A Treatise on Physiology and Hygiene.

by Joseph Chrisman Hutchison.

PREFACE.

This work is designed to present the leading facts and principles of human Physiology and Hygiene in clear and concise language, so that pupils in schools and colleges, and readers not familiar with the subjects, may readily comprehend them. Anatomy, or a description of the structure of an organ, is of course necessary to the understanding of its Physiology, or its uses. Enough of the former study has, therefore, been introduced, to enable the pupil to enter intelligently upon the latter.

Familiar language, as far as practicable, has been employed, rather than that of a technical character. With a view, however, to supply what might seem to some a deficiency in this regard, a p.r.o.nouncing Glossary has been added, which will enable the inquirer to understand the meaning of many scientific terms not in common use.

In the preparation of the work the writer has carefully examined all the best material at his command, and freely used it; the special object being to have it abreast of the present knowledge on the subjects treated, as far as such is possible in a work so elementary as this. The discussion of disputed points has been avoided, it being manifestly inappropriate in a work of this kind.

Instruction in the rudiments of Physiology in schools does not necessitate the general practice of dissections, or of experiments upon animals. The most important subjects may be ill.u.s.trated by {4} drawings, such as are contained in this work. Models, especially those constructed by AUZOUX of Paris, dried preparations of the human body, and the organs of the lower animals, may also be used with advantage.

The writer desires to acknowledge his indebtedness to R. M. WYCKOFF, M.D., for valuable aid in the preparation of the ma.n.u.script for the press; and to R. CRESSON STILES, M.D., a skilful microscopist and physician, for the chapter "On the Use of the Microscope in the Study of Physiology." Mr. AVON C. BURNHAM, the well-known teacher of gymnastics, furnished the drawing of the parlor gymnasium and the directions for its use.

_Brooklyn, N. Y., 1870._

INTRODUCTION.

The Human Body is the abode of an immortal spirit, and is the most complete and perfect specimen of the Creator's handiwork. To examine its structure, to ascertain the uses and modes of action of its various parts, how to protect it from injury, and maintain it in a healthy condition, is the design of this work.

The departments of knowledge which are concerned in these investigations, are the science of Human Physiology and the art of Hygiene.

PHYSIOLOGY treats of the vital actions and uses of the various parts of living bodies, whether vegetable or animal. Every living thing, therefore, has a Physiology. We have a _Vegetable_ Physiology, which relates to plants; and an _Animal_ Physiology, relating to the animal kingdom. The latter is also divided into _Comparative_ Physiology, which treats of the inferior races of animals, and _Human_ Physiology, which teaches the uses of the various parts of the human body.

HYGIENE, or the art of preserving health, is the practical use of Physiology. It teaches us how to cultivate our bodily and mental powers, so as to increase our strength and to fit us for a higher enjoyment of life.

It also shows us how to prevent some of the accidents which may befall the body, and to avoid disease. It is proper that we should {12} understand the construction and powers of our bodies; but it is our duty, as rational beings, to know the laws by which health and strength may be maintained and disease warded off.

There are various means by which we gain important information respecting the Physiology of man. Plants aid us in understanding the minute structure of the human body, its circulation, and absorption. From inferior animals we learn much in respect to the workings of the different _organs_, as we call those parts of the system which have a particular duty to perform. In one of them, as in the foot of the frog, we can study the circulation of the blood; in another, we can study the action of the brain.

By _vivisection_, or the laying bare of some organ of a living animal, we are able to investigate certain vital processes which are too deeply hidden in the human body to be studied directly. This is not necessarily a cruel procedure, as we can, by the use of anaesthetics, so blunt the sensibility of the animal under operation, that he need not suffer while the experiment is being performed. There are other means by which we gather our information. There are occasionally men, who, from some accident, present certain parts, naturally out of view, in exposed positions. In these cases, our knowledge is of much greater value than when obtained from creatures lower in the scale of being than man.

We are greatly aided, also, by the use of various instruments of modern invention. Chief among these is the microscope, which is, as we shall learn hereafter, an arrangement and combination of lenses in such a way as greatly to magnify the objects we wish to examine. {13}

We have much to say of Life, or vital activity, in the course of our study of Physiology; but the most that we know of it is seen in its results. What Life is, or where its precise position is, we are not able to determine. We discover one thing, however, that all the parts of the body are united together with wonderful sympathy, so that one part cannot be injured and other parts not suffer damage. It is further evident that all organs are not equally important in carrying on the work of Life; for some may temporarily suspend their action, without serious results to the system, while others must never cease from acting. Yet there is nothing superfluous or without aim in our frames, and no part or organ can suffer harm without actual loss to the general bodily health. On this point Science and Holy Writ strictly agree.

