CHAPTER XLVI.

Fig. 54.—VIEW OF THE BONES OF THE THORAX, OR CHEST, SHOWING THE PROTECTION AFFORDED TO THE ORGANS OF CIRCULATION AND RESPIRATION.

A. The sternum, or breast-bone.

B B. Theribs, which rise a little from behind, and fall as they come forward, by which they acquire a greater flexibility.

C C. Thecartilaginous pointsof the short ribs, by which their expansive and compressive powers are much increased.

D E. Part of the vertebral column, or back-bone.

931.Why are the bones of the skull divided by sutures (seams), with points which fit into each other like small teeth?

Because, by that arrangement,concussions of the skull, which might be fatal to the brain, aredeadened, and injuries from accidentgreatly modified.

"And I will lay the sinews upon you, and will bring up flesh upon you, and cover you with skin, and put breath in you, and ye shall live; and ye shall know that I am the Lord."—Ezekiel xxxvii.

932.Why are the heart, lungs, &c., placed within the chest?

Because the functions of those organs requireconsiderable space, while their importance in the system of life, renders it essential that they should besecurely protectedfrom the probabilities of accident.

933.Why are the heart and lungs enclosed for protection in a series of ribs, and not in a close case, like the brain?

Because, by the inflation and contraction of the lungs, theircapacity is constantly changing. When man takes a moderate inspiration, he inhales aboutthirty cubic inches of air, and the lungs increase in sizeone-eighteenth of their whole capacity. Consequently, were they enclosed in a frame offixed dimensions, it must needs be, to that extent at least, larger than is necessary, when the frame is made to dilate and contract with the capacity of the lungs.

So perfect is the Almighty contrivance, that not only are the ribs made toprotectthe lungs, but, by their elasticity, and the contractions and dilations of the muscles which lie between them, theyassist the lungs in their labours, and work with them in perfect harmony.

Fig. 55.—SECTION OF THE KNEE JOINT, SHOWING THE CELLULAR STRUCTURE OF BONE, BY WHICH LIGHTNESS AND STRENGTH ARE OBTAINED.

934.Why are the bones of the arms, legs, &c., made hollow?

Becauselightnessis thereby combined withstrength. There is a provision by which, in the extremities of bones, where an enlarged surface is required,lightnessis still combined with the necessary degree of strength.

The bones are made up of acellular formation; and this generally occurs in parts which are much called into action, in the various movements of the body.

A. Lower part of the bone of the thigh.

B. Head of the bone of the leg.

C. The knee cap, showing its relation to the other bones, and the manner in which it is enclosed by the tendons seen atFig. 58.

D. A pad of fat, lessening the friction of the bones, and modifying the shocks produced by jumping, &c.

"Again he said unto me, Prophesy upon these bones, and say unto them, O ye dry bones, hear the word of the Lord."—Ezekiel xxxvii.

935.Why are the bones of the arms and legs formed in long shafts?

Because a considerableleverageis gained, by which the advantages ofquickness of motion, andincrease of mechanical power, are secured.

936.Why are the bones of the hands and feet numerous and small?

Because the motions of the hands and feet are veryvaried and complicated. There are no less thantwenty-eight bonesin one hand and wrist; and aboutas manyin a foot and ankle. To these are fastened a great number ofligaments and muscles, by which their varied compound movements are controlled. But for the complexity of the mechanism of our hands and feet, our motions would be extremely awkward, and many of the valuable mechanical inventions which now benefit mankind, could never have been introduced. The bones of the hands and feet are in number equal toone-half of the whole of the bones of the body.

937.What are ligaments?

Ligaments consist of bands and cords of atough,fibrous,and smooth substance, by which the bones are bound together and held in their places, allowing them freedom to move, and supplying smooth surfaces over which they glide.

938.Why are the joints bound with ligaments?

Because the bones would otherwise be constantly liable toslip from their places.

"That which is born of the flesh is flesh; and that which is born of the Spirit is spirit."—John iii.

939.What are tendons?

Tendons arelong cords, of a substance similar in its nature tocartilage, by whichthe muscles are attached to the bones.

Fig. 56.—SHOWING A BALL AND SOCKET JOINT, AND THE MANNER IN WHICH LIGAMENTS ARE EMPLOYED TO HOLD BONES IN THEIR POSITIONS.

A. Theball, orheadof the thigh bone.

B. Thesocket, showing the ligament in the socket, which holds the head of the bone in its place, but allows it free motion.

