Applied Eugenics Part 41

Albinism. This appears to be a recessive, but probably involves multiple allelomorphs in man, as in other animals.

Brachydactyly, apparently a dominant. This is so much cited in text-books on Mendelism that the student might think it is a common character. As a fact, it is extremely rare, being found in only a few families. The similar trait of orthodactyly or symphalangism, which likewise appears to be a good Mendelian dominant, seems to exist in only one family. Traits like these, which are easily defined and occur very rarely, make up a large part of the cases of probably Mendelian heredity. They are little more than curiosities, their rarity and abnormal nature depriving them of evolutionary significance other than to demonstrate that Mendelian heredity does operate in man.

White blaze in the hair or, as it might better be called to show its resemblance to the trait found in other mammals, piebaldism. A rather rare dominant.[204]

Huntington's Ch.o.r.ea, which usually appears to be a good dominant, although the last investigators (Muncey and Davenport) found some unconformable cases.

A few abnormalities, such as a premature graying of the hair (one family cited by K. Pearson) are well enough attested to be admitted. Many others, such as baldness, are probably Mendelian but not yet sufficiently supported by evidence.

None of these characters, it will be observed, is of much significance eugenically. If the exact manner of inheritance of some of the more important mental and physical traits were known, it would be of value.

But it is not a prerequisite for eugenic action. Enough is known for a working program.

To sum up: the features in the modern view of heredity, which the reader must keep in mind, are the following:

1. That the various characters which make up the physical const.i.tution of any individual plant or animal are due to the action (concurrently with the environment, of course) of what are called, for convenience, factors, separable hypothetical units in the germ-plasm, capable of independent transmission.

2. That each visible character is due to the cooperative action of an indefinitely large number of factors; conversely, that each of these factors affects an indefinitely large number of characters.

APPENDIX E

USEFUL WORKS OF REFERENCE

The most complete bibliography is that published by the State Board of Charities of the State of New York (_Eugenics and Social Welfare Bulletin_ No. III, pp. 130, Albany, 1913).

An interesting historical review of eugenics, with critical comments on the literature and a bibliography of 100 t.i.tles, was published by A. E.

Hamilton in the _Pedagogical Seminary_, Vol. XXI, pp. 28-61, March, 1914.

Much of the important literature of eugenics has been mentioned in footnotes. For convenience, a few of the books which are likely to be most useful to the student are here listed:

GENETICS AND EUGENICS, by W. E. Castle. Harvard University Press, Cambridge, 1916.

HEREDITY AND ENVIRONMENT IN THE DEVELOPMENT OF MEN, by Edwin G.

Conklin. Princeton University Press, 1915.

HEREDITY IN RELATION TO EUGENICS, by C. B. Davenport, Henry Holt and Co., New York, 1911.

ESSAYS IN EUGENICS, by Francis Galton. Eugenics Education Society, London, 1909.

BEING WELL-BORN, by Michael F. Guyer. Indianapolis, Bobbs-Merrill Co., 1916.

THE SOCIAL DIRECTION OF HUMAN EVOLUTION, by W. E. Kellicott.

New York, 1911.

THE PHYSICAL BASIS OF SOCIETY, by Carl Kelsey. New York, D.

Appleton & Co., 1916.

EUGENICS, by Edward Schuster. Collins' Clear Type Press, London and Glasgow, 1913.

HEREDITY, by J. Arthur Thompson. Edinburgh, 1908.

GENETICS, by Herbert E. Walter. The Macmillan Co., New York, 1913.

AN INTRODUCTION TO EUGENICS, by W. C. D. Whetham and C. D.

Whetham. Macmillan and Co., London, 1912.

HEREDITY AND SOCIETY, by W. C. D. Whetham and C. D. Whetham.

Longmans, Green & Co., London, 1912.

THE FAMILY AND THE NATION, by W. C. D. Whetham and C. D.

Whetham. Longmans, Green & Co., London, 1909.

The publications of the Galton Laboratory of National Eugenics, University of London, directed by Karl Pearson, and of the Eugenics Record Office, Cold Spring Harbor, Long Island, N. Y., directed by C. B.

Davenport, furnish a constantly increasing amount of original material on heredity.

The princ.i.p.al periodicals are the _Journal of Heredity_ (organ of the American Genetic a.s.sociation), 511 Eleventh St., N. W., Was.h.i.+ngton, D.

C. (monthly); and the _Eugenics Review_ (organ of the Eugenics Education Society), Kingsway House, Kingsway, W. C., London (quarterly). These periodicals are sent free to members of the respective societies.

Members.h.i.+p in the American organization is $2 a year, in the English 1 guinea a year, a.s.sociate members.h.i.+p 5 s.h.i.+llings a year.

APPENDIX F

GLOSSARY

ACQUIRED CHARACTER, a modification of a germinal trait after cell fusion. It is difficult to draw a line between characters that are acquired and those that are inborn. The idea involved is as follows: in a standard environment, a given factor in the germ-plasm will develop into a trait which varies not very widely about a certain mean. The mean of this trait is taken as representing the germinal trait in its typical condition. But if the environment be not standard, if it be considerably changed, the trait will develop a variation far from the mean of that trait in the species. Thus an American, whose skin in the standard environment of the United States would be blonde, may under the environment of Cuba develop into a brunette. Such a wide variation from the mean thus caused is called an acquired character; it is usually impressed on the organism after the germinal trait has reached a full, typical development.

ALLELOMORPH (one another form), one of a pair of factors which are alternative to each other in Mendelian inheritance. Instead of a single pair, there may be a group of "multiple allelomorphs," each member being alternative to every other member of the group.

ALLELOMORPHISM, a relation between two or more factors, such that two which are present in one zygote do not both enter into the same gamete, but are separated into sister gametes.

BIOMETRY (life measure), the study of biology by statistical methods.

BRACHYDACTYLY (short-finger), a condition in which the bones, particularly of the fingers and toes, fail to grow to their normal length. In well-marked cases one of these is a reduction from three phalanges or joints to two.

CHARACTER (a contraction of "characteristic"), a term which is used, often rather vaguely, to designate any function, feature, or organ of the body or mind.

CHROMOSOME (color body, so called from its affinity for certain stains), a body of peculiar protoplasm, in the nucleus of the cell. Each species has its own characteristic number; the cells of the human body contain 24 chromosomes each.

CONGENITAL (with birth), present at birth. The term fails to distinguish between traits which are actually inherited, and modifications acquired during prenatal life. In the interest of clear thinking its use should be avoided so far as possible.

CORRELATION (together relation), a relation between two variables in a certain population, such that for every variation of one, there is a corresponding variation of the other. Mathematically, two correlated variables are thus mutually dependent. But a correlation is merely a statistical description of a particular case, and in some other population the same two variables might be correlated in a different way, other influences being at work on them.