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PHYSIOLOGY,

AND

HYGIENE.

CHAPTER I.

THE FRAMEWORK OF THE BODY.

_The Bones--Their Form and Composition--The Properties of Bone--The Skeleton--The Joints--The Spinal Column--The Growth of Bone--The Repair of Bone._

[Sidenote: 1. The framework of the body? The superstructure? Softness and delicacy of the organs? How protected?]

1. THE BONES.--The framework which sustains the human body is composed of the _Bones_. The superstructure consists of the various organs on which the processes of life depend. These organs are soft and delicately formed, and, if unprotected, would, in most cases, rapidly be destroyed when subjected to violence, however slight. The bones, having great strength and power of resistance, afford the protection required.

[Sidenote: 2. The more delicate the organ? Example in relation to the brain? The eye? The lungs? The services performed by the bones?]

2. The more delicate the organ, the more completely does Nature shield it.

For example: the brain, which is soft in structure, is enclosed on all sides by a complete box of bone; the eye, though it must be near the surface of the body to command an extensive view, is sheltered from injury within a deep recess of bone; the lungs, requiring freedom of motion as well as protection, are surrounded by a large case of bone and muscle. The bones serve other useful purposes. They give permanence of form to the body, by {16} holding the softer parts in their proper places. They a.s.sist in movement, by affording points of attachment to those organs which have power of motion--the muscles.

[Sidenote: 3. Their shape and size? Of what composed? Possibility of being separated? Effect of fire? Of dilute acid?]

3. THE FORM AND COMPOSITION OF THE BONES.--Their shape and size vary greatly in different parts of the body, but generally they are arranged in pairs, one bone for each side of the body. They are composed of both mineral and animal substances, united in the proportion of two parts of the former to one of the latter; and we may separate each of these substances from the other for examination. First, if we expose a bone to the action of fire, the animal substance is driven off, or "burned out." We now find that, though the shape of the bone is perfectly retained, what is left is no longer tough, and does not sustain weight as before. Again, we may remove the mineral portion, which is a form of lime, by placing a bone into a dilute acid. The lime will be dissolved out, and the shape of the bone remain as before; but now its firmness has disappeared, and it may be bent without breaking.

[Sidenote: 4. Effect of deficiency of ingredient? Usefulness of the lime?

Of the animal substance? Effect of their union? Condition, in youth? Old age?]

4. If, for any reason, either of these ingredients is disproportionate in the bone during life, the body is in danger. The lime is useful in giving rigidity of form, while the animal substance insures toughness and elasticity. By their union, we are able to withstand greater shocks and heavier falls than would be possible with either alone. In youth, the period of greatest activity, the animal const.i.tuent is in excess: a bone then does not break so readily, but, when broken, unites with great rapidity and strength. On the other hand, the bones of old persons are more easily broken, and in some cases fail to unite. The mineral matter being then in excess, indicates that the period of active exertion is drawing to a close.

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[Ill.u.s.tration: FIG. 1.--SECTION OF BONE.]

[Ill.u.s.tration: FIG. 2.

Structure of bone enlarged.]

[Sidenote: 5. In what respect admirably fashioned? Its formation?

Microscopic examination? The inference? "Line of beauty?"]

5. THE STRUCTURE OF THE BONES.--If we examine one of the long bones, which has been sawn through lengthwise, we observe that it is admirably fashioned for affording lightness as well as strength (Fig. 1). Its exterior is hard and resisting, but it is porous at the broad extremities, while through the central portion there is a cavity or ca.n.a.l which contains an oily substance, called _marrow_. Let us now take a thin section of bone, and examine it under the microscope; we discover that it is pierced by numerous fine tubes (Fig. 2), about which layers of bone-substance are arranged.

Accordingly, though a bone be as hard as stone externally, it is by no means as heavy as stone, by reason of its light interior texture. Another element of power is found in the curved outline of the bones. The curved line is said to be "the line of beauty," as it certainly is the line of strength, and is uniformly employed in the bones whose position exposes them to accident.

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[Ill.u.s.tration: FIG. 3.--THE SKELETON]