words, they live to a very advanced age. This presumption is fur- 
ther confirmed with the Seals, by the fact that they take a very long time in growing. 
GENERAL REVIEW OF THE MAMMALIA CONTINUED. 
2Vie Structure of Teeth — their growth — the phenomena of successive dentition — 
their varieties of form. 
The teeth among the ^laramalia are always found upon the jaws or maxillary bones, 
which is far from being tho case with the lower classes of vertebrated animals the Rep- 
tiles and Fishes. Though useful auxiliaries of digestion, they are by no^ means essen- 
tial to that function ; for some animals are wholly destitute ot teeth, and in others, they 
are far removed both from the mouth and the intestinal canal. Their existence is no: 
exclusively proper to the vertebrated animals, nor are they always confined in them to 
the. bones of the mouth. 
The teeth of animals may be defined as bodies, generally bard or of a calcareous 
appearance, produced by the secretion of special organti, fortifying the onlerior parts 
of the alimentary canal, and by tho assistance of which, the greater part of these ani- 
mals seize, rctaiti, or divide the food with which they are nourished, while some em- 
ploy them further as weapons of offence and defence. The teeth of tlie Mammalia, 
