Sok ae Eee ee LEE ae, CORNER UNIVERSITY LIBRARY BOUGHT WITH THE INCOME OF THE SAGE ENDOWMENT FUND GIVEN IN 1891 BY HENRY WILLIAMS SAGE Cornell University Library QH 431.D24 = ~ Mii 3 1924 024 562 401 OLIN LIBRARY — C DATE DUE GAYLORD PRINTEDINU.S.A Cornell University Library The original of this book is in the Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924024562401 PLATE I EYE COLORS IN MAN A. Pramenr or CHO- roip Coat AND PIGMENT or Inis Apsent. 1. The ALBINO eye. Red from unobscured blood vessels. BL. Pigment or Cuyo- ROID PRESENT. a. Ints wirHocr TRUE Pigment. 2. Buur. Due to a purple layer on back of eye. Bb. Iris with TRE PIGMENTS. a. Lipochrome or yellow pigment. 3. GREEN or cat. eye. Yellow pigment on blue background, b. Melanie or black pig- ment. 4. Hazen or gray eye. Dilute brown pig- ment around pupil only. 5. Brown eye. Melanic pigment; various shades from various dilutions. 6. Buack — eve. An abundance of melanic pig- ment. HEREDITY IN RELATION TO EUGENICS BY CHARLES BENEDICT DAVENPORT CARNEGIE INSTITUTION OF WASHINGTON DIRECTOR, DEPARTMENT OF EXPERIMENTAL EVOLUTION COLD SPRING HARBOR, LONG ISLAND, N. Y. SECRETARY OF THE EUGENICS SECTION AMERICAN BREEDERS’ ASSOCIATION NEW YORK HENRY HOLT AND COMPANY 1911 — ' A.26\243 Coprrieut, 1911 BY HENRY HOLT AND COMPANY PRESS OF T. MOREY & SON GREENFIELD, MASS., U. 8. A, 2rd TO MRS. E. H. HARRIMAN IN RECOGNITION OF THE GENEROUS ASSISTANCE SHE HAS GIVEN TO RESEARCH IN EUGENICS THIS BOOK IS GRATEFULLY DEDICATED PREFACE REcENT great advances in our knowledge of heredity have revolutionized the methods of agriculturalists in im- proving domesticated plants and animals. It was early recognized that this new knowledge would have a far- reaching influence upon certain problems of human society —the problems of the unsocial classes, of immigration, of population, of effectiveness, of health and vigor. Now, great as are the potentialities of the new science of heredity in its application to man it must be confessed that they are not yet realized. A vast amount of investigation into the laws of the inheritance of human traits will be required before it will be possible to give definite instruction as to fit marriage matings. Our social problems still remain prob- lems. For a long time yet our watchword must be investi- gation. The advance that has been made so far is chiefly in getting a better method of study. In this book I have sought to explain this new method. An application of this method to some specific problems, especially to the transmission of various human traits and susceptibilities to disease, has been attempted. The sug- gestions made are by no means final but are made to illus- trate the general method and give the most probable con- clusions. Only with much more accurate data can the laws of inheritance of family peculiarities be definitely de- termined. Some general consequences of the new point of view for the American population have been set forth in Chap- ters IV to VI. Their essential truth will, I trust, be generally ill iv PREFACE recognized. In any case it will not be amiss to point out the fundamental difference between the modern eugenical and the contrasted or ‘‘euthenical’”’ standpoints. As a matter of fact the eugenic teachings that we think of as new are very old. Modern medicine is responsible for the loss of appreciation of the power of heredity. It has had its atten- tion too exclusively focussed on germs and conditions of life. It has neglected the personal element that helps determine the course of every disease. It has begotten a wholly impersonal hygiene whose teachings are false in so far as they are laid down as universally applicable. It has forgotten the fundamental fact that all men are created bound by their protoplasmic makeup and unequal in their powers and responsibilities. As indicated, it is the aim of this book to incite to further investigation. Some space is devoted to the eugenics move- ment—a movement which it is hoped will, in this country, for the present, take mainly the form of investigation. To this movement the Eugenics Record Office (a branch of the work of the American Breeders’ Association) is dedicated. The Eugenics Record Office wishes to get in touch with all persons interested in the eugenics movement. It invites every person who is willing to do so to record his heritage and place the record on file at the Record Office. “Drop a postal card” at once to the Eugenics Record Office, Cold Spring Harbor, New York, and ask for the blank schedule they furnish. It is understood that all data deposited in this way will be held as confidential and be used only for scientific purposes. The data received are carefully pre- served in a fireproof vault and indexed so as to be avail- able to the student. Specifically, the Record Office seeks pedigrees of families in which one or more of the following traits appear:—short stature, tallness, corpulency, special talents in music, art, literature, mechanics, invention and PREFACE Vv mathematics, rheumatism, multiple sclerosis, hereditary ataxy, Méniére’s disease, chorea of all forms, eye defects of all forms, otosclerosis, peculiarities of hair, skin and nails (especially red hair), albinism, harelip and cleft palate, peculiarities of the teeth, cancer, Thomsen’s disease, hemo- philia, exophthalmic goiter, diabetes, alkaptonuria, gout, peculiarities of the hands and feet and of other parts of the skeleton. We do not appeal primarily to physicians for this information but to the thousands of intelligent Americans who love the truth and want to see its interests advanced. At the same time, physicians can aid in the work by in- ducing persons with bodily or mental peculiarities that run through their families to send to the Record Office for blank schedules on which to record the method of inherit- ance of the trait in question. Thus every one can share in the eugenics movement. The Eugenics Record Office will be glad to assist in the establishment of local eugenics societies which shall become centers for the study of local blood-lines and for local in- struction. The Office seeks to assist state officials in the study of the classes which are supported and protected by the State, and to assist the States to locate the centers in which their defectives and delinquents are being bred. It is believed that a little money spent in studying the sources of reproduction of persons who are destined to become state wards will prove a highly profitable investment, since it may lead to steps that will diminish such reproduction. In the preparation of the present volume the author has been aided by many hands. Professor James A. Field, of the University of Chicago, has kindly read the proof and made valuable suggestions. The bibliography and the pedi- gree charts were largely prepared by Miss Amey B. Eaton, of the Eugenies Record Office. Professor E. B. Wilson has generously granted me the use of Figures 1 to 6 from his vi PREFACE invaluable book, ‘‘The Cell in Development and Inherit- ance.” Hundreds of persons have voluntarily contributed the data upon which the conclusions that have been drawn are based. My friend and colleague, Mr. H. H. Laughlin, Superintendent