Part 20

In 1667 Elizabeth Tuttle, "of strong will, and of extreme intellectual vigor, married Richard Edwards of Hartford, Conn., a man of high repute and great erudition. From their one son descended another son, Jonathan Edwards, a noted divine, and president of Princeton College. Of the descendants of Jonathan Edwards much has been written; a brief catalogue must suffice: Jonathan Edwards, Jr., president of Union College; Timothy Dwight, president of Yale; Sereno Edwards Dwight, president of Hamilton College; Theodore Dwight Woolsey, for twenty-five years president of Yale College; Sarah, wife of Tapping Reeve, founder of Litchfield Law School, herself no mean lawyer; Daniel Tyler, a general in the Civil War and founder of the iron industries of North Alabama; Timothy Dwight, second, president of Yale University from 1886 to 1898; Theodore William Dwight, founder and for thirty-three years warden of Columbia Law School; Henrietta Frances, wife of Eli Whitney, inventor of the cotton gin, who, burning the midnight oil by the side of her ingenious husband, helped him to his enduring fame; Merrill Edwards Gates, president of Amherst College; Catherine Maria Sedgwick of graceful pen; Charles Sedgwick Minot, authority on biology and embryology in the Harvard Medical School; Edith Kermit Carow, wife of Theodore Roosevelt; and Winston Churchill, the author of _Coniston_ and other well-known novels."

Of the daughters of Elizabeth Tuttle distinguished descendants also came. Robert Treat Paine, signer of the Declaration of Independence; Chief Justice of the United States Morrison R. Waite; Ulysses S. Grant and Grover Cleveland, presidents of the United States. These and many other prominent men and women can trace the characters which enabled them to occupy the positions of culture and learning they held back to Elizabeth Tuttle.

Euthenics.--Euthenics, the betterment of the environment, is another important factor in the production of a stronger race. The strongest physical characteristics may be ruined if the surroundings are unwholesome and unsanitary. The slums of a city are "at once symptom, effect, and cause of evil." A city which allows foul tenements, narrow streets, and crowded slums to exist will spend too much for police protection, for charity, and for hospitals.

Every improvement in surroundings means improvement of the chances of survival of the race. In the spring of 1913 the health department and street-cleaning department of the city of New York cooperated to bring about a "clean up" of all filth, dirt, and rubbish from the houses, streets, and vacant lots in that city. During the summer of 1913 the health department reported a smaller percentage of deaths of babies than ever before. We must draw our own conclusions. Clean streets and houses, clean milk and pure water, sanitary housing, and careful medical inspection all do their part in maintaining a low rate of illness and death, thus reacting upon the health of the citizens of the future. It will be the purpose of the following pages to show how we may best care for our own bodies and how we may better the environment in which we are placed.

REFERENCE BOOKS

ELEMENTARY

Hunter, _Laboratory Problems in Civic Biology_. American Book Company. Bailey, _Plant Breeding_. Macmillan and Company. Harwood, _New Creations in Plant Life_. The Macmillan Company. Jordan, _The Heredity of Richard Roe_. American Unitarian Association. Sharpe, _Laboratory Manual_, pp. 64-72, 345-347. American Book Company.

ADVANCED

Allen, _Civics and Health_. Ginn and Company. Coulter, Castle, East, Tower, and Davenport, _Heredity and Eugenics_. University of Chicago Press. Davenport, _Heredity in Relation to Eugenics_. Henry Holt and Company. De Vries, _Plant Breeding_. Open Court Publishing Company. Goddard, _The Kallikak Family_. The Macmillan Company. Kellicott, _The Social Direction of Human Evolution_. Appleton Company. Punnet, _Mendelism_. The Macmillan Company. Richards, Helen M., _Euthenics, the Science of Controllable Environment_. Walter, _Genetics_. The Macmillan Company.

XVIII. THE HUMAN MACHINE AND ITS NEEDS

_Problem.--To obtain a general understanding of the parts and uses of the bodily machine._

LABORATORY SUGGESTIONS

_Demonstration._--Review to show that the human body is a complex of cells. _Laboratory demonstration_ by means of (_a_) human skeleton and (_b_) manikin to show the position and gross structure of the chief organs of man.

Man and his Environment.--In the last chapter we saw that one factor in the improvement of man lies in giving him better surroundings. It will be the purpose of the following chapters to show how man is fitted to live in the environment in which he is placed. He comes in contact with air, light, water, soil, food, and shelter which make his somewhat artificial environment; he must adapt himself to get the best he can out of this environment.

