n«)MmawpMMiiiK«3PMMu imiimim»nnniiHiitinimHiun»»»»m»tir;iHiHninmiiii ,frBDLB'S CI Em „/• ^ Cornell University Library The original of tliis book is in tine Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924084423981 CORNELL UNIVERSITY LIBRARY 924 084 423 981 PATHFINDER PHYSIOLOGY No. 3 Hygienic Physiology WITH SPECIAL REFERENCE TO THE USE OF ALCOHOLIC DRINKS AND NARCOTICS BEING A REVISED EDITION OF THE FOURTEEN WEEKS IN HUMAN PHYSIOLOGY JOB>L DoRiviAN Steele, Ph. ID. ENLARGED EDITION WITH SELECTED READINGS Edited for the use of Schools, in accordance with the recent Legislation upon Temperance Instruction NEW YORK • : • CINOINNATI • : • CHICAGO AIvlBRICAN BOOK COlVtPANV mDORSEMENT. Boston, J^ne 20, 1889. The Pathfinder Series of Text-Books on Anatomy, Physiology, md Hygiene consists of the following volumes : I. Child's Health Primer (for Primary Grades). II. Hygiene for Young People ; ) or, Young People's Physiology. ) ^^""^ intermediate Classes) III. Hygienic Physiology (for Advanced Pupils). The above are the series originally prepared (as their general itle indicates) to supply the demand created by the laws for temperance instruction in public schools in the United States. They were written by experts under the supervision of the Scien- tific Department of the National Woman's Christian Temperance Union, published by the instigation of the same, and have been carefully revised from time to time, under the same supervision, to keep them abreast with the latest teachings of science. Being both teachable and well adapted to grade, their educa- tional value, as proven by school-room tests, is of the highest order. We therefore cordially indorse and highly recommend the Pathfinder Series for use in schools. MARY H. HUNT, National and International Superintendent of the Scientific Dep't if the Woman's Christian Temperance Union; Life Director of the National Educational Association, ADVISORY BOARD: FosEPH C««ic W11.LIAM E. Sheldon, iiBBBT H. Funis, D.D. Daniel Dorchester, D.D. 0»9yHght, 1873, 18S1, and 1888, iy A. S. BABiras & Oo. Path. No. 3. .'=t^ 7=^^^^ The term Physiology, or the science of the functions of the body, has come to include Anatomy, or the science of its structure, and Hygiene, or the laws of health ; the one being essential to the proper understanding of physiology, and the other being its practical application to life. The three are intimately blended, and in treating of the different subjects the author has drawn no line of distinction where nature has made none. This work is not prepared for the use of medical students, but for the instruction of youth in the principles which underlie the preservation of health and the formation of correct physical habits. All else is made subservient to this practical knowledge. A simple scientific dress is used which, while conducing to clearness, also gratifies that general desire of children to know something of the nomenclature of any -study they' pursue. To the description of each organ is appended an account of its most common diseases, accidents, etc., and, when prac- ticable, their mode of treatment. A pupil may thus learn, for example, the cause nnd cure of "a cold," the management of a wound, or the nature of an inflammation. The Practical Questions, which have been a prominent feature in other books of the series, will be found, it is hoped. VI PREFACa. equally useful in this work. Directions for preparing simple microscopic objects, and illustrations of the difEerent organs, are given under each subject. The Headings, which represent the ideas but not always the exact phraseology of the author quoted, have, in general, been selected with direct reference to Practical Hygiene, a subject which now largely occupies the public mind. The dangers that lurk in foul air and contaminated water, in bad drainage, leaky gas-pipes, and defective plumbing, in reckless appetites, and in careless dissemination of contagious diseases, are here portrayed in such a manneiv, as, it is trusted, wiU assist the pupil to avoid these treacherous quicksands, and to provide for himself a solid path of health. Under the heading of Health and Disease will be found Hints about the sick-room. Directions for the use of Disinfect- ants, Suggestions as to what to do "Till the Doctor comes," and a Ust of antidotes for Poisons. Questions- for Class Use, a full Glossary, and an ample Index complete the book. Believing in a Divine Architect of the human form, the author can not refrain from occasionally pointing out His in- imitable workmanship, and impressing the lesson of a Great Final Cause. The author