of the Eugenics Record Office, has assisted in many points and has contributed the frontispiece. My wife has, as usual, revised the manuscript and prepared it for the printer. The Trustees of the Carnegie Institution have granted me exceptional opportunities for the prosecu- tion of the work. Last, but by no means least, this work and the collection of data out of which it has grown have been made possible by the financial assistance and by the personal stimulus and advice given by the lady to whom, in insufficient recognition, this book is, with her permis- sion, dedicated. To all those who have so kindly assisted me I return thanks. I trust the book will be useful to hu- manity, so as to justify them for the pains they have taken to bring it to pass. Be D, Carnegie Institution of Washington Station for Experimental Evolution Cold Spring Harbor, N. Y. # @ 44 who et OaRwNe ili ao CONTENTS CHAPTER I EUGENICS: ITS NATURE, IMPORTANCE AND AIMS . Waat EUGENICS 18 . Tot Neep or EvcEnics ‘ . Tot GENERAL PROCEDURE IN Mente! ‘Eugenes ‘ CHAPTER II THE METHOD OF EUGENICS . Unit CaaractTers AND THEIR COMBINATIONS Tue MECHANISM OF THE INHERITANCE OF Caanscrennarts Tue Laws or HEREDITY . INHERITANCE OF MULTIPLE Guanenins ‘i , . Herepity or Sex anpD oF “SEX-LIMITED’’ CHARACTERS . Tae APPLICATION OF THE Laws or HEREDITY To EUGENICS CHAPTER III THE INHERITANCE OF FAMILY TRAITS . Eye Coior . Harr Conor . Harr Form Sxin Cotor STATURE . Tora Bopy Wercut . Musicat ABILITY . ABILITY IN ARTISTIC Conposmron . ABILITY IN LITERARY COMPOSITION . . MEcHANICAL SKILL . CALCULATING ABILITY . MEmMory . CoMBINED "Sion. AND Sunciany OF 7 ences Auipenies . TEMPERAMENT . HANDWRITING PAGE Vill CONTENTS 16. GeneraL Bopiny ENERGY . . 1. ee ee ew ee we ee «6B 17. Genrrat Bopity SrReENGTH . . we wee ee ee ee) «CS 18. Genera, Menran ABILITY. . 2 1 ee ee ee ee ee (68 19. PBIGEESY 2s. “yo. och) Ge, Ge Gus At, GB ee a ea, 720, INSANTEY 6 kk ew 77 91 PAUPBRISM. 22 Gdbva. Wy). acest GA era Rs ee ate ah “BO 22, NaRCOTISM . . a cee gae cd van, tae) wg Niet RD Se Ae Ee ee SB 23. CRIMINALITY . . . aes Reva nie eh ty eae alas! teas, Mts 38S 24. OrguR NERVouS Themgia Or etcde te C&, Boke Mente Ep ek tal, a. The General Problem . . . . we ee ee ee ee 92 b. The Neuropathic Makeup . . ....... +. + 98 c. Cerebral Hemorrhage . . . . . . ee eee ee OO d. Cerebral Palsy of Infancy .. b) "ig sas tel ae 1H ao Mats WOE e. Multiple or Disseminated Sclerosis gos eihe er oe ney Gates tt, BOD. f. Hereditary Ataxy dy ob. Boe Ka RR ae te wy BD g. Méniére’s Disease . . . . . ee we ee «dO h. Chorea . . . Be bots, GD shee Gee cB: aes Ge Cie 101 4. Huntington’s Chore GE a eda ee ho OP Bo we ee Oe Ge G02: gu Hysteria: ge ee es ee ae ee G08 25. RHEUMATISM << 4 = 4 2 es & ¥ @ # woe we s « 104 26. Speecu-DeFmcTs ........ . 4... 4 - .- + + 105 27. Derects or THE Eve .......... =.=... . 107 u. Anomalies of Iris . . iy Be BW Gs kt Catecke, ie, 0S b. Reduction in Size of the Eyeball fonse Bose, esos. cain 109 c. Atrophy of the ean INGtVé6 Me a) ae ale Se es a ce eg ALO d. Cataract . . . be ee Se eee ae te ee ee e. Displaced Lens . . . fe OR Ra ee ge f. Degeneracy of the Comea Dy Re a ke ae Go g. Glaucoma . . ar ues eaves Gide VGN. wee Gee Se Gor a uth Hy 4 CSENS h. Moxalophtlialnas ot cio ee Sor he ti apts Be Sade ser Os Ge ELS 1. Nystagmus . . 115 k. Paralysis or Timperfect ‘Development of ‘the Muscles a Eye andLids ... Yo ew ow wo ek ae l. Pigmentary ‘DexendreGion of they Refitia Qo ee ae aes ae EEG: m. Night blindness . . 2. 2. 1 1 1 we ee ee eee 8 n. Color blindness . . . . . . . 1 ee eee eee 120 OO. MYOple. ee Bok we ewe ee 6 ae Ss @ TBI p. Astigmatism ©. 2... we ee ee ee we ee 128 28, HAR, DEFECTS: 5. ea & & wow Bk we ew we we ew a 128 a. Deaf Mutism. . . 2... 1. ee ee ee eee 124 b. Otosclerosis . . Be Re Rote eve Bis eocate Gan a a 4.1 OO c. Catarrhal Affections: BS Siete ds May att Yer Bs eed: LES, oa S180 29. Skin Diseases . . . ys ay eh Ge GaAs, “te a oe PBT a. Congenital TeaniaatiC Petanitvas ie) Oe Be ee a, 1182 jb; Psoriasis’ 403 a eo we we a Re we BD c Ichthyosig » 6 6 6 ee ee ee ww ee ee ew 184 ny a Ie Oe ie Ee 30. 31. 32. 33. 34. 36. . DIsEAsES OF THE ALIMENTARY SYSTEM 38. 39. 40. CONTENTS d. Thickening of the Outer Layer of the Skin . EpmERMAL ORGANS sy itn bee Be ; a. The Skin Glands b. Hair . c. Nails d. Teeth ‘ 5 e. Harelip and Cleft Palate ‘ CANCER AND TUMORS . DisEasrs or THE Muscunar Sarai a. Thomsen’s Disease . x b. Certain Muscular ‘Atrophies ‘ c. Trembling . . d. Hernia é DISEASES OF THE Bios a. Chlorosis . 7 b. Progressive Perticious Kevsnite z c. Nosebleed . d. Telangiectasis . e. Hemophilia . f. Splenic Anemia with: nilarwamant of the Bolecn : Diseases oF THE THYROm GLAND a. Cretinism b. Goitre Z c. Exophthalmic Guitre . DISEASES OF THE VASCULAR Sea: a. Heart b. Arteriosclerosis ‘ DISEASES OF THE RESPIRATORY vaiise a. Diabetes Insipidis Diseases or EXcRETION a. Alkaptonuria . . b. Cystinuria and Cystin Tnflliration - e. Hematuria. . i ads Gk a d. Urinary Calculi e. Gout . j REPRODUCTIVE Onaas a. Cryptorchism . b. Hypospadias . . c. Prolapsus of the Deras aad Steiity SKELETON AND APPENDAGES a. Achondroplasy b. Scoliosis . . c. Exostoses ; d. Absence of clavicles . e. Congenital Dislocation of the Thigh Bone—Pelvis Joint x CONTENTS PAGE f. Polydactylism. . . 2. 2. 1. ee ee ee ee we 178 g. Syndactylism . . 2. 2. 2 1. ww ee eee ew ee 176 h. Brachydactylism . Boch ee ing oa Sle ee LE t. Other Deformities of he Hands, Gh cobs ee hin, oS CHoSas eects Ae Al WINS) &) Go. ew Re ES we)! ae lg ee pe ae ten 80) CHAPTER IV THE GEOGRAPHIC DISTRIBUTION OF INHERITABLE TRAITS 1. Tap Dispersion or TRAITS ......... =... ~. 181 2. CONSANGUINITY IN MARRIAGE. . ...... . . « « + 184 3. Barriers TO MarRRIAGE SELECTION. . . . . . .. . . « 189 A. PHYSIOGRAPHIC BARRIERS . . . . . . .. 2... . « 189 a. Barrier of Water Be Nee ae. Bee! pled GSM alg! men “age, atte oe 1190 b. Barrier of Topography , oe. wR ee ow = = « 196 B. SOCIAL BARRIERS . . < ea Se ew we e we we 198 c. The Barrier of the Social Stataa Be te tle Soe ae I, kee ae ate ot) AOS: d. The Barrier of Language . . . . .... =... +. . 200 e. The Barrier of Race. . t, Wd cxf ole ok eta en a Ry Gt, we 9202 f. The Barrier of Religious Sect Bs di SAGE Ta cee lade Ghee SS? Gee 202 CHAPTER V MIGRATIONS AND THEIR EUGENIC SIGNIFICANCE 1. Primitive MicRaTIons . : be de rege (p) aGicte ig) ek a Wg’ e204: 2. Harty ImmicraTIon To AMERICA oe we ee Boe we a ee BOS 3. Recent IMMIGRATION TO AMERICA . .... ..... . 212 a. Irish . Sag a eR RP oe ee ate a a te BIB b. Germans 3 Ain Be sah Side, ibe OS tet, ere . . 214 c. Scandinavians .......... . . . . . . 214 d. Austro-Hungarians . . . . . . . ee ee U5 €, THCDIEWS 3. los oe ti hook Jee we ae ayn ee ee BES Fs Wtalians® & 2. ge gp Se! on & alk oe a a a IE g- Poles. eh. RA SO eS Ode a ae a G DIB h. Portuguese. . BSG BS Te, hes Sone MMs ae ch ee DLS. 4, CONTROL oF Thnabenaiongs BS Hem ods, ees IRS: Wee. Bids weeks rte leg) coe DOS CHAPTER VI THE INFLUENCE OF THE INDIVIDUAL ON THE RACE 1. Exizaseta ToUTtue . : SD tort, Stee teh ae a ate BOR 2. Tae First Famities or Vmonws ee 4 ee a ce ow a 228 CONTENTS xi PAGE 3. Tee Kentucny Arisrooracy . . . . .. 