C.Ligamentstied from bone to bone, giving firmness to the parts.

940.Why are tendons used to attach the muscles to the bones?

Because, by this arrangement, the large muscles by which the extremities are moved,may be placed at some distancefrom the bones upon which they act, and thus the extremities, instead of being large and clumsy, aresmallandneat.

941.How many muscles are there in the human body?

There are aboutfour hundred and forty-six musclesthat have been dissected and described, and the actions of which are perfectly understood. But there is probably a much larger number of muscles, and of compound actions of muscles, than the skill of man has been able to recognise.

"All flesh is not the same flesh: but there is one kind of flesh of men, another flesh of beasts, another of fishes, and another of birds."—Corinthians xvi.

Fig. 57.—ILLUSTRATION OF THE RELATION OF MUSCLES, TENDONS, AND BONES.

942.What is the constitution of a muscle?

Every muscle is made up of a number ofparallel fleshy fibres, or threads, which are bound together by a smooth and soft tissue, forming a sheath or case to the muscle, and enabling it toglide freelyover the surfaces upon which it moves.

A. Lower extremity of the muscle which draws the fore-arm towards the upper-arm, bends the elbow, raises the hand to the head, and is powerfully exerted in pulling, lifting, &c.

C. A muscle which gives off four longtendons, which pass under theligamentsof the wrist, one to each finger, and by which the fingers are bent upon the palm of the hand, as in grasping, &c.

F.Tendonof a muscle which draws the little finger and the thumb towards each other.

Theligamentsmay be seen enfolding the finger-joints, and also crossing the wrist, underneath thetendons.

The muscles are compressed intotendinous cordsat their ends, by which they areunited to the bones.

They are arranged inpairs, having reciprocal actions—each muscle havinga companion muscleby which the part which it moves is restored to its original position, when the influence of the first muscle is withdrawn, and the stimulus given to bring back the part.

943.Why can we raise our fingers?

Because muscles which lieon the fore-arm, and have theirtendons fastened at the ends of the fingers,contract, and by becoming shorter,draw the fingers upward, and towards the arm.

"Thou hast clothed me with skin and flesh, and hast fenced me with bones and sinews."—Job xi.

944.Why can we throw back the fingers after they have been raised?

Because the muscles at the back of the arm,whose tendons are attached to the back of the fingers, contract and restore them to their former position.

945.What degree of strength do the muscles possess?

The degree of strength of a muscle depends upon thehealthy conditionof the muscle, theamount of stimuluswhich it receives at the time of exertion, and the manner in whichits powers are applied.

The great muscle of the calf of the leg has been found, when removed from a dead body, to be capable of sustaining a weight equal toseven times the weight of the entire body.

But the contractile power of the living musclesis very great: the thigh bone has frequently been broken by muscular contractions in fits of epilepsy. And in cases where there has been a dislocation of the thigh, the head of the thigh-bone being thrown out of its socket, (Fig. 56) it has been found necessary to employ strong ropes, attached to a wheel turned by several hands, in order toovercome the contraction of the excited muscles, and to enable the operator to restore the bone to its place.

946.What is the stimulus which sets the muscles in action?

The muscles are excited to action bythe nerves, which they receive from thespinal cord.

947.Why does it require the influence of the will to set the arms in motion?

Because the muscles which form their mechanism arevoluntarymuscles—that is, they are subject to thewill of man, and influencedby impulses directed to them through the nervous systemby the mind, which is the governing power.

"And he took him by the right hand, and lifted him up; and immediately his feet and ankle bones received strength."—Acts iii.

948.Why does the heart beat without any effort of the will?

Because the muscles of the heart areinvoluntary muscles—that is, they areindependent of the will, and receivea continuous nervous stimuluswhich is notunder the controul of the mind.

Fig. 58.—MUSCLES AND VESSELS OF THE LEG AND FOOT.

A. A largeligament, which covers the knee pan, or moveable bone of the knee, by which the ends of the bones of the thigh and leg are kept from slipping over each other.

B. A muscle which passes underneath the cartilages of the ankle, and gives off fourtendons, which are distributed to the toes, and by which they are extended in elongating the foot, walking, &c.

C. Part of the muscle which forms the fleshy bulb of the calf of the leg, and which terminates in the largetendonattached to the heel, called thetendon of Achilles.

D. One of the ligaments which bind the tendons and the bones of the ankle.

E.Arteriesproceeding from the large vessel descending the leg, by which the toes are supplied.