has gleaned from every field, at home and abroad, to secure that which would interest and profit his pupils. In general, Flint's great work on the " Physiology of Man," an undisputed authority on both sides of the Atlantic, has been adopted as the standard in digestion, respiration, cir- culation, and the nervous system. Leidy's "Human Anatomy," and Sappey's "Traits d'Anatomie" have been followed on all anatomical questions, and have furnished many beautiful draw- ings. Huxley's "Physiology" has afforded exceedingly valuable aid. Foster's "Text-Book of Physiology," Hinton's "Health and its Conditions." Black's "Ten Laws of Health," "Williams' PREFACE. Vll practical essay on "Our Eyes and How to Use them," Le Pileur's charming treatise on "The Wonders of the Human Body," and that quaint volume, "Odd Hoxirs of a Physician," have aided the author with facts and fancies. The writings of Draper, Dalton, Carpenter, Valentine, Mapother, Watson, Lan- kester, Letheby, Hall, Hamilton, Bell, Wilson, Bower, Cutter, Hutchison, Wood, Bigelow, Stille, Holmes, Beigel, and others have been freely consulted. PUBLISHERS' NOTE. An Abridged Edition of this work ia published, to afford a cheaper manual — adapted to Junior Classes and Common Schools, The abridgment contains the essence of this text, nearly all its illustrations, and the whole of the Temperance matter as here presented. Order "Hygienic Piysiology, Abridged." READiNQ References. FosTEB's "Text-Book of Physiology"; Leldy's "Human Anatomy", Draper's "Human Physiology"; Dalton's "Physiology and Hygiene"! Cutter's "Physiology"; Johnston and Church's "Chemistry of Common . Ufe"; Lethehy's "Pood"; Tyndall"On Light," and "On Sound"; Plint's " Physiology of Man " ; Eosenthal's " Physiology of the Muscles and Nerves " ; Bernstein's "Pive Senses of Man"; Huxley and Youmans' "Physiology and Hygiene"; Sappey's "Traite d'Anatomie"; Luys' "Brain and its Punctions"; Smith's "Poods"; Bain's "Mind and Body"; Pettigrew's "Animal Locomotion"; Carpenter's "Human Physiology," and "Mental Physiology"; Wilder and Gage's "Anatomy"; Jarvls' "Physiology and Laws of Health." Hargreaves' "Alcohol and Science"; Richardson's "Ten Lectures on Alcohol," and "Diseases of Modem Life"; Brown's "Alcohol"; Davis' "Intemperance and Crime"; Pitman's "Alcohol and the State"; "Anti- Tobacco"; Howie's "Stimulants and Narcotics"; Hunt's "Alcohol as Pood or Medicine"; Schutzenberger's " Fermentation " ; Hubbard's "Opium Habit and Alcoholism"; Trouessart's "Microbes, Psrments, and Molds." OlIAPTEB PA&-S INTRODUCTION xiii I.— THE SKELETON ...... 1. 269 The Head . ...... 9 The Trunk ....... 11 The Limbs ...... . . 15 II.— THE MUSCLES 25. 275 riL— THE SKIN . 47, 385 The Hair and the Nails .... 52 The Teeth 57 rV.— RESPIRATION AND THE VOICE . . 71, 297 v.— THE CIRCULATION ..... 101, 314 The Blood 105 The Heart ......... 110 The Arteries 114 The Veins .... ... 116 VI.— DIGESTION AND FOOD .... 149, 317 Vn.— THE NERVOUS SYSTEM .... 189, 330 The Brain . 193 The Spinal Cord and the Nerves . . . 197 The Sympathetic System 201 X OOKTBNIS. 3HAPTBK f AS! VIII.— THB SPECIAL SENSES .... 227. 345 Touch . 329 Taste 230 Smell 232 Hbabing . 234 Sight 236 EX.— HEALTH AND DISEASE.— DEATH AND DE- CAT 249 1. Hints About the Sick-hoom .... 255 2. Disinfectants 256 3. What to Do "Till the Doctoe Combs" . 257 4. Antidotes to Poisons . 265 X.— SELECTED EEADING-S ... . . 267 XL— APPENDIX 356 Questions fok Class Use 357 Glossaby ... 387 Indkx , , 395 Seeing is believing— more than that, it is often knowing and remembering. The mere reading of a statement is of little value compared with the observation of a fact. Every oppor- tunity should therefore be taken of exhibiting to the pupil the phenomena described, and thus making them real. A micro- scope is so essential to the understanding of many subjects, that it is indispensable to the proper teaching of Physiology. A suitable instrument and carefully prepared specimens, showing the structure of the bones, the skin, and the blood of various animals, the pigment ceUs of the eye, etc., may be obtained at a small cost from any good optician. On naming the subject of a paragraph, the pupil should be prepared to tell aU he knows about it. No failure should dis- courage the teacher in establishing this mode of study and reci- tation. A little practice will produce the most satisfactory results. The unexpected question and the apt reply develop a certain sharpness and readiness which are worthy of cultiva- tion. The questions for review, or any others that the wit of the teacher may suggest, can be effectively used to