2... ss ss 230 4 PHD JUKES. xox ak ko ke a a es a ae 28 5. Toe IsHMaELiTES . . 2... . 1. ww ee ee ewe 284 6. Tae Banger Famiry. . . . . 1... eee ee ee 287 CHAPTER VII THE STUDY OF AMERICAN FAMILIES 1. Taw Srupy or GENEALOGY ....... . . 4 «6 « « 239 2. Famity Traits . . . BT yp a. ae a te a ee wp AL 3. Tan Inrecrity oF Famiiy TRatra ewe eR Oe os we a 4D CHAPTER VIII EUGENICS AND EUTHENICS 1. Herepity AND ENVIRONMENT. . ..... . 2. se « « 252 2. EUGENICS AND UPLIFT .. . fo oR eo ow kw « Dod 3. Tae ELIMINATION OF Uapennxene Trarrs bop ewe we 4 wa BQb5 4. Tue SaLVATION OF THE Race THroucH Herepiry .... . 260 5. Tae SociotocicaL AspecT or EuGrenics . ....... . 261 6. FREEDOM OF THE WILL AND RESPONSIBILITY . .... . . 264 CHAPTER IX THE ORGANIZATION OF APPLIED EUGENICS 1. State Evcenic Surveys .. . Hes Seas ae Sen Sa ee BE 2. A CLEARING Housr For HEREDITY Dave oe oR Ware: Goo QOD BIBLIOGRAPHY . . . 273 APPENDIX: LisT OF Piaces ‘Ruyeennp 10, ‘Guosnapereaue Anpance 289 INDEX. 4.4 S % A Sow woe w wok & @ ap aw & 2 ye 2 OL PLATES e I. Eye Cotors1n Man .. . . . « . Frontispiece Il. Wave oF IMMIGRATION INTO THE Unrrep Srarns, FROM ALL Counrriss, 1820-1910 . . . 2... ee ee ee ee + 218 HEREDITY IN RELATION TO EUGENICS CHAPTER I EUGENICS: ITS NATURE, IMPORTANCE AND AIMS 1. Waar Eveenics Is Eugenics is the science of the improvement of the human race by better breeding or, as the late Sir Francis Galton expressed it:—‘‘The science which deals with all influences that improve the inborn qualities of a race.’”’ The eugenical standpoint is that of the agriculturalist who, while recog- nizing the value of culture, believes that permanent advance is to be made only by securing the best ‘‘blood.”’ Man is an organism—an animal; and the laws of improvement of corn and of race horses hold true for him also. Unless people accept this simple truth and let it influence marriage selection human progress will cease. . Eugenics has reference to offspring. The success of a marriage from the standpoint of eugenics is measured by the number of disease-resistant, cultivable offspring that come from it. Happiness or unhappiness of the parents, the principal theme of many novels and the proceedings of divorce courts, has little eugenic significance; for eugenics has to do with traits that are in the blood, the protoplasm. The superstition of prenatal influence and the real effects 1 2 HEREDITY IN RELATION TO EUGENICS of venereal disease, dire as they are, lie outside the pale of eugenics in its strictest sense. But no lover of his race can view with complaisance the ravages of these diseases nor fail to raise his voice in warning against them. The parasite that induces syphilis is not only hard to kill but it frequently works extensive damage to heart, arteries and brain, and may be conveyed from the infected parent to the unborn child. Gonorrhea, like syphilis, is a parasitic disease that is commonly contraeted during illicit sexual intercourse. Conveyed by an inftoted man to his wife it frequently causes her to become sterile. Venereal diseases are disgenic agents of the first magnitude and of growing importance. , The danger of acquiring them should be known to all young men. Society might well demand that before a marriage license is issued the man should present a certi- ficate, from a reputable physician, of freedom from them. Fortunately, nature protects most of her best blood from these diseases; for the acts that lead to them are repugnant to strictly normal persons; and the sober-minded young women who have had a fair opportunity to make a selec- tion of a consort are not attracted by the kind of men who are most prone to sex-immorality. 2. Tae NEED or EUGENICS The human babies born each year constitute the world’s most valuable crop. Taking the population of the globe to be one and one-half billion, probably about 50 million children are born each year. In the continental United States with over 90 million souls probably 24% million children are annually born. When we think of the influence of a single man in this country, of a Harriman, of an Edison, of a William James, the potentiality of these 214 million annually can be dimly conceived as beyond computation. But for better or worse this potentiality is far from being ITS NATURE, IMPORTANCE AND AIMS 3 realized. Nearly half a million of these infants die before they attain the age of one year, and half of all are dead be- fore they reach their 23rd year—before they have had much chance to affect the world one way or another. How- ever, were only one and a quarter million of the children born each year in the United States destined to play an important part for the nation and humanity we could look with equanimity on the result. But alas! only a small part of this army will be fully effective in rendering productive our three million square miles of territory, in otherwise utilizing the unparalleled natural resources of the country, and in forming a united, altruistic, God-serving, law-abiding, effective and productive nation, leading the remaining 93 per cent of the globe’s population to higher ideals. On the contrary, of the 1200 thousand who reach full maturity each year 40 thousand will be ineffective through temporary sickness, 4 to 5 thousand will be segregated in the care of institutions, unknown thousands will be kept in poverty through mental deficiency, other thousands will be the cause of social ‘disorder and still other thousands will be required to tend and control the weak and unruly. We may estimate at not far from 100 thousand, or 8 per cent, the number of the non-productive or only slightly produc- tive, and probably this proportion would hold for the 600 thousand males considered by themselves. The great mass of the yearly increment, say 550 thousand males, constitute a body of solid, intelligent workers of one sort and another, engaged in occupations that require, in the different cases, various degrees of intelligence but are none the less valuable in the progress of humanity, Of course, in these gainful occupations the men are assisted by a large number of their sisters, but four-fifths of the women are still engaged in the no less useful work of home-making. The ineffectiveness of 6 to 8 per cent of the males and the 4 HEREDITY IN RELATION TO EUGENICS probable slow tendency of this proportion to increase is deserving of serious attention. It is a reproach to our intelligence that we as a people, proud in other respects of our control of nature, should have to support about half a million insane, feeble-minded, epileptic, blind and deaf, 80,000 prisoners and 100,000 paupers at a cost of over 100 million dollars per year. A new plague that rendered four per cent of our population, chiefly at the most productive age, not merely incompetent but a burden costing 100 million dollars yearly to support, would instantly attract universal attention. But we have become so used to crime, disease and degeneracy that we take them as necessary evils. That they were so in the world’s ignorance is granted; that they must remain so is . denied. 