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That the bones might not interfere with motion, they are provided with hinges or ligaments.
That the ligaments might work smoothly into one another, the joints are separated by gristles or cartilages, and provided with a gland for the secretion of oil or mucus, which is constantly exuding into the joints.
478. There are 2448 separate boncs in the human body, classed under those of the head, the trunk, and the extremities.
The skull, or cranium, consists of eight pieces, and serves as a vault and protection to the brain, There are also the cheek-bones, the jaws, and 39 teeth imbedded in them,
The head is joined to the trunk by the vertebræ, consisting of several short bones, to the upper part of which it is fastened by a hingejoint, and turned in the socket of the next lower one by suitable muscles to the right or left.
479. In the front and centre of the trunk is the breast-bone, extending from the neck to the abdomen ; and opposite to it, in the back, is the spine or back-bone, which extends from the skull to the bottom of the loins, and is a long chain of separate short bones, called vertebræ,
These serve as the support of seven hoops or ribs, which are inserted in them, and form the chest or thorar, in which are the heart, lungs, &c.
Beneath them, inserted in the spine only, and extending but half way round the body, are tive
falar ribs, The lip bones, with other bonen at tsche, supporting the abdomen, are called the peloin,
460, From the neck to the top of each arm, A bone extends on eacli pide, called the collat bone, and the blade bones are independent sup porters of it. The bone extending froin the shoulder to the elbow is called the humerus,
Proin the elbow to the wrist are two bones, the outer of which is the radius; the imver the uina,
The thigh bone is called the femur; the kare, the patein; and the leg has two bones like the arm, the inner called the tibia, and the outer the fibula
411, The Animal Frame is constantly ex. bausted and renewed: so that every partiele of the human body is changed in the coming of a year!
Nor is it less surprising that so many different substances as compose every animal body, should also be secreted by the plunds from the sume blood, than that that blood mv, in every instance, be traced to giuss for its origin,
Ohe,--'lose functions by whicli aliment is assimilated for the nourisdiment of the body, ufe digration, aboni plion. circulation, respiration, and werelion i and the line of such dissimilation is called nutrition
2, --The food received into the stomach after mastica. tion by the terth, and bring mixed with suliwa, is (oth, verted into ehune lay the gastrie juiers the chyme pasks into the iuiratimes, where it is converted into chute and overementitious matter what to last, being partied toy mente of bile, in evarwater from the body tiist fe ehyla is absorbed by the tasteulo Aud conveyed into the blood vessels,
3. --The absorbent system consists of the lacteals, lymphatics, the thoracic duct, and the glands called conglobare throughout the body.
4.--Glands are organic bodies consisting of blood vese sels, nerves, and absorbents, intended for the secretion or alteration of particular fluids. They are divided into four classes, simple, compound, conglobate, and conglo. merate ; the orifices of glands are said to be peculiarly irritable.
5.--Secretion is the process by which various fluids are separated from the blood by means of the glands. The sccretions are divided into the saline, as sweat and urine ; the oleaginous as the fat, cerumen of the ear, &c. ; the sa ponaceous, as bile and milk; the mucous, as on the surface of membranes, &c.
6. Sensihility is the faculty of perception by the contact of an extrageous body; and this principle is generally didised in our corporeal organs, but in diferent degrées. That modification of animal matter, in which sensation appears peculiarly to exist, is termed nervous.
1.- Motion is effected by the muscular fibre contract. ing by volition ; but the will can only exercise this power, through the medium of the nerves. Irritability is the power of contraction, inherent in our bodily organs, but not liable to be inQuenced by the will.
482. All the senses of animals, and all their varied powers of action, are exactly adapted to their different species of existence. What is food for oue, is poison to another; and every one finds provision according to its natural habits,
Every thing, also, is in exact proportion; and every provision of nature harmonizes with the corresponding desires and wants of ammals.
Nature's unnumber'd family, combine
Coward, from those who tner in towie derinys.
PHAIT's lawer World 499. Linnarus divide, Animated Nature into,
1. QUADRUP 4,198 (Mummalia), of which were are already known to fou about 230 species.
2. BIRD, of which there are about 1,000 sprains.
%. AMPHIBIOU# ANIMALS, of which there are ntunut 100 xperies.
4. Fishes, of which there are about 500
6. IN CT4, of which there are 2,000 species.
And 6. Wotm#, of which there are 800 species
481. The firui class of animated beings, called mammalia, comprehend all those that suckle their youing: uit have watin red blood flowing in their arteries.
'lbrir bodies, for the mout part, are covered with hair, in quantity proportioned to the clue mate they inhabit. Beneath this covering, is a skin of various thicknen*, inclosing a franın or skeleton of irones, aried upon by a myotom of muscle anul condon, which are put in motion by nervos communicating with the organ of sense and the will of the animal.
They have Blood, for Life: Bonca, for Strength : Muscles, for Motion; and Neruri, for Sensatioa.
485. Linupus divides mammalious animals, or those which suckle thrir young, into seven orders ; which are' chictly regulated by the aunber and situation of the teeth.
a. Primates, or animals having iwo canine and four cutting teeth, and furnished with two pectoral teats. To this class belong man, the ape, the maucauco, and the bat.
Bruta, or animals which have no cutting the ant-eater, &c.
c. Fera, or animals whose cutting teeth vary from ten to two. This order includes most of the formidable rapacious quadrupeds ; as the lion, the tiger, the bear, &c.
d. Glires, or animals which have only two cutting and no canine teeth; as the hare kind, the mouse, the squirrel, &c.
e. Pecora, or aninials which are hoofed, and have no cutting teeth in the upper jaw, ix** ** cluding the camel, the deer, the sheep, the oxkinil, &c.
f. Belluæ, or quadrupeds with cutting teeth in each jaw, as the horse, the boar, &c.
g: Cetæ, or animals whose teeth greatly vary in different genera. This order comprehends all the whale tribes; which, from certain similarities of structure, are arranged under the class of quadrupeds,
436.' Birds, the second class, constitating those covered with feathers, have two wings to fly with, a tail to direct their flight, and a hard bony bill.' Their bones are hollow and light;