break the monotony of a topical recitation, thereby securing the benefits of both systems. Xn SUGGESTIONS TO TEAOHEBS. The pupil should expect to be questioned each day upon any subject passed over during the term, and thus the entire knowledge gained will be within his grasp for instant use. While some are reciting to the teacher, let others write on slates or on the blackboard. At the close of the recitation, let all criticise the ideas, the spelling, the use of capitals, the pro- nunciation, the grammar, and the mode of expression. Greater accuracy and much collateral drill may thus be secured at little expense of valuable school-time. The Introduction is designed merely to furnish suggestive material for the iirst lesson, preparatory to beginning the study. Other subjects for consideration may be found in the section on Health and Disease, in the Selected Readings, and among the questions given in the Appendix. Where time will allow, the Selected Readings may profitably be used in connec- tion with the topics to which they relate. Questions upon them are so incorporated with those upon the text proper that they may be employed or not, according to the judgment of the teachej. Note.— Interest In the study of Physiology wiU be much increased by the use of the microscope and prejared slides. These may be obtained from any good optician. INTRODUCTION. PETYSIOLOGICAL STUDY in youth is of inestimablb value. Precious lives are frequently lost through igno ranee. Thousands squander in early years the strength which should have been kept for the work of real life. -Habits are often formed in youth which entail weakness and poverty upon manhood, and are a cause of life-long regret. The use of a strained limb may permanently damage it. Some silly feat of strength may produce an irreparable injury A thoughtless hour of reading by twilight may impair the sight for life. A terrible accident may happen, and a dear friend perish before our eyes, while we stand by powerless to render the assistance we could so easily give did we " only know what to do." The thousand little hints which may sare or lengthen Ufe, may repel or abate disease, and the simple laws which regulate oiir bodily vigor, should be so familiar that we may be quick tc apply them in an emergency. The preservation of health is easier than the cure of disease. Childhood can not aflEord tc wait for the lesson of experience which is learned only when the penalty of violated law has been already incurred, and health irrevocably lost. Nature's Laws Inviolable.— In infancy, we learn how terribly Nature punishes a violation of certain laws, and how promptly she applies the penalty. We soon find out the peril of fire, falls, edged tools, and the Uke. We fail, however, to notice the equally sharp and certain punishments which bad habits entail. We are quick to feel the need of food, but not 25^1V INTRODUCTION. so ready to perceive the danger of an excess. A lack of air drives us at once to secure a supply ; foul air is as fatal, but it gives us no warning. Nature provides a little training for us at the outset of iife, but leaves the most for us to learn by bitter ezperience. So in youth we throw away our strength as if it were a burden of which we desire to be rid. We eat any thing, and at any time ; do any thing we please, and sit up any number of nights with little or no sleep. Because we feel only a momentary dis- comfort from these physical sins, we fondly imagine when that is gone we are all right again. Our drafts upon our constitu- tion are promptly paid, and we expect this will always be the case; but some day they will come back to us, protested; Kature will refuse to meet our demands, and we shaU find ourselves physical bankrupts. We are furnished in the beginning with a certain vital force upon which we may draw. We can be spendthrifts and waste it in youth, or be wise and so husband it till manhood. Our shortcomings are aU charged against this stock. Nature's memory never fails ; she keeps her account with perfect exact- ness. Every physical sin subtracts from the sum and strength of our years. We may cure a disease, but it never leaves us as it found us. We may heal a wound, but the scar still shows. We reap as we sow, and we may either gather in the thorns, one by one, to torment and destroy, or we may rejoice in the happy harvest of a hale old age. I. The Skeleton. ■' Not in. the "World of Light alone, "Where God has built His hlazing throne Nor yet alone on earth helow, "With belted seas that come and go, And endless isles of sunlit green Is all thy Maker's glory seen— Look in upon thy wondrous frame, Btemal -wisdom stiU. the same 1 " HOUSBS ANALYSIS OF THE SKELETON. o Eh NoTs.