38. Tot GENERAL PROCEDURE IN APPLIED EUGENICS The general program of the eugenist is clear—it is to improve the race by inducing young people to make a more reasonable selection of marriage mates; to fall in love in- telligently. It also includes the control by the state of the propagation of the mentally incompetent. It does not imply destruction of the unfit either before or after birth. It certainly has only disgust for the free love propaganda that some ill-balanced persons have sought to attach to the name. Rather it trusts to that good sense with which the majority of people are possessed and believes that in the life of such there comes a time when they realize that they are drifting toward marriage and stop to consider if the contemplated union will result in healthful, mentally well-endowed offspring. At present there are few facts so generally known that they will help such persons in their inquiry. It is the province of the new science of eugenics to study the laws of inheritance of human traits and, as ITS NATURE, IMPORTANCE AND AIMS 5 these laws are ascertained, to make them known. There is no doubt that when such laws are clearly formulated many certainly unfit matings will be avoided and other fit matings that have been shunned through false scruples will be happily contracted. CHAPTER II THE METHOD OF EUGENICS 1. Unir CHARACTERS AND THEIR COMBINATION When we look among our acquaintances we are struck by their diversity in physical, mental, and moral traits. Some of them have black hair, others brown, yellow, flaxen, or red. The eyes may be either blue, green, or brown; the hair straight or curly; noses long, short, narrow, broad, straight, aquiline, or pug. They may be liable to colds or resistant; with weak digestion or strong. The hearing may be quick or dull, sight keen or poor, mathematical ability great or small. The disposition may be cheerful or mel- ancholic; they may be selfish or altruistic, conscientious or liable to shirk. It is just the fact of diversity of character- istics of people that gives the basis for the belief in the practicability of improving the qualities of the ‘human harvest.” For these characteristics are inheritable, they are independent of each other, and they may be combined in any desirable mosaic. The method of inheritance of these characteristics is not always so simple as might be anticipated. Extensive studies of heredity have, of late years, led to a more precise knowledge of the facts. The element of inheritance is not the individual as a whole nor even, in many cases, the traits as they are commonly recognized but, on the con- trary, certain unit characters. What are, indeed, units in inheritance and what are complexes it is not always easy 6 THE METHOD OF EUGENICS 7 to determine and it can be determined only by the results of breeding. To get at the facts it is necessary to study the progeny of human marriages. Now marriage can be and is looked at from many points of view. In novels, as the climax of human courtship; in law, largely as a union of two lines of property-descent; in society, as fixing a certain status; but in eugenics, which considers its biological aspect, marriage is an experiment in breeding; and the children, in their varied combinations of characters, give the result of the experiment. That marriage should still be only an experiment in breeding, while the breeding of many animals and plants has been reduced to a science, is ground for reproach. Surely the human product is su- perior to that of poultry; and as we may now predict with precision the characters of the offspring of a particular pair of pedigreed poultry so may it sometime be with man. As we now know how to make almost any desired combina- tion of the characters of guinea-pigs, chickens, wheats, and cottons so may we hope to do with man. At present, matings, even among cultured people, seem to be made at haphazard. Nevertheless there is some evi- dence of a crude selection in peoples of all stations. Even savages have a strong sense of personal beauty and a selec- tion of marriage mates is influenced by this fact, as Darwin has shown. It is, indeed, for the purpose of adding to their personal attractiveness that savage women or men tattoo the skin, bind up various parts of the body including the feet, and insert ornaments into lips, nose and ears. Among civilized peoples personal beauty still plays a part in selec- tive mating. If, as is sometimes alleged, large hips in the female are an attraction, then such a preference has the eugenic result that it tends to make easy the birth of large, well-developed babies, since there is probably a correlation between the spread of the iliac bones of the pelvis and the 8 HEREDITY IN RELATION TO EUGENICS size of the space between the pelvic bones through which the child must pass. Even a selection on the ground of social position and wealth has a rough eugenic value since success means the presence of certain effective traits in the stock. The general idea of marrying health, wealth, and wisdom is a rough eugenic ideal. A curious antipathy is that of red haired persons of opposite sex for each other. Among thousands of matings that I have considered I have found only two cases where both husband and wife are red headed, and I am assured by red haired persons that the antipathy exists. If, as is sometimes alleged, red hair is frequently associated with a condition of nervous irri- tability this is an eugenic antipathy. In so far as young men and women are left free to select their own marriage mates the widest possible acquaintance with different sorts of people, to increase the amplitude of selection, is evidently desirable. This is the great argument for coeducation of the sexes both at school and college, that they may increase the range of their experience with people and gain more discrimination in selection. The custom that prevails in America and England of free selec- tion of mates makes the more necessary the proper in- struction of young people in the principles of eugenical matings. The theory of independent unit characters has an im- portant bearing upon our classifications of human beings and shows how essentially vague and even false in con- ception these classifications are. A large part of the time and expense of maintaining the courts is due to this anti- quated classification with its tacit assumption that each class stands as a type of men. Note the extended discus- sions in courts as to whether A belongs to the white race or to the black race, or whether B is feeble-minded or not. Usually they avoid, as if by intention, the fundamental THE METHOD OF EUGENICS 9 question of definition, and if experts be called in to give a definition the situation is rendered only worse. Thus one expert will define a feeble-minded person as one incapable of protecting his life against the ordinary hazards of civili- zation, but. this is very vague and the test is constantly changing. For a person may be quick-witted enough to avoid being run over by a horse and carriage but not quick enough to escape an automobile. .A second expert will define a feeble-minded person as one who cannot meet all (save two) of the(Binet test) for three years below his own; if he fail in one only he is no longer feeble-minded. But this definition seems to me socially insufficient just because there are