949.Why are the muscles of the arms, &c., made subject to the controul of the will?

Because, as they supply the mechanism through which we adapt ourselves to our varying wants and circumstances, it was necessary that they should be placed under the controul of the mental power, and be movedonly in accordance with man's necessities.

"If thou sayest, Behold, we knew it not; doth not he that pondereth the heart consider it? and he that keepeth thy soul, doth not he know it? and shall not he render to every man according to his works?"—Proverbs xxiv.

950.Why are the motions of the heart, &c., made independent of the will?

Because, as the necessity for the heart's motion isfixed and unalterable, the constant motion of the heart could be best secured by giving it afixed nervous influence, by which it might be unfailingly prompted to fulfil its functions.

If the movements of man's heart weresubject to his will, he would be constantly required to regard the operations of that organ; and so large an amount of mental care and physical exertion would have to be employed in that direction, that man's sole work would be to keep himself alive. Hence we see the goodness of the Creator ingivinglife to man, and inkeeping the vital impulses under his divine care.

951.What are nerves?

The nerves are branches of thebrainand thespinal cord; they are distributed in great numbers to all the active and sensitive parts of the body.

952.What is the spinal cord?

The spinal cord is a long and large cord of nervous matter, which extends from the brain through a continuous tube formed by corresponding hollows in the bones of the back. It serves as a nervous trunkfor the distribution of nerves, just as the aorta distributes branches of blood-vessels.

953.Why is the spinal cord placed in the grooves formed by the back-bone?

Being a very vital part of the system, and from the delicacy of its structure liable to injuries, it is set in the back-bone forprotection; and so great is its security that it is only by force of an unusual kind that it can be injured.

"A sound heart is the life of the flesh: but envy is the rottenness of the bones."—Proverbs xiv.

954.How can branches proceed from it, if it is so securely encased in bone?

Because in the bones, on each side of the spinal cord, there aresmaller groovesfor the transmission of the nervous branches.

955.Of what does the nervous system consist?

Of thebrain, thespinal cord, and the branches which are callednerves.

Fig. 59.—SHOWING THE DISTRIBUTION OF NERVES AND VEINS, AND ILLUSTRATING THE MANNER IN WHICH THEY PASS THROUGH THE FLESH TO REACH THE PARTS TO WHICH THEIR FUNCTIONS BELONG.

A. B.Veinsof the fore-arm.

B. Canal formed in the muscle, through which atrunk-veinemerges.

C. Canal formed in the muscle, through which a largenerveemerges.

D. Canal through which aveinenters to communicate with the deep muscles of the arm.

956.What is the constitution of a nerve?

It consists of a thin membrane, or sheath, surroundinga greyish oily matter, which forms the nervous marrow. In the centre of this marrow is usually founda small fibre, which is supposed to be the essential part of the nerve; and most nerves consist of a number of these sheaths enclosing fibres running in parallel directions.

957.What is the nervous fluid?

The termnervous fluidis used to express our ideas of the mode by which the brain and spinal cord influence the remote parts: just as we say theelectric fluid, without knowing that such a fluid exists. It is the most convenient form of expression.

958.How many classes of nerves are there?

There are:—

1. The nerves ofmotion.2. The nerves ofsensation.3. The nerves ofspecial sense.4. The nerves ofsympathy.

"Having many things to write unto you, I would not write with paper and ink; but I trust to come unto you, and speak face to face, that our joy may be full."—II John.

959.What are the nerves of motion?

Thenerves of motionare those which, in obedience to the will,stimulate the muscles to act, and apportion the amount of stimulation they convey to the degree of exertion required.

Fig. 60.—MUSCLES OF THE HEAD AND FACE, WITH NERVES DISTRIBUTED THERETO.

A A A. Thefacial nerveemerging from underneath the ear, and distributing branches to the cheeks, temple, forehead, &c. This nerve excites the muscles of the face, and is chiefly instrumental in producing the expressions of the countenance under the changing emotions of the mind.

B B B.Musclesby which various motions are imparted to the head, face, mouth, &c., under thestimulus of the nerves.

960.What are the nerves of sensation?

Thenerves of sensationare those whichimpart a consciousness to the brainthat its commands to the nerves of motion have been obeyed, and how far they have been fulfilled.

"Oh that men would praise the Lord for his goodness, and for his wonderful works to the children of men."—Psalm cvii.