— The following Table of 206 bones is exclusive of the 8 sesamoid bones which occur in pairs at the roots of the thumb and great toe, making 814 as given by Leidy and Draper. Gray omits the bones of the ear, and names 200 as the total number. ■ Frontal Bone (forehead). Two Parietal Bones, Two Temporal (temple) Bones. Sphenoid Bone. Bthmoid (sieve-like bone at root of nose). Occipital Bone (back and base of sknll). Two Superior Maxillary (upper jaw) Bones. Inferior Maxillary (lower jaw) Bone. Two Malar (cheek) Bones. Two Lachrymal Bones. Two Turbinated (scroll Uke) Bones, each side of nose Two Nasal Bones (bridge of nose). Vomer (the bone between the nostrils). Two Palate Bones. 1. Cbaxium (8 bones.). 2. Faok (14 iones.) 3. Eabs. L (6 toms.) i Hammer. Anvil. Stirrup. gi HiBS . a i 1. Upmjr Libcbs. (Si bones.) 2, LOWBB LlHBB. (eo bones.) ( Cervical Vertebrae (seven vertebrae of the neck). :. ■< Dorsal Vertebrae (twelve vertebrae of the back). OPTNAL COLTnilN. i .L.v.at.i vcxbouio:; ^twelve vm'Leurte OI xne DaCi£ Lumbar Vertebrae (five vertebrae of the loins). True Eibs. False Eibs. STBiannff (breast-bone). Os HTomBS (bone at the root of tongue). ( Two Innominata. Pblvis J. Sacrum. I Coccyx. Shoulder \ Obmtcle. I Scapula. Ann J Humerus. I Vina ana Radius. j BUgkt Wrist or Carpal Bones Hand W Five Metacarpal Bones. ( Phaianges (i4 bones). ( Femur. Leg A Patella. ( TiUaandFUnOa. ( Seven Tarsal Bones. •■ Foot 4 Mve Metatarsal Bones. ( Phalanges {Ik banes). THE SKELETON. FOBH, STKnOTTJUK, Erc, or THE BOIOIB. OLASSTmOATIOK OF THB Boms. \ s. 1. Uses, 2. Composition. 8. Structure. 4. Growth. 5. Bepair, 6. The Joints. The Head. The Trunk. The Lhnbs. THE SKELETON. 1. FORM, STRUCTURE, ETC., OF THE BONES. (See page 269.) The Skeleton, or frame-work of the "House we live in," is composed of about 200 bones.* Uses and Forms of the Bones.— They have three principal uses: 1. To protect the delicate organs ;t 2. To serve as levers on which the muscles may act to produce motion ; and 3. To preserve the shape of the body. Bones differ in form according to the uses they subserve. For convenience in walking, some are long ; for strength and compactness,- some are short and thick; for covering a cavity, some are flat; and for special purposes, some are irregular. The gen- eral form is such as to combine strength and light- * The precise mimber varies in different periods of life. Several whioli ire separated in youth become united in old age. Thus five of the "false •vertebrae " at the base of the spine early join in one great bone— the sacrum ; while four tiny ones below it often run into a bony mass— the coccyx (Fig. 6) ; in the child, the sternum is composed of eight pieces, -while in the adult it consists of only three. While, however, the number of the bones is uncer- tain, their relative length is so exact that the length of the entire skeleton, and thence the height of the man, can he obtained by measuring a single one of the principal bones. Fossil bones and those found at Pompeii have the same proportion as our own. t An organ is a portion of the body designed for a particular use, called its fuTwSm.. Thus the heart circulates the blood ; the Kv»r produoes th« bile. THE SKELETON. CS, «. ness. For example, all the long bones of the limbs are round and hoUow, thus giving with the same weight a greater strength,* and also a larger surface for the attachment of the muscles. The Composition of the Bones at maturity is about one part animal to two parts mineral matter. The proportion varies with the age. In youth it is nearly half and half, while in old age the mineral is greatly in excess. By soaking a bone in weak muri- atic acid, and thus dissolving the mineral matter, its shape will not change, but its stiffness will disap- pear, leaving a tough, gristly substance f (cartilage) which can be bent like rubber. If the bone be burned in the fire, thus consuming the animal matter, the shape will still be the same, but it will have lost its tenacity, and the beautiful' • Cut a sheet of foolscap in two pieces. EoU one half into a, compact oyUnder, and fold the other into a close, flat strip ; support the enda of each and hang weights in the middle until they bend. The superior strength of the roll will astonish one unfamiliar with this mechanical principle In a rod, the particles break in succession, first those on the outside and later those in the center. In a tube, the particles are aU arranged where they resist the first strain. Iron plUars are therefore