moral imbeciles who can answer all but the moral question for their proper age. Every attempt to classify persons into a limited number of mental categories ends unsatisfactorily. The facts seem to be rather that no person possesses all of the thousands of unit traits that are possible and that are known in the species. Some of these traits we are better off without but the lack of others is a serious handicap. If we place in the feeble-minded class every person who lacks any known mental trait we extend it to include practically all persons. If we place there only those who lack some ‘trait desirable in social life, again our class is too inclusive. Perhaps the best definition would be: ‘‘deficient in some socially important trait’? and then the class would include (as perhaps it should) also the sexually immoral, the crim- inalistic, those who cannot control their use of narcotics, those who habitually tell lies by preference, and those who run away from school or home. If from the term “‘feeble- minded”? we exclude the sexually immoral, the criminal- istic, and the narcotics such a restriction carried out into practice would greatly reduce the population of institutions for that class. Thus one sees that a full and free recogni- 10 HEREDITY IN RELATION TO EUGENICS tion of the theory of unit characters in its application to man opens up large social, legal and administrative ques- tions and leads us in the interests of truth, to avoid classify- ing persons and to consider rather their traits. 2. THe MECHANISM OF THE INHERITANCE OF CHARACTERISTICS That traits are inherited has been known since man be- came a sentient being. That children are dissimilar com- binations of characteristics has long been recognized. That characteristics have a development in the child is equally obvious; but the mechanism by which they are transmitted in the germ plasm has become known only in recent years. We know that the development of the child is started by the union of two small portions of the germ plasm—the egg from the mother’s side of the house and the sperm from the father’s. We know that the fertilized egg does not contain the organs of the adult and yet it is definitely destined to produce them as though they were there in miniature. The different unit characters, though absent, must be represented in some way; not necessarily each organ by a particle but, in general, the resulting characteristics are determined by chemical substances in the fertilized egg. It is because of certain chemical and physical differences in two fertilized eggs that one develops into an ox and the other into a man. The differences may be called determiners. Determiners are located, then, in the germ cells, and recent studies indicate a considerable probability that — they are to be more precisely located in the nucleus and |: even in the chromatic material of the nucleus. To make this clear a series of diagrams will be necessary. Figure | is a diagram of a cell showing the central nucleus in which runs a deeply staining network—the chromatin. In the division of a cell into two similar daughter cells the THE METHOD OF EUGENICS 11 most striking fact is the exact division of the chromatin (Fig. 2). We know enough to say that the nucleus is the center of the cell’s activity and for reasons that we shall see immediately it is probable that the chromatin is the most active portion of the nucleus. Attraction-sphere enclosing two centrosomes Plastids lying in ( Plasmo- the cytoplasm some or true nucle- olus Chromatin- Nu- network cleus |} Linin-net- —4 work Karyosome, 3 net-knot, or chromatin- nucleolus — Vacuole Passive bodies (metaplasm or paraplasm) sus- pended in the cytoplasmic meshwork T1c. 1.—Diagram of a cell. Its basis consists of a meshwork containing numerous minute granules (microsomes) and traversing a transparent ground substance. From E. B. Witson: ‘‘The Cell in Development and Inheritance.” The fertilization of the egg (Fig. 3) brings together de- terminers from two germ plasms and we know that, on the whole, the two germ cells play an equal réle in carrying determiners. Now the germ cells are of very different size in the female (egg) and the male (sperm). Even the nuclei are different; but the amount of chromatic substance is the same. Hence it seems probable that the chromatic substance is the carrier of the equal determiners. But if determiners from the male are added to those from the female in fertilization it would seem necessary 12 HEREDITY IN RELATION TO EUGENICS Fic. 2.—Diagrams showing a series of stages in the process of division of the chromosomes during cell division. A. Resting cell in which the chromatic material lies (apparently) scattered through the nucleus: at c is a pair of recently divided central bodies (centrosomes) which come to be the centers of the forces that separate the chromosomes. B. The chromatin has fallen into the form of a thick ribbon or sausage-like body, outside of which lies a dark body which is called the ‘‘nucleolus.” The centrosomes are moving apart. C. The centrosomes now lie far apart and the thin membrane around the nucleus is beginning to disappear—a process completed in D, where a “spindle” is seen lying between the two centrosomes. The chromosomes are beginning to move under the influence of the new forces centered at the centrosomes. EF. A later phase in which changes of two sorts are taking place in the chromosomes; first, they are moving to an equatorial position between the two poles, and, secondly, they show their double nature by virtue of which the subsequent THE METHOD OF EUGENICS 13 that the number of these determiners should double in every succeeding generation. There must be some special mechanism to prevent this result. An appropriate mechan- ism is, indeed, ready and had been seen and studied long before its significance was understood; this is the elimina- Fic. 3.—Three stages in the fertilization of the egg of a marine ringed worm (Thalassema). As seen in thin dyed sections. A. At the top of the egg there is occurring a division of the chromosomes that constitutes the ripening or ‘“‘maturation’’ of the egg, illustrated in greater detail in Fig. 4. At the bot- tom a sperm cell (<”) has entered the egg and is penetrating through it toward its center. B. The nucleus of the egg is now returning toward the center to meet that of the sperm. C. The egg and sperm nuclei are now in contact; henceforth they work in unison; fertilization is completed. After GRIFFIN from E. B. Witson: ‘‘The Cell in Development and Inheritance.” tion from both the immature egg and the immature sperm of half of the chromatic material (Fig. 4). Thus if the im- mature sex-cell contains four chromatic bodies (chrom- osomes) each mature sex-cell will contain only two chromo- somes. Moreover, each of the chromosomes in the im- mature sex-cell is double; one half having originated long before in its maternal germ plasm and the other half in its paternal germ plasm. The mechanism for maturation is process of splitting takes place. F. The processes just preceding chromosome division are now completed; the activity of the centers is at its height; the chromosomes now constitute an ‘‘equatorial plate,” e.p. G. The chromosomes at the equatorial plate are now beginning to move apart. H. The separation of the chromosomes is continuing and in J is completed; meanwhile the ac- tivity at the centers has declined and division of the body of the cell is begin- ning. J. Division of the cell completed; the nuclei and centrosomes at the condition with which we started at A. From E. B. Witson: ‘The Cell in Development and Inheritance.” 