The Needs of Living Things.--We have already found that the primary needs of plants and animals are the same. They both need food, they both need to digest their food and to have it circulate in a fluid form to the cells where it will be used. They both need oxygen so as to release the energy locked up in their food. And they both need to reproduce so that their kind may be continued on the earth. What is true of plants and other animals is true of man.

The Needs of Simple and Complex Animals the Same.--The simplest animal, a single cell, has the same needs as the most complex. The _cell_ paramoecium feeds, digests, oxidizes its food, and releases energy. The _cells_ of the human body built up into tissues have the same needs and perform the same functions as the paramoecium. It is the _cells_ of the body working together in groups as tissues and organs that make the complicated actions of man possible. Division of labor has arisen because of the complex needs and work of the organism.

The Human Body a Machine.--In all animals, and the human animal is no exception, the body has been likened to a machine in that it turns over the _latent_ or potential energy stored up in food into _kinetic_ energy (mechanical work and heat), which is manifested when we perform work. One great difference exists between an engine and the human body. The engine uses fuel unlike the substance out of which it is made. The human body, on the other hand, uses for fuel the same substances out of which it is formed; it may, indeed, use part of its own substance for food. It must as well do more than purely mechanical work. The human organism must be so delicately adjusted to its surroundings that it will react in a ready manner to stimuli from without; it must be able to utilize its fuel (food) in the most economical manner; it must be fitted with machinery for transforming the energy received from food into various kinds of work; it must properly provide the machine with oxygen so that the fuel will be oxidized, and the products of oxidation must be carried away, as well as other waste materials which might harm the effectiveness of the machine. Most important of all, the human machine must be able to repair itself.

In order to understand better this complicated machine, the human body, let us briefly examine the structure of its parts and thus get a better idea of the interrelation of these parts and of their functions.

The Skin.--Covering the body is a protective structure called the skin. Covered on the outside with dead cells, yet it is provided with delicate sense organs, which give us perception of touch, taste, smell, pressure, and temperature. It also aids in getting wastes out of the body by means of its sweat glands and plays an important part in equalizing the temperature of the body.

Bones and Muscles.--The body is built around a framework of bones. These bones, which are bound together by tough _ligaments_, fall naturally into two great groups, the bones of the body proper, vertebral column, ribs, breast bone, and skull, which form the _axial_ skeleton, and the appendages, two sets of bones which form the framework of the arms and legs, which with the bones which attach them to the axial skeleton form the _appendicular_ skeleton.

To the bones are attached the muscles of the body. Movement is accomplished by contraction of muscles, which are attached so as to cause the bones to act as levers. Bones also protect the nervous system and other delicate organs. They also help to give form and rigidity to the body.

Hygiene of Muscles and Bones.--Young people especially need to know how to prevent certain defects which are largely the result of bad habits of posture. Standing erect is an example of a good habit, round shoulders a bad habit of this sort. The habit of a wrong position of bones and muscles once formed is very hard to correct. This can best be done by certain corrective exercises at home or in the gymnasium.

Round shoulders is most common among people whose occupation causes them to stoop. Drawing, writing, and a wrong position when at one's desk are among the causes. Exercises which strengthen the back muscles and cause the head to be kept erect are helpful in forming the habit of erect carriage.

Slight curvature of the spine either backward or forward is helped most by exercises which tend to straighten the body, such as stretching up with the hands above the head. Lateral curvature of the spine, too often caused by a "hunched-up" position at the school desk, may also be corrected by exercises which tend to lengthen the spinal column.

It is the duty of every girl and boy to have good posture and erect carriage, not only because of the better state of health which comes with it, but also because one's self-respect demands that each one of us makes the best of the gifts that nature has given us. An erect head, straight shoulders, and elastic carriage go far toward making their owner both liked and respected.

Other Body Structures.--In spaces between the muscles are found various other structures,--blood vessels, which carry blood to and from the great pumping station, the heart, and thence to all parts of the body; connective tissue, which holds groups of muscle or other cells together; fat cells, scattered in various parts of the body; various gland cells, which manufacture enzymes; and the cells of the nervous system, which aid in directing the body parts.

Body Cavity.--Within the body is a cavity, which in life is almost completely filled with various organs. A thin wall of muscle called the _diaphragm_ divides the body cavity into two unequal spaces. In the upper space are found the _heart_ and _lungs_, in the lower, the digestive tract with its glands, the _liver_, _kidneys_, and other structures (see page 267).

Digestion, Absorption, and Excretion.--Running through the body is a food tube in which undigested food is placed and from which digested or liquid food is absorbed into the blood so that the cells of the various organs which do the work may receive food. Emptying into this food tube are various groups of gland cells, which pour digestive fluids over the solid foods, thus aiding in changing them to liquids. Solid wastes are passed out through the posterior end of the food tube, while liquid wastes are excreted by means of glands called _kidneys_.

