A Civic Biology Part 28

[Ill.u.s.tration: Steps in budding. _a_, twig having suitable buds to use; _b_, method of cutting out bud; _c_, how the bark is cut; _d_, how the bark is opened; _e_, inserting the bud; _f_, the bud in place; _g_, the bud properly bound in place.]

_Budding._--If a given tree, for example, produces a kind of fruit which is of excellent quality, it is possible sometimes to attach parts of the tree to another strong tree of the same species that may not bear good fruit.

This is done by _budding_. A T-shaped incision is cut in the bark; a bud from the tree bearing the desired fruit is placed in the cut and bound in place. When a shoot from the embedded bud grows out the following spring, it is found to have all the characters of the tree from which it was taken.

[Ill.u.s.tration: Steps in tongue grafting. _a_, the two branches to be formed; _b_, a tongue cut in each; _c_, fitted together; _d_, method of wrapping.]

Grafting.--Of much the same nature is grafting. Here, however, a small portion of the stem of the closely allied tree is fastened into the trunk of the growing tree in such a manner that the two cut layers just under the bark will coincide. This will allow of the pa.s.sage of food into the grafted part and insure the ultimate growth of the twig. Grafting and budding are of considerable economic value to the fruit grower, as it enables him to produce at will, trees bearing choice varieties of fruit.[34]

Footnote 34: For full directions for budding and grafting, see Goff and Mayne, _First Principles of Agriculture_, Chap.

XIX, Mayne and Hatch, _High School Agriculture_, pp.

159-165, or Hodge, _Nature Study and Life_, pages 169-179.

Other Methods.--Other methods of plant propagation are by means of runners, as when strawberry plants strike root from long stems that run along the ground; layering, where roots may develop on covered up branches of blackberry or raspberry plants; slips, roots developing from stems which are cut off and placed in moist sand; from tubers, as in planting potatoes; and by means of bulbs, as the tulip or hyacinth. All of the above means of propagation are as.e.xual and are of importance in our problem of plant breeding.

[Ill.u.s.tration: Plant breeding plots. (Minnesota Experiment Station.)]

The Work of Gregor Mendel.--Fifty years ago, an Austrian monk, Gregor Mendel, found in breeding garden peas that these plants pa.s.sed on certain _fixed characters_, as the shape of the seed, the color of the pod when ripe, and others, and that when two pea plants of different characters were crossed, one of these characters would be likely to appear in the offspring of the second generation in the ratio of three to one. Such characters as would appear to the exclusion of others in the first crossing of the plants were called _dominant_, the ones not appearing, _recessive_ characteristics. When these seeds were again sown the ones bearing a recessive characteristic would produce only peas with this recessive characteristic, but the ones with a dominant characteristic might give rise to a pure dominant or to offspring having partly a dominant and partly a recessive character; pure dominants being to the mixed offspring in the ratio of 1 to 2. The pure dominants if bred with others like themselves would produce only pure dominants, but the cross breeds would again produce mixed offspring of three kinds in the ratio of one dominant to two cross breeds and one recessive. The feature of this work that interests us is that _unit_ characters are pa.s.sed along by heredity in the germ cells _pure_, that is, unchanged, from one generation to another, and independently of each other.

[Ill.u.s.tration: Ill.u.s.tration of Mendel's Law.]

Determiners of Character.--A child then resembles his parents in some definite particulars because certain _determiners_ of characters have been present in the germ cells of one of the parents. If the determiner of a certain character is _absent_ from the germ cells of both parents, it will be _absent_ in _all_ of their offspring.

These discoveries of Mendel are of the greatest importance in plant and animal breeding because they enable the breeder to isolate certain characters and by proper selection to breed varieties which have these desired characters, instead of waiting for a _chance_ union of the desired characters by nature.

Animal Breeding.--It has been pointed out that the domestication of wild animals, the horse, cattle, sheep, goats, and the dog, marked a great advance in civilization in the history of the earth's peoples. As the young of these animals came to be bred in captivity the peoples owning them would undoubtedly pick out the strongest and best of the offspring, killing off the others for food. Thus they came unconsciously to select and aid nature in producing a stronger and better stock. Later man began to recognize certain characters that he wished to have in horses, dogs, or cattle, and so by slow processes of breeding and "crossing" or hybridizing one nearly allied form with another the numerous groups of domesticated animals began to appear.

[Ill.u.s.tration: What has resulted from artificial selection among dogs.

(After Romanes.)]

In Darwin's time animal breeding was so far advanced that he got his ideas of selection by nature in evolution from the artificial selection practiced by animal breeders. A glance at the pictures will give some idea of the changes that have taken place in the form of some animals since man began to breed them a few thousand years ago.

[Ill.u.s.tration: The four-toed ancestor of the present horse, restored from a study of its fossil skeleton. (After Knight in American Museum of Natural History.)]

Some Domesticated Animals.--Our domesticated dogs are descended from a number of wolflike forms in various parts of the world. All the present races of cats, on the other hand, seem to be traced back to Egypt. Modern horses are first noted in Europe and Asia, but far older forms flourished on the earth in former geologic periods. It is interesting to note that America was the original home of the horse, although at the time of the earliest explorers the horse was unknown here, the wild horse of the Western plains having arisen from horses introduced by the Spaniards. Long ages ago, the first ancestors of the horse were probably little animals about the size of a fox. The earliest horse we have knowledge of had four toes on the fore and three toes on the hind foot. Thousands of years later we find a larger horse, the size of a sheep, with a three-toed foot. By gradual changes, caused by the tendency of the animals to vary and by the action of the surroundings upon the animal in preserving these variations, there was eventually produced our present horse, an animal with legs adapted for rapid locomotion, with feet particularly fitted for the life in open fields, and with teeth which serve well to seize and grind herbage.