Let us perform a simple experiment, which will more clearly illustrate the phenomena ofmotionand ofsensation, which we are now describing, than a great deal of writing upon the subject. You hold in your hand this book: close it, and set it upon the table; lay your hands passively upon your lap, and thenwillyour hand, to take up the book, which is the same as to say,commandyour hand to take up the book. What occurs? The hand, immediately obeying your desire, stretches forward to the book, and takes hold of it. How do you know that you have hold of it? Youseethat you have: but were your eyes closed, you would be equally aware that the hand had reached the book, and fulfilled your wishes. It is by the nerves ofsensationthat you are made aware that the hand has fulfilled your instructions.

Consider what took place in the simple action. In the first instance, a desire arose in your mind to take up the book. Thebrainis the organ of the mind; and having branches either proceeding from itself, or from the spinal cord, to every part of the body—branches that traverse like telegraphic wires throughout every part of the system,—it transmitted instructions along the nerves that proceed to the muscles of the arm and hand, directing them to take up the book. This was done instantly; and as soon as it was done you became conscious that your will had been obeyed—becausethe nerves sent back a sensation to the brain acquainting it that the book had been taken up, and that at the moment of the dispatch it was in the firm hold of the hand.

In all the varied motions of the body this double action of the nerves takes place. It is obvious that without anoutwardimpulse from the brain, upon which the desire of the mind first made an impression, no motion of the muscles of the arm and the hand could have taken place; and it is also obvious that without aninwardimpulse from the nerves to the brain you would not have known that the muscles had fulfilled your instructions. The hand might have dropped by the side of the book, or have gone too far, or not far enough, and you would not have been aware of the result, but for an inward communication through the nerves.

We are not now speaking of the nerves which endow us with the sense offeeling, because they are regarded as separate and distinct from those nerves that produce in us consciousness of muscular response. When we walk, rise, or sit, we are made conscious, without any special feeling being exerted, that the muscles have placed the limb, or the body, in the desired position, that it is set down safely and firmly, and that we may repose upon it securely without further attention. We refer the impressions made by the book upon the nerves of the hand, and which enable us to tell whether it feels hot or cold, whether its surface is rough or smooth, and so on, to the special sense offeeling. The consciousness of muscular action is a separate and distinct function; and it is generally believed that the same nerves that convey the command of the will outward, bringing back the intimation that the will has been obeyed, but thatdifferent fibresof the nerves convey theoutwardand theinwardimpulses. A single nerve may therefore be likened to adouble wireconnected with the electric telegraph: one transmitting despatches in one direction, and the other in the opposite direction.

961.What are the nerves of special sense?

The nerves of special sense are those through which wehear,see,feel,smell, andtaste.

"For the Lord seeth not as man seeth; for man looketh on the outward appearance, but the Lord looketh on the heart."—Samuel xvi.

962.What are the nerves of sympathy?

The nerves of sympathy, or the system ofsympathetic nerves, are those which are distributed to theinternal organs, and which are independent of the will. They regulate the motions of the heart, the lungs, the stomach, &c., and stimulate the organs of secretion, so that those organswork in harmony with each other.

As the internal organs are all more or less dependent upon each other, and unite their functions for similar ends, it is obvious that there should prevail among them amutual consciousnessof their state. Otherwise, when the stomach had formed chyme, the liver might have no bile ready to fulfil its office; the absorbents might be in a state of rest at the moment when nutrition was set before them; and the heart might beat slowly, while the lungs were in active exertion to obtain additional blood to support an active exercise. The sympathetic system of nerves thereforeregulates and harmonises these internal functions.

963.Why do we see objects?

Because the light which is reflected from them enters our eyes and produces images of their forms upon a membrane of nerves called theretina, just as images are produced upon a mirror.

964.Why does this enable us to see?

Because the membrane which receives the images of objects is connected with theoptic nervewhich transmits to the brain impressions made by the reflections of light, just as other nerves convey the effects of feeling, hearing, tasting, &c.

965.Why are we enabled to move our eyes?

Because various muscles are so placed in relation to the eyeball, that their contraction draws the eye in the direction required. We are thus enabled to adjust the direction of the eye to the position of the objects we desire to see, in other words toset the mirror in such a position that it will receive the reflection. (See517.)

"Truly the light is sweet, and a pleasant thing it is for the eyes to behold the sun."—Ecclesiastes xi.

966.Why are we enabled to see large objects upon so small a surface?