Work done by Cells.--Food, prepared in the digestive tract, and oxygen from the lungs are taken by the blood to the cells. Bathed in liquid food, the cells do their work; they promote the oxidization of food and the exchange of carbon dioxide for oxygen in the blood, while other wastes of the cells are given off, to pass eventually through the kidneys and out of the body.

The Nervous System.--The smooth working of the bodily machine is due to another set of structures which direct the working of the parts so that they will act in unison. This director is the nervous system. We have seen that, in the simplest of animals, one cell performs the functions necessary to its existence. In the more complex animals, where groups of cells form tissues, each having a different function, a nervous system is developed. _The functions of the human nervous system are:_ (1) _the providing of man with sensation, by means of which he gets in touch with the world about him;_ (2) _the connecting of organs in different parts of the body so that they act as a united and harmonious whole;_ (3) _the giving to the human being a will, a provision for thought._ Cooperation in word and deed is the end attained. We are all familiar with examples of the cooperation of organs. You see food; the thought comes that it is good to eat; you reach out, take it, raise it to the mouth; the jaws move in response to your will; the food is chewed and swallowed. While digestion and absorption of the food are taking place, the nervous system is still in control. The nervous system also regulates pumping of blood over the body, respiration, secretion of glands, and, indeed, every bodily function. Man is the highest of all animals because of the extreme development of the nervous system. Man is the thinking animal, and as such is master of the earth.

REFERENCE READING FOR THIS AND SUCCEEDING CHAPTERS ON HUMAN BIOLOGY

ELEMENTARY

Hunter, _Laboratory Problems in Civic Biology_. American Book Company. Davison, _The Human Body and Health_. American Book Company. Gulick, _The Gulick Hygiene Series_. Ginn and Company. Overton, _General Hygiene_. American Book Company. Ritchie, _Human Physiology_. World Book Company. Sharpe, _Laboratory Manual in Botany_, pages 218-225. American Book Company.

ADVANCED

Halliburton, _Kirk's Handbook of Physiology_. P. Blakiston's Son and Company. Hough and Sedgwick, _The Human Mechanism_. Ginn and Company. Howell, _Physiology_, 3d edition. W. B. Saunders Company. Schafer, _Textbook of Physiology_. The Macmillan Company. Stiles, _Nutritional Physiology_. W. B. Saunders Company. Verworn, _General Physiology_. The Macmillan Company.

XIX. FOODS AND DIETARIES

_Problems.--A study of foods to determine:--_ _(a) Their nutritive value._ _(b) The relation of work, environment, age, sex, and digestibility of foods to diet._ _(c) Their relative cheapness._ _(d) The daily Calorie requirement._ _(e) Food adulteration._ _(f) The relation of alcohol to the human system._

LABORATORY SUGGESTIONS

_Laboratory exercise._--Composition of common foods. The series of food charts supplied by the United States Department of Agriculture makes an excellent basis for a laboratory exercise to determine common foods rich in (_a_) water, (_b_) starch, (_c_) sugar, (_d_) fats or oils, (_e_) protein, (_f_) salts, (_g_) refuse. _Demonstration._--Method of using bomb calorimeter. _Laboratory and home exercise._--To determine the best individual balanced dietary (using standard of Atwater, Chittenden, or Voit) as determined by the use of the 100-Calorie portion. _Demonstration._--Tests for some common adulterants. _Demonstration._--Effect of alcohol on protein, _e.g._ white of egg. _Demonstration._--Alcohol in some patent medicines. _Demonstration._--Patent medicines containing acetanilid. Determination of acetanilid.

Why we Need Food.--A locomotive engine takes coal, water, oxygen, from its environment. A living plant or animal takes organic food, water, and oxygen from its environment. Both the living and nonliving machine do the same thing with this fuel or food. They oxidize it and release the energy in it. But the living organism in addition may use the food to repair parts that have broken down or even build new parts. _Thus food may be defined as something that releases energy or that forms material for the growth or repair of the body of a plant or animal._ The millions of cells of which the body is composed must be given material which will form more living matter or material which can be oxidized to release energy when muscle cells move, or gland cells secrete, or brain cells think.

Nutrients.--Certain nutrient materials form the basis of food of both plants and animals. These have been stated to be _proteins_ (such as lean meat, eggs, the gluten of bread), _carbohydrates_ (starches, sugars, gums, etc.), _fats_ and _oils_ (both animal and vegetable), _mineral matter_ and _water_.