cast hoUow. Stalks of ^ass and grain are so light as to bend before a breath of wind, yet are Btifl enough to sustain their load of seed. Bone has been found by experi- ment to possess twice the resisting property of soHd oak. t Mix a wine-glass of muriatic acid with a pint of water, and place in It a sheep s rib. In a day or two, the bone will become so soft that it can be tied mto a knot, m the same way, an egg may be made so pliable that It can be crowded into a narrow-necked bottle, within which it will expand and become an object of great curiosity to the uninitiated. By boiling bones at a high temperature, the animal matter separates in the form of gelatine. Dogs and cats extract the animal matter from the bones they eat. B'oasil bones deposited in the ground during the Gecaoglc period, were found by Ouvier to contain considerable animal matter. Gelatine was aotuaJly extracted from the Cambridge maatodon, and made into glue A tolerably nutritious food raigbt thus be manufactured from bones older than man himself. 8.7.) THE COMPOSITION OF THE BONES. PiQ. 2. Bl* piire--white residue* may be crumbled into powder with the fingers. We thus see that a bone receives hardness and rigidity from its mineral, and tenacity and elasticity from its animal m.atter. The entire bone is at first composed of cartilage, which gradually ossifies or turns to bone.f Certain portions near the joints are long delayed in this process, and by their elasticity assist in breaking the shock of a falLJ Hence • Itam 'bones thus caloiiied, the phosphorus of the chemist is made. See Steele's " Popular Chemistry," page 114. If the animal matter be not consumed, but only charred, the bone will be black and brittle. In this way, the " bone-black " of commerce is manufactured. t The oBsiflcation of the bones on the sides and upper part of the skull, for example, begins by a rounded spot in the middle of each one. I'rom this spot the ossi- fication extends outward in every direction, thus gradu- ally approaching the edges of the bone. When two adjacent bones meet, there will be a line where their edges are in contact with each other, but have not yet united; but when more than two bones meet in this way, there will be an empty space between them at their point of junction. Thus, if you lay down three coins upon the table with their edges touching one an- other, there wiU be a three-sided space in the middle between them ; iC you lay down four coins in the same manner, the space between them will be four-sided. Now at the ba and seize." Banes of the right Fore-arm. H, tlie humerus : B, the radius ; and TJ, the ulna. 18, 19.] THE HAND. 17 PiQ. 12. only two directions, i. e., backward and forward. The ulna is small at its lower end ; the radius, or ■ large bone of the fore-arm, on the contrary, is small at its upper end, while it is large at its lower end, where it forms the wrist- joint. At the elbow, the head of the radius is convex and fits into a shallow cavity in the ulna, while at the wrist the ulna plays in a similar socket in the radius. Thus the radius may roll over and even cross the ulna. The Wrist, or carpus, consists of two rows of very irregular bones, one of which articulates with the fore-arm ; the other, with the hand. They are placed side to side, and so firmly fastened as to admit of only a gliding motion. This gives little play, but greab strength, elasticity, and power of resisting shocks. The Hand.— The meton carpal {meta, beyond; kar- pos, wrist), or bones of the palm, support each a thumb or a finger. Each finger has three bones, while the thumb has only two. The first bone of the thumb, stand- ing apart from the rest, enjoys a special freedom of motion, and adds greatly to the usefulness of the hand. The first bone (Figs. 11, 12) of each finger is so Bonee of the Band and the Wnat. 18 THE SKELETON. [18,20. attached to the corresponding metacarpal bone as to move in several directions upon it, but the other phalanges form hinge-joints. The fingers are named in order: the thumb, the index, the middle, the ring, and the httle finger. Their different lengths cause thein to fit the hollow of the hand when it is closed, and probably enable us more easily to grasp objects of varying size. If the hand clasps a ball, the tips of the fingers will be in a straight line. The hand in its perfection belongs only to man. Its elegance of outline, delicacy of mold, and beauty of color have made it the study of artists ; while its exquisite mobility and adaptation as a perfect instru- ment have led many philosophers to attribute man's superiority even naore to the hand than to the mind.