Because the lenses and humours of the eyecollect the rays of lightcoming from every direction, and,bringing them into a focus, transmit them to the retina, where each ray impresses upon the nervous surface the qualities it received from the object which reflected it.

Fig. 61.—THE EYEBALL AND ITS MUSCLES.

A. Portion ofbonethrough which the optic nerve passes in its communication between the brain and the eye.

B. Theoptic nerve, from before which anexternal musclehas been cut away, leaving its two attachments.

C. Theglobeof the eye.

D. The muscle which turns the eyeoutward, and which is counteracted by a muscle on the other side.

E. The muscle which passes through a loop, or staple of cartilage I, andturns the eye obliquely. It is counteracted by a muscle situated underneath.

F. The muscle situated underneath, which turnsthe eyeball upwards, and is counteracted by

G. The muscle whichturns the eyeball downwards.

H. The muscle attached to a bone whichturns the eyeball upwards.

I. Thecartilaginous loopthrough which a muscle passes.

J. The front chamber of the eye filled with a clear fluid.

K. Fragment of the bone by which one of the muscles is fastened.

967.Why do some persons squint?

Because it sometimes happens that a muscle of the eyeacts too powerfullyfor its companion muscle, and draws the eye too much on one side.

968.Why does the pupil of the eye look black?

Because the pupil is anopeningthrough which the rays of light pass into the chamber of the eye. There is, therefore, nothing in the pupil, of the eye to reflect light.

"Keep me as the apple of thine eye; hide me under the shadow of thy wings."—Psalm xvii.

969.Why is the pupil of the eye larger sometimes than at others?

Because theiris, a ring of extremely fine muscles which surround the pupil, contracts when too much light falls upon the retina, and dilates when the light is feeble. It therefore enlarges or diminishes the size of the pupil toregulate the admission of light.

Fig. 62.—SECTION OF THE EYE SEEN FROM BEHIND.

A. Thepupilof the eye through which the light enters.

B. Theiris, which dilates or contracts, and thereby increases or lessens the size of thepupil.

C. The three coats of the eye, called thesclerotic,choroid, andretina.

D. Theciliary processes, or hair-like muscles, which have a slight vibratory motion which they impart to the fluids of the eye.

E. The dark coat of thechoroid, the coat forming theretinaremoved.

970.Why have we two eyes?

Because the field of vision is therebymuch extended; theintensityof sight is also increased, the impressions upon the brain being clearer and better defined, just as in astereoscopethe effect of vision is heightened by a double picture; the sense of sight being moreconstantlyexercised than any other sense during our waking moments,one eye is frequently called upon to give rest to the other; and the important faculty of vision, being endangered by the necessary exposure of some parts of the eye, and the equallynecessary delicacy of an organ formed to receive impressions from so ethereal an element as light, is rendered the more secure to us, since though one eye may become enfeebled, diseased, or wholly lost,the other eye will retain the blessing of sight.

"The eyes of the Lord are upon the righteous, and his ears are open unto their cry."—Psalm xxxiv.

971.Why, having two eyes, and each eye receiving a reflection upon its retina, does the brain experience only one impression of an object?

Because, besides those optical laws which bring upon the two retinas the exactly corresponding images of the same objects, the optic nervesmeetbefore they reach the brain,and blend the impulses which they convey.

972.Why are the eyes provided with eyelids?

Because the eyes require to bedefendedfrom floating particles in the air, and to be keptmoist and clean. The eyelids form the shutters of the eye, defending it when waking, by closing upon its surface whenever danger is apprehended, moistening its surface when it becomes dry, and covering it securely during the hours of sleep.

973.Why are the eyelids fringed with eyelashes?

Because the eyelashes assist to modify the light, and to protect the eye, without actually closing the eye-ids. When the eyelids are partially closed, as in very sunny or dusty weather, the eyelashes cross each other, forming a kind of shady lattice-work, from the interspaces of which the eye looks out with advantage, and sees sufficiently for the guidance of the body.

974.Why are we able to see at long or short distances?

Because thecrystalline lensof the eye is a moveable body, and is pushed forward, or drawn back by fine muscular fibres, according to the distances of the objects upon which we look. By these means itsfocusbecomes adjusted.

975.Why do we wink?

Because, by the repeated action of winking,the eye is kept moist and clean, and the watery fluid secreted by little glands in the eyelids, and at the sides of the eye, is spread equally over the surface, instead of being allowed to accumulate. But the action ofwinking, or brightening the eye, is so instantaneous that it does not impede the sight.

