Hygienic Physiology | Page 3

or not, according to the judgment of the teacher.
NOTE.--Interest in the study of Physiology will be much increased by the use of the microscope and prepared slides. These may be obtained from any good optician.
INTRODUCTION.
Physiological study in youth is of inestimable value. Precious lives are frequently lost through ignorance. 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 lifelong 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 save or lengthen life, may repel or abate disease, and the simple laws which regulate our bodily vigor, should be so familiar that we may be quick to apply them in an emergency. The preservation of health is easier than the cure of disease. Childhood can not afford to 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 like. 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 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 life, but leaves the most for us to learn by bitter experience. So in youth we throw away our strength as if it were a burden of which we desire to be rid. We eat anything, and at any time; do anything we please, and sit up any number of nights with little or no sleep. Because we feel only a momentary discomfort from these physical sins, we fondly imagine when that is gone we are all right again. Our drafts upon our constitution are promptly paid, and we expect this will always be the case; but some day they will come back to us, protested; Nature will refuse to meet our demands, and we shall 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 all charged against this stock. Nature's memory never fails; she keeps her account with perfect exactness. 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 blazing throne, Nor yet alone on earth below, 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, Eternal wisdom still the same!"
HOLMES.
ANALYSIS OF THE SKELETON.
NOTE.--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 214 as given by Leidy and Draper. Gray omits the bones of the ear, and names 200 as the total number.
THE SKELETON. _ | I. THE HEAD (28 bones.) | _ | | Frontal Bone (forehead). | _ | Two Parietal Bones. | | 1. CRANIUM..............| Two Temporal (temple) Bones. | | (8 bones.) | Sphenoid Bone. | | | Ethmoid (sieve-like bone at root of nose). | | |_Occipital Bone (back and base of skull). | | _ | | | Two Superior Maxillary (upper jaw) Bones. | | | Inferior Maxillary (lower jaw) Bone. | | | Two Malar (cheek) Bones. | | 2. FACE.................| Two Lachrymal Bones. | | (14 bones.) | Two Turbinated (scroll like) Bones, each | | | side of nose. | | | Two Nasal Bones (Bridge of nose). | | | Vomer (the bone between the