* 2. The Lower Limbs.— The Hip.— The thigh-bone, or femur, is the largest and necessarily the strongest in the skeleton, since at every step it has to bear * How constantly the hand aids us in explaining or enforcing a thought 1 We afflrm a fact by placing the hand as if we would rest it flrmly on a hody ; we deny hy a gesture putting the false or erroneous proposition away from us; we express douht by holding the hand sus- pended, as if hesitating whether to take or reject. When we part from dear friends, or greet them again after long ahsenoe, the hand extends toward them as IC to retain, or to bring them sooner to us. If a recital or a proposition is revolting, we reject it energetically in gesture as in thought. In a friendly adieu we wave our good wishes to him who is their object; but when it expresses enmity, by a brusque movement we sever every tie. The open hand is carried backward to express fear or horror, as well as to avoid contact ; it goes forward to meet the hand of friendship ; it is raised suppliantly in prayer toward Him from whom we hope for help ; it ca- resses lovingly the downy cheek of the infant, and rests on its head in- voking the blessing of Heaven.— ffomie™ of the Human Body. 20, 21.1 THE HIP. 19 the -weight of the whole body. It articulates with the hip-bone by a ball-and-socket joint. Unlike the shoulder-joint, the cup here is deep, thus affording Fig. 13. The Mechanism of the Bipjoint. less play, but greater strength. It fits so tightly that the pressure of the air largely aids in keeping the bones in place.* Indeed, when the muscles are cut away, great force is required to detach the limbs. The Knee is strengthened by the patella, or knee- ♦ In order to test tliis, a hole was bored through a hip-hone, so as to admit air into the socket ; the thigh-bone at once fell out as far as the ligaments "woTild permit. An experiment waa also devised whereby a suit- ably-prepared hip-joint was placed under the receiver of an air-pmnp. On exhausting' the air, the weight of the femur caused it to drop out of the socket, while the re-admission of the air raised it to its place. Without this arrangement, the adjacent muscles would have been compelled to bear the additional weight of the thigh-bone every time it was raised. Now the pressure of the air rids them of this unnecessary burden, and hence they are less easily fatigued.— Weber. 20 THE SKELETON. [81,22. pan {patella, little dish), a chestnut-shaped bone firmly fastened over the joint. The shin-bone, or tibia, the large, triangular bone on the inner side of the leg, articulates both with the femur and the foot by hinge-joints. The knee-joint is so made, however, as to admit of a slight rotary motion when the limb is not extended. The fibula (fibula, a clasp), the small, outside bone of the leg, is firmly bound at each end to the tibia. (See Fig. 1.) It is immovable, and, as the tibia bears the principal weight of the body, the chief use of this second bone seems to be to give more surface to which the muscles may be attached.* The Foot.— The general arrangement of the foot is strikingly like that of the hand (Fig. 1). The several parts are the tarsus, the metatarsus, and the pha- langes. The graceful arch of the foot, and the nu- merous bones joined by cartilages, give an elasticity to the step that could never be attained by a single, flat bone.f The toes naturally lie straight forward in the line of the foot. Few persons in civilized nar tions, however, have naturally-formed feet. The big toe is crowded upon the others, while crossed toes, nails grown-in, enormous joints, corns, and bunions abound. * A yotmg man in the hospital at Limoges had lost the middle part of his tibia. The lost hone -was not reproduced, hnt the flbnla, the naturally- weak and slender part of the leg, became thick and strong enough to sup- port the whole body.— Staklbt's Lectures. t The foot consists of an arch, the base of which is more extended in front than behind, and the whole weight of the body is made to fall on this arch by means of a variety of joints. These joints further enable the foot to be applied, without inconvenience, to rough and uneven surfaces.— Hinton. 