Proteins.--Protein substances contain the element nitrogen. Hence such foods are called nitrogenous foods. Man must form the protoplasm of his body (that is, the muscles, tendons, nervous system, blood corpuscles, the living parts of the bone and the skin, etc.) in part at least from nitrogenous food. Some of this he obtains by eating the flesh of animals, and some he obtains directly from plants (for example, peas and beans). Proteins are the only foods available for tissue building. They may be oxidized to release energy if occasion requires it.

Fats and Oils.--Fats and oils, both animal and vegetable, are the materials from which the body derives part of its energy. The chemical formula of a fat shows that, compared with other food substances, there is very little oxygen present; hence the greater capacity of this substance for uniting with oxygen. The rapid burning of fat compared with the slower combustion of a piece of meat or a piece of bread illustrates this. A pound of butter releases over twice as much energy to the body as does a pound of sugar or a pound of steak. Human fatty tissue is formed in part from fat eaten, but carbohydrate or even protein food may be changed and stored in the body as fat.

Carbohydrates.--We see that the carbohydrates, like the fats, contain carbon, hydrogen, and oxygen. _Carbohydrates are essentially energy-producing foods._ They are, however, of use in building up or repairing tissue. It is certainly true that in both plants and animals such foods pass directly, together with foods containing nitrogen, to repair waste in tissues, thus giving the needed proportion of carbon, oxygen, and hydrogen to unite with the nitrogen in forming the protoplasm of the body.

Inorganic Foods.--Water forms a large part of almost every food substance. It forms about five sixths of a normal daily diet. The human body, by weight, is about two thirds water. About 90 per cent of the blood is water. Water is absolutely essential in passing off waste of the body. When we drink water, we take with it some of the inorganic salts used by the body in the making of bone and in the formation of protoplasm. Sodium chloride (table salt), an important part of the blood, is taken in as a flavoring upon our meats and vegetables. Phosphate of lime and potash are important factors in the formation of bone.

Phosphorus is a necessary substance for the making of living matter, milk, eggs, meat, whole wheat, and dried peas and beans containing small amounts of it. Iron also is an extremely important mineral, for it is used in the building of red blood cells. Meats, eggs, peas and beans, spinach, and prunes, are foods containing some iron.

Some other salts, compounds of calcium, magnesium, potassium, and phosphorus, have been recently found to aid the body in many of its most important functions. The beating of the heart, the contraction of muscles, and the ability of the nerves to do their work appear to be due to the presence of minute quantities of these salts in the body.

Uses of Nutrients.--The following table sums up the uses of nutrients to man:[36]--

Protein Forms tissue \ White of eggs (albumen), (muscles, tendon, } curd of milk (casein), lean and probably } All serve as meat, gluten of wheat, etc. fat) } _fuel_ and yield } _energy_ in form Fats Form fatty tissue. } of heat and muscular Fat of meat, butter, olive oil, } strength. oils of corn and wheat, etc. } } Carbohydrates Transformed into } Sugar, starch, etc. fat. /

Mineral matters (ash) Aid in forming bone, Phosphates of lime, potash, assist in digestion, soda, etc. aid in absorption and in other ways help the body parts do their work. Water used as a vehicle to carry nutrients, and enters into the composition of living matter.

Footnote 36: Adapted from Atwater, _Principles of Nutrition and Nutritive Value of Food_, U. S. Department of Agriculture, 1902.

Common Foods contain the Nutrients.--We have already found in our plant study that various plant foods are rich in different nutrients, carbohydrates forming the chief nutrient in the foods we call cereals, breads, cake, fleshy fruits, sugars, jellies, and the like. Fats and oils are most largely found in nuts and some grains. Animal foods are our chief supply of protein. White of egg and lean meat are almost pure protein and water. Proteins are most abundant, as we should expect, in those plants which are richly supplied with nitrogen; peas and beans, and in grains and nuts. Fats, which are melted into oils at the temperature of the body, are represented by the fat in meats, bacon, pork, lard, butter, and vegetable oils.

Water.--Water is, as we have seen, a valuable part of food. It makes up a very high percentage of fresh fruits and vegetables; it is also present in milk and eggs, less abundant in meats and fish, and is lowest in dried foods and nuts. The amount of water in a given food is often a decided factor in the cost of the given food, as can easily be seen by reference to the chart on page 283.

Refuse.--Some foods bought in the market may contain a certain unusable portion. This we call refuse. Examples of refuse are bones in meat, shells of eggs or of shellfish, the covering of plant cells which form the skins of potatoes or other vegetables. The amount of refuse present also plays an important part in the values of foods for the table. The table[37] on page 276 gives the percentages of organic nutrients, water, and refuse present in some common foods.