14 HEREDITY IN KELATION TO EUGENICS Fig. 4.—Diagrams illustrating the process of reduction of the chromosomes by which half of the chromatic material is eliminated from the sex-cell. A. The germ cell is beginning its penultimate division—there are four chromosomes but each of them has already begun to divide to go to their respective poles, as seen at B. C. The last division is taking place, but the four chromosomes do not lie side by side in the equatorial plate as in A, but they unite in two pairs and, in the division, the elements of these pairs are sundered again. Thus out of the original cell four ripe sperm-cells (D) each with only two chromo- somes arise. From E. B. Witson: ‘‘The Cell in Development and Inheritance.” such that either the paternal or maternal component of any chromosome is eliminated in the process, but not both. (Fig. 5). Beyond the condition that one half of each kind of chromosome must go to each daughter cell it seems to be a matter of chance whether the portion that goes to a particular cell be of paternal or of maternal origin. It is even conceivable that one germ cell should have all of its chromosomes of maternal origin while the other cell has all of a paternal origin. > The important point is that the number of chromosomes in the ripe germ cell has become reduced to-half and so it is THE METHOD OF EUGENICS 15 ready to receive an equal half number from the germ cell with which it unites in fertilization. Fic. 5.—Diagram illustrating the mechanism in the chromatic bodies that secures the segregation of determiners. The determiners are assumed to be packed away in the chromosomes. There are equivalent chromosomes (a’ and a”’, b’ and 6b”, ete.) in the nuclei of the male (o’) and female (@) germ cells that unite in the fertilized egg (Fig. 3) and these two sets of chromosomes pass into all the embryonic cells—whether of the soma or germ gland—that develop in the young individual. In the division of ordinary body-cells, as illustrated in Fig. 2, each rod a’, a’’, b’, b’’, etc., splits lengthwise and half of each goes to each daughter cell. But in a division just before the germ cells become ripe, as in Fig. 4C, the like chromosomes unite in pairs as at B. Thus a’ unites with a” to form a; b’ unites with b” to form b; ete. Conse- quently, the number of chromosomes is reduced to half the typical number. When cell-division thereupon occurs (C) and the chromosomes split, either the chromosomal element that was derived from the father (black) or that de- rived from the mother (white) goes, indifferently, to either daughter cell. Consequently, each germ cell contains some chromosomes of maternal and some of paternal origin but not two chromosomes of the same kind. Since, by hypothesis, each chromosome contains particular kinds of determiners it follows that the same germ cell does not contain the (sometimes contrasting) characters of both parents, but some have the paternal character and others the corresponding maternal character. 16 HEREDITY IN RELATION TO EUGENICS 3. Tue Laws or HEREDITY We are now 1m a position to understand the modern laws of heredity. First of all it will be recognized that nothing is inherited except the determiners in the germ cells; the characters themselves, on the contrary, are not directly - inherited. A clear grasp of this fact gives the answer to many questions. Thus the possibility of the transmission of somatic mutilations is seen to depend upon the capacity of such mutilations to modify the determiners in the germ plasm, and such capacity has never been proved. On the other hand, the germ cells receive nutritive and other par- ticles from the blood and they may receive also poisons from it. Hence arises the possibility of depauperization of the germ plasm and of ‘‘race poisons;”’ but these are exceptional and little known phenomena. To understand the way heredity acts, let us take the case where both germ cells that unite to produce the fertilized egg carry the determiner for a unit character, A. Then in the child that develops out of that fertilized egg there is a double stimulus to the development of the unit char- acter A. We say the character is of duplex origin. If, on the other hand, only one germ cell, say the egg, has the. determiner of a character while the other, the sperm, lacks - it, then in the fertilized egg the determiner is simplex and ° the resulting character is of simplex origin. Such a char- acter is often less perfectly developed than the corresponding’ character of duplex origin (Fig. 6). Finally, if neither- germ cell carries the determiner of the character A, it will. be absent in the embryo and the developed child. A per-, , son who shows a character in his body (soma) may or may + not have the determiner for that character in all of the ripe - germ cells he carries, but a person who lacks a given unit > character ordinarily lacks the corresponding determiner ° ' THE METHOD OF EUGENICS 17 (Red i ‘ tral form). ‘ . bea SISCTMCIU ES | ] ancestral form). aa Zygote (First filial generation) tndiviads! . Gametes Tyg Ind . i (Second filial generation) Gam oe 2 (Third filial generation) Fic. 6.—Illustration of laws of inheritance drawn from the crossing of red (a) and white (b) flowered four-o’clocks (Mirabilis jalappa). The offspring of this cross, having the determiner for red from one side only, produced pink flowers only (c). But when these pink-flowered plants were bred together they produced plants of which one in four had red flowers (duplex, d), two in four had pink flowers (simplex, e. f.), while one in four had no red pigment (nulliplex, g). In the lower part of the chart is a diagram showing for each generation the sort of germ cells involved in the union (zygote), the color of the adult, and the nature of the germ-cells he produces; all carried out to the third generation of descendants. From V. HaEcKER: “Wandtafeln zur all- gemeinen Biologie” (Nageli: Leipzig). : 18 HEREDITY IN RELATION TO EUGENICS in all of his germ cells; for, were the determiner present anywhere in his organization (including his germ cells) the corresponding character would ordinarily show in his soma. In connection with the so-called Mendelian analysis of heredity a nomenclature has grown up which is somewhat different from that here employed. Thus the absent char- acter is often called recessive, the present character domi- nant and the condition in the offspring resulting from a this work “absence” does not always imply absolute but only relative absence. Thus the pigmentation of light brown hair is “ absent” to “black,” and “tow” is absent to light brown; but pigment is present in all these grades of hair. To avoid the confusion between relative and absolute ab- sence the terms recessive and dominant are