22, 23.J THE FOOT. 21 The Cause of these Deformities is found in the shape and size of fashionable boots and shoes. The sole ought to be large enough for full play of mo- tion, the uppers should not crowd the toes, and the heels should be low, flat, and broad. As it is, there is a constant warfare between Nature and our shoe- makers,* and we are the victiixis. The narrow point in front pinches our toes, and compels them to over- ride one another; the narrow sole compresses the arch; while the high heel, by throwing all the weight forward on the toes, strains the ankle, and, by sending the pressure where Nature did not design it to fall, causes that joint to become enlarged. The body bends forward to meet the demand of this new motion, and thus loses its uprightness and beauty, making our gait stiff and ungraceful. (See p. 271.) Diseases, etc. — 1. Rickets, a disease of early life, is caused by a lack of mineral matter in the bones, rendering them soft and pliable, so that they bend under the weight of the body. They thus become permanently distorted, and of course are weaker than if they were straight, f Rickets is most common among children who have inherited a feeble constitu- * When we are measiired for boots or shoes, we should stand on a sheet of paper, and have the shoemaker mark with a pencil the exact outline of our feet as they bear oar whole weight. When the shoe is made, the sole should exactly cover this outline. + Just here appears an exceedingly beautiful provision. As soon as the disproportion of animal matter ceases, a larger supply of mineral is sent to the weak points, and the bones actually become thicker, denser, harder, and consequently stronger at the very concave part where the stress of pressure is greatest.— Watson's Lectures. We shall often have occasion to refer to similar wise and providential arrangements whereby the body is enabled to remedy defects, and to prepare for accidents. [23. 22 THE SKELETON. tion and who are ill fed, or who live in damp, unventi- lated houses. "Rickety" children should have plenty of fresh air and sunhght, nourishing food, comfortable clothing, and, in short, the best of hygienic care. 2. A Felon is a swelling of the finger or thumb, usually of the last joint. It is marked by an accu- mulation beneath the periosteum and next the bone. The physician, will merely cut through the perios- teum, and let out the effete matter. 3. Bow-legs are caused by children standing on their feet before the bones of the lower limbs are strong enough to bear their weight. The custom of encouraging young children to stand by means of a chair or the support of the hand, while the bones are yet soft and phable, is a cruel one, and liable to produce permanent deformity. Nature will set the child on its feet when the proper time comes. 4. Curvature of the Spine.— When the spine is bent, the packing between the vertebra becomes compressed on one side into a wedge-like shape. After a time, it will lose its elasticity, and the spine will become distorted. This often occurs in the case of students who bend forward to bring their eyes nearer their books, instead of lifting their books nearer their eyes, or who raise their right shoulder above their left when writing at a desk which is too high. Round shoulders, small, weak lungs, and, frequently, diseases of the spine are the consequences. An erect posture in reading or writing conduces not alone to beauty of form, but also to health of body. We shall learn hereafter that the action of the 23,84.J DISJBASBS, ETC. 23 muscles bears an important part in preserving the symmetry of the spine. Muscular strength comes from, bodily activity ; hence, one of the best pre- ventives of spinal curvature is daily exercise in the open air. 5. Sprains are produced when the ligaments ■which bind the bones of a joint are strained, twisted, oi torn from their attachments. They are quite as serious as a broken bone, and require careful atten- tion lest they lead to a crippling for life. By pre- mature iise a sprained limb may be permanently impaired. Hence, the joint should be kept quieti even after the immediate pain is gone. 6. A Dislocation is the forcible displacement of a bone from its socket. It is, generally, the result of a fall or a violent blow. The tissues of the joint are often ruptured, while the contraction of the muscles prevents the easy return of the bone to its place. A dislocation should be reduced as soon as possible after the injury, before inflammation super- venes. PRACTICAL QUESTIONS. 1. Why does not a fall Imrt a child as much as it does a grown perso? , 2. Should a young child ever be urged to stand or walk f 3. What is meant by " breaking one's neck " ? 4. Should chairs or benches have straight backs? 5. Should a child's feet be allowed to dangle from a high seatf 6. Why can we tell whether a fowl is young by pressing on the >jint of the breast-bone? 7. What is the use of the marrow In the bones? 8. Why is the shoulder so often put out of joint*