"And the eye cannot say unto the hand, I have no need of thee; nor again the head to the feet, I have no need of you."—Corinth. xii.

976.Whence are the humours and secretions of the eye derived?

From the blood, which flows abundantly to the eyes, and is circulated in capillary vessels that are spread out upon the membranous coats of the eye-balls.

Fig. 63.—SECTION OF THE EYE.

A and B. Thesclerotic,choroid, andretina, the three layers or coats which form the walls of the globe of the eye, and enclose its humours.

C C. Theiris.

D. The front chamber of the eye, filled with watery humour.

E. Thepupil, through which the rays of light pass to

F. Thecrystalline lens.

G G. Thevitreous humourenclosed in cells formed by thehyaloid membrane.

H. Anarterywhich supplies blood to thecrystalline lens, and which passes through the centre of theoptic nerve.

G. Theoptic nerve, showing the sheath in which the nerve is enclosed.

977.Why do tears form in the eyes?

Because, under the emotions of the mind, the circulation of blood in the brain, and in its nearest branches, becomes considerably quickened. The eyes receive a larger amount of blood, and the secretion of the lachrymal glands being increased, the fluid overflows, and tears are formed. The use of tears is probablyto keep the eyes cool during the excitement of the brain. They are formed also duringlaughing, but less frequently.

"If the whole body were an eye, where were hearing? if the whole were hearing, where were smelling?"—Corinthians xii.

978.Why do we feel inconvenienced by sudden light?

Because an excess of light enters the eye before theirishas hadtime to adjust the pupilto the amount of light to be received.

979.Why if we look upon a very bright light, and then turn away, are we unable to see?

Because theirishas so reduced the pupil while we were looking at the bright light, that immediately upon turning to a darker object,the pupil is too smallto admit sufficient rays to enable us to see.

Fig. 64.—CAPILLARY BLOOD-VESSELS OF THE EYE.

A A. Capillary veins distributed over thesclerotic coat.

B. One of the trunks of theoptic nerve.

C. Anervecommunicating with theciliary processes.

D. Aveinrunning parallel with the nerve to theciliary processes.

E. Side view of theiris.

980.Why do we see better after a short time?

Because theirishas relaxed and enlarged the pupil, thereforewe receive more rays of lightfrom the comparatively dark object, and are enabled to see it more clearly.

981.Why do cats, bats, owls, &c., see in the dark?

Because their eyes are made highly sensitive tosmall quantities of light. It is also believed that there are certain properties of light which affect their eyes, but do not affect ours. In other words,that there are some rays which are luminous to them which are not luminous to us. Hence they findlightin what we calldarkness.

"He that hath ears to hear, let him hear."—Matthew xi.

982.Why does the pupil of a cat's eye appear nearly closed by day?

Because the cat's eye is so sensitive to light that the iriscloses the pupil almost entirelyto shut out the too powerful light.

983.Why do we hear?

Because thetympanumof the earreceives impressions from sounds, and transmits those impressions to the brain in a similar manner to that in which the retina of the eye transmits the impressions made upon it by light.

984.Why is one part of the ear spread out externally?

The external ear is anatural ear-trumpet, and serves to collect the vibrations of sound, and to conduct them towards the internal ear.

985.Why is the ear allowed to project, whilst the eye is carefully enclosed?

Because the external ear, being formed of tough cartilaginous substance, and being very simple in its organisation, is but little liable to injury.

986.Why do hairs grow across the entrance of the ears?

Because they prevent the intrusion of insects, and of particles of dust, by which otherwise the faculty of hearing would be impaired.

The insect called theearwigis popularly supposed to be so named from its tendency to get into the human ear, and cause pain and madness by penetrating to the brain. An earwig, however, is no more likely to get into the ear than any other insect whose habit it is to penetrate the corollas of flowers; and should an insect enter the ear, it could get no further than themembrane of the tympanum, which spreads all over the auditory passage, just as the parchment of a drum spreads over the entire circumference of that instrument. The fact is, that the wing of the insect, when spread,resembles the external earin shape. It is similar to the wing of the stag beetle (seeillustration), and this fancied resemblance of the wing of the insect to the ear of man may have given rise to the name ofear-wing, which became corrupted toearwig.

"Doth not the ear try words? and the mouth taste his meat."—Job xii.

987.Why is wax secreted at the entrance of the ear?

Because, by the peculiar resinous property which it possesses,it improves the sound-conducting powerof the auditory canal through which it prevails.

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