Knowledge of this sort was also used by Darwin to show that constant changes in the form of animals have been taking place since life began on the earth.

The horse, which for some reason disappeared in this country, continued to exist in Europe, and man, emerging from his early savage condition, began to make use of the animal. We know the horse was domesticated in early Biblical times, and that he soon became one of man's most valued servants.

In more recent times, man has begun to change the horse by breeding for certain desired characteristics. In this manner have been established and improved the various types of horses familiar to us as draft horses, coach horses, hackneys, and the trotters.

It is needless to say that all the various domesticated animals have been tremendously changed in a similar manner since civilized man has come to live on the earth. When we realize the very great amount of money invested in domesticated animals; that there are over 60,000,000 each of sheep, cattle, and swine and over 20,000,000 horses owned in this country, then we may see how very important a part the domestic animals play in our lives.

Improvement of Man.--If the stock of domesticated animals can be improved, it is not unfair to ask if the health and vigor of the future generations of men and women on the earth might not be improved by applying to them the laws of selection. This improvement of the future race has a number of factors in which we as individuals may play a part. These are personal hygiene, selection of healthy mates, and the betterment of the environment.

Personal Hygiene.--In the first place, good health is the one greatest a.s.set in life. We may be born with a poor bodily machine, but if we learn to recognize its defects and care for it properly, we may make it do its required work effectively. If certain muscles are poorly developed, then by proper exercise we may make them stronger. If our eyes have some defect, we can have it remedied by wearing gla.s.ses. If certain drugs or alcohol lower the efficiency of the machine, we can avoid their use. With proper _care_ a poorly developed body may be improved and do effective work.

Eugenics.--When people marry there are certain things that the individual as well as the race should demand. The most important of these is freedom from germ diseases which might be handed down to the offspring.

Tuberculosis, syphilis, that dread disease which cripples and kills hundreds of thousands of innocent children, epilepsy, and feeble-mindedness are handicaps which it is not only unfair but criminal to hand down to posterity. The science of being well born is called _eugenics_.

[Ill.u.s.tration: In this and the following diagrams the circle represents a female, the square a male. N means normal; F means feeble-minded; A, alcoholic; T, tubercular; _Sx_, s.e.xually immoral; _Sy_, having syphilis.

This chart shows the record of a certain family for three generations. A normal woman married an alcoholic and tubercular man. He must have been feeble-minded also as two of his children were born feeble-minded. One of these children married another feeble-minded woman, and of their five children two died in infancy and three were feeble-minded. (After Davenport.)]

[Ill.u.s.tration: This chart shows that feeble-mindedness is a characteristic sure to be handed down in a family where it exists. The feeble-minded woman at the top left of the chart married twice. The first children from a normal father are all normal, but the other children from an alcoholic father are all feeble-minded. The right-hand side of the chart shows a terrible record of feeble-mindedness. Should feeble-minded people be allowed to marry? (After Davenport.)]

The Jukes.--Studies have been made on a number of different families in this country, in which mental and moral defects were present in one or both of the original parents. The "Jukes" family is a notorious example. The first mother is known as "Margaret, the mother of criminals." In seventy-five years the progeny of the original generation has cost the state of New York over a million and a quarter of dollars, besides giving over to the care of prisons and asylums considerably over a hundred feeble-minded, alcoholic, immoral, or criminal persons. Another case recently studied is the "Kallikak" family.[35] This family has been traced back to the War of the Revolution, when a young soldier named Martin Kallikak seduced a feeble-minded girl. She had a feeble-minded son from whom there have been to the present time 480 descendants. Of these 33 were s.e.xually immoral, 24 confirmed drunkards, 3 epileptics, and 143 _feeble-minded_. The man who started this terrible line of immorality and feeble-mindedness later married a normal Quaker girl. From this couple a line of 496 descendants have come, with _no_ cases of feeble-mindedness.

The evidence and the moral speak for themselves!

Footnote 35: The name Kallikak is fict.i.tious.

Parasitism and its Cost to Society.--Hundreds of families such as those described above exist to-day, spreading disease, immorality, and crime to all parts of this country. The cost to society of such families is very severe. Just as certain animals or plants become parasitic on other plants or animals, these families have become parasitic on society. They not only do harm to others by corrupting, stealing, or spreading disease, but they are actually protected and cared for by the state out of public money. Largely for them the poorhouse and the asylum exist. They take from society, but they give nothing in return. They are true parasites.

The Remedy.--If such people were lower animals, we would probably kill them off to prevent them from spreading. Humanity will not allow this, but we do have the remedy of separating the s.e.xes in asylums or other places and in various ways preventing intermarriage and the possibilities of perpetuating such a low and degenerate race. Remedies of this sort have been tried successfully in Europe and are now meeting with success in this country.

Blood Tells.--Eugenics show us, on the other hand, in a study of the families in which are brilliant men and women, the fact that the descendants have received the _good_ inheritance from their ancestors. The following, taken from Davenport's _Heredity in Relation to Eugenics_, ill.u.s.trates how one family has been famous in American History.

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."

[Ill.u.s.tration: This record shows the inheritance of artistic ability (black circles and squares). (After Davenport.)]

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 a.s.sociation.

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 Publis.h.i.+ng Company.

G.o.ddard, _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.