often used to advantage, wherever a series of grades of a character is under consideration. These general principles may be rendered clearer by means of a Table of the different sorts of matings of germ cells. And, to focus attention, let us have in mind a con- crete example; that of pigment of the iris of the human eye. In the following table P stands for the determiner of brown pigment and p for its absence. Six sorts of unions are possible. See also Plate I, frontispiece. TABLE I Laws OF INHERITANCE OF CHARACTERS BASED ON CONDITIONS OF THE DETER- MINERS IN THE PARENTAL GERM PLASMS DETERMINERS Case One parent Other parent Offspring Characteristics of offspring 1 PP PP PP,PP All with pigmented iris (brown-eyed) 2 PP Pp PP, Pp All pigmented, but half sim- plex THE METHOD OF EUGENICS 19 DETERMINERS—continued Case One parent Other parent Offspring Characteristics of offspring 3 PP pp Pp, Pp All pigmented and all simplex 4 Pp Pp PP, Pp, pP, pp 4 duplex pigmented; 14 sim- plex; 14 unpigmented (blue- eyed) 5 Pp pp Pp, pp 14 simplex; 4% unpigmented (blue-eyed) 6 pp pp PP, pp All unpigmented (blue-eyed) In the case of an individual who has received the deter- miner for one of his unit characters from one side of the house only (say from mother), not only is the character simplex, but when the germ cells mature in that person they are of two types, namely, with the determiner and without the determiner; and these two types are equally numerous (Fig. 5). This is the phenomenon known as segregation of presence and absence in the germ cells. If both parents are simplex:in a character, so that they produce an equal number of germ cells with and without the character then in a large number of offspring, 1 in 4 will have the char- acter duplex; 2 in 4 simplex, and 1 in 4 will not have the character at all (nulliplex). This gives in the offspring of such a pair the famous 3 to 1 ratio, sometimes called the Mendelian ratio. Tasie II LAW OF CONDITION OF EYE-CHARACTERS IN CHILDREN BASED ON THE CHARAC- TERS OF THEIR PARENTS One parent Other parent Cases : Offspring brown brown 1, 2,4 Either all of the children have brown eyes, or one fourth have blue eyes brown blue 3, 5 Either all children brown-eyed (though simplex) or half blue-eyed blue blue 6 All blue-eyed Now the foregoing rules, which we have illustrated by the case of eye-color, hold generally for any positive determiner or its unit character. 20 HEREDITY IN RELATION TO EUGENICS 4. INHERITANCE OF MULTIPLE CHARACTERS In the foregoing section we considered the simplest case, namely that in which a single character is taken at a time— i. e., one parent has some character that the other lacks. We have now to consider the cases which are still commoner in nature where the parents differ in respect to two independ- ent characters. Let, for example, the two characters be eye-pigment and hair curliness. Then each one of the six matings given in Table I for eye-color may occur com- bined with any one of the six matings for hair form; so that there would be a total of 6 times 6 or 36 possible combina- tions of matings. Similarly Table II would be replaced by one of 9 entries as follows. Taste III LAW OF COMBINED INHERITANCE OF EYE-COLOR AND HAIR FORM One parent Other parent Offspring Brown eye, curly hair Brown eye, curly hair Either all brown-eyed and curly-haired; or one- fourth blue-eyed and also one-fourth of all straight- haired (with or without blue eyes) Brown eye, curly hair Brown eye, straight hair All (or all but one-fourth) ; brown-eyed, and either all or one-half straight-haired Brown eye, straight hair Brown eye, straight hair All (or all but one-fourth) brown-eyed; all straight- haired Brown eye, curly hair Blue eye, curly hair All (or one-half) brown-eyed; all (or three-fourths) curly- ; haired Brown eye, curly hair Blue eye, straight hair All (or one-half) brown- eyed; all (or one-half) curly-haired Brown eye, straight hair Blue eye, straight hair All (or one-half) brown- eyed; all straight-haired Blue eye, curly hair Blue eye, curly hair All blue-eyed; all (or three- . fourths) curly-haired Blue eye, curly hair Blue eye, straight hair All blue-eyed; all (or one- half) curly-haired Blue eye, straight hair Blue eye, straight hair All blue-eyed; all straight- haired THE METHOD OF EUGENICS 21 The lessons that this enforces are: first, that characters are often and, indeed, usually, inherited independently and, secondly, that the outcome of a particular mating may be predicted with some precision; indeed, in many matings with certainty. This study might be extended to cases of three or more independent characters but the tables in such cases become more complex and little would be gained by making them as the principle has been learned by the cases already given. In view of the great diversity of parents in respect to their visible characters the variability of children is readily accounted for. 5. Herepity or Sex anp or ‘‘SEX-LIMITED”’ CHARACTERS In most species, as in man, there are two sexes, and they are equally numerous. For a long time this equality has been a mystery; but of late years, through the studies of McClung, Wilson, Stevens and Morgan, the mystery has been cleared up. For there has been discovered in the germ plasm a mechanism adequate for bringing about the observed results. We now know that sex is probably determined strictly by the laws of-chance, like the turn of a penny. “The cytological theory of the facts is as follows. One sex, usually (and herein taken as) the female, has all cells, even those of the young ovary, with a pair of each kind of chromosome, of which one pair is usually smaller than the others and more centrally placed. The chromo- somes of this pair are called the X chromosomes. In the male, on the other hand, the forerunners of the sperm cells have one less chromosome, making the number odd. This odd chromosome [exceptionally paired] is usually of small size and is also known as an X chromosome. In the cell- division that leads to the formation of the mature sperm- 22 HEREDITY IN RELATION TO EUGENICS atozoon, this odd chromosome goes in toto to one of the two daughter cells (Fig. 5). The X chromosomes are commonly regarded as the ‘‘sex-chromosomes.”’ With them are asso- ciated various characters that are either secondary sex characters or “‘sex-limited” characters. Consequently in respect to each and every such character the primordial egg cells are duplex and all the ripe eggs have one sex de- terminer and its associated characters. The primordial male cells are simplex and consequently, after segregation has occurred, the spermatozoa are of two equally numerous kinds—with and without the sex-determiner. The fertili-— zation of a number of eggs by a number of sperm will result: in two equally common conditions—namely a fertilized . egg, called zygote, that contains two sex determiners—such - develops into a female; and a zygote that contains only one sex determiner—such develops intoa male. The nature of the germ cells in the germ gland of the future child and of the associated secondary sex-characters thus depend on which of the two sorts of sperm cells go into the make-up of the zygote. Whenever the male parent is characterized by the absence . of some character of which the determiner is typically: lodged in the sex chromosome a remarkable sort of inherit-. ance is to be expected. This is called sex-limited inherit-. ance. The striking feature of this sort of heredity is that the trait appears only in males of the family, is not trans- mitted by them, but is transmitted through normal females of the family. Striking examples of this sort of heredity are considered later in the cases of multiple sclerosis (Fig. 64); atrophy of optic nerve (Fig. 77); color blindness (Fig. 88); myopia (Figs. 90, 91); ichthyosis (Figs. 106, 108); muscular atrophy (Fig. 125); and haemophilia (Fig. 134). The explanation is the same in all cases. The abnormal condition is due to the absence of a determiner from the THE METHOD OF EUGENICS 23 male X chromosome. Its inheritance can be followed from Figure 7, adapted from Wilson, 1911. If the trait be a positive sex-limited one, originating either on the father’s or the mother’s side, its inheritance 9 line 3 line zygotes - gametes . — zygotes XX" Xx gametes zygotes Fig. 7.—Diagram illustrating the method of inheritance in sex limited heredity. X, the sex chromosome, double in the female individual, single in the male. When ripe germ cells are formed in the female, each contains the sex determiner, but in the male half of the germ cells have and half lack the deter- miner (represented by the dash—). Let X’ represent the sex chromosome of the original male that showed the defect (absence of some unit character). Let such a male be mated with a female of an unaffected strain. Then all children will have the determiner for the positive condition (Gen. 2, zygotes, i. e., fertilized eggs and the individuals that develop from them). In the third generation four kinds of zygotes will appear: 1, the normal female who is not capable of transmitting the defect; 2, the normal female who is capable of transmitting the defect; 3, the normal male who is incapable of transmitting the defect; 4, the defective male. Based on E. B. Witson, 1911. will be more irregular; but it can be worked out by the aid of Figure 7. 6. THE APPLICATION OF THE Laws or HEREDITY TO EUGENICS If one is provided with a knowledge of the methods of inheritance of unit characters it might seem to be an easy matter to state how each human trait is inherited and to show how any undesirable condition might be eliminated from the offspring and any wished for character introduced. 24 HEREDITY IN RELATION TO EUGENICS Unfortunately, such a consummation cannot for some time be achieved. The reason for the delay is twofold. First, we do not yet know all of the unit characters in man; second, we can hardly know in advance which of them are due to positive determiners and which to the absence of Such. Unit characters can rarely be recognized by inspection. For example the white coat color of a horse is apparently a simple character, but experimental breeding shows that it is really due to several independently inheritable factors. The popular classification of traits is often crude, lagging far behind scientific knowledge. Thus insanity is frequently referred to a single trait. It is clear, however, that insanity is a result merely and not a specific trait. Some cases of insanity indicate an innate weakness of the nervous system such as leads it to break down under the incidence of heavy stress; other cases of insanity are due to a destruction of a part of the brain by a wound as, for instance, of a bullet. In some cases, through infection a wide-spread deteriora- tion of the brain occurs; in other cases a clot in a cerebral blood vessel may occlude it, cut off nutrition from a single locality of the brain and interfere with movements that have their centres at the affected point. Now these four results cannot be said to be due to the same unit defect; and they can hardly be compared in the study of heredity. On the other hand, the original expectation that progress must wait on'a complete analysis of unit characters proves not to be correct. There are a number of forms of insanity that are sharply separable symptomatically and structurally which have a common basis in that they are due to a nervous weakness; and ‘‘nervous weakness” may behave in heredity with relation to ‘‘nervous strength” like a lower grade, or the absence, of a highly developed character. Even with- out a complete analysis of a trait into its units we may still make practically important studies by using the principle THE METHOD OF EUGENICS 25 that when both parents have low grades of a trait-complex the children will have low grades of that complex. The matter of dependence of a character on a determiner or its absence is of great importance and is not easy to anti- cipate. For instance, long hair as in angora cats, sheep or guinea pigs is apparently not due to a factor added to short hair but rather to the absence of the determiner that stops growth in short-haired animals. One can only conclude whether a character is due to a determiner or to its absence by noting the effect of breeding likes in respect to the given trait. If all offspring are like the parents in respect to a trait, the trait (if simple) is probably a negative one. But if the offspring are very diverse, the trait (if simple) is probably due to a positive determiner and the germ cells of the parents are of two kinds; some with and some without the deter- miner. The determination of unit characters is complicated by the fact that a character due to a simplex determiner often differs from one due to a duplex determiner. In the former case the character is slow in developing and frequently fails of reaching a stage of development found in the latter case. The offspring of red and black-eyed birds may have at first a light iris which gradually darkens. This fact is spoken of as the imperfection of dominance in the simplex condition. Despite the difficulties in analysis of units of heredity and despite the complications in characters it is possible to see clearly the method of inheritance of a great number of human traits and to predict that many more will become analyzed in the near future. CHAPTER III THE INHERITANCE OF FAMILY TRAITS Before any advice can be given to young persons about the marriage that would secure to them the healthiest, strongest children it will be necessary to know not only the peculiarities of their germ plasms but also the way in which various characters are inherited. The work of the student of eugenics is, consequently, to discover the methods of inheritance of each characteristic or trait. After we get precise knowledge of the methods of inheritance of the commoner important traits we shall be in a position to advise, at least in respect to these traits. It would seem'a self evident proposition, but it is one too little regarded, that knowledge should precede teaching. In this chapter an attempt will be made to consider many of the traits that are known to run in families and to set forth, so far as known, the laws of their inheritance. We shall begin with some of the general characteristics of man that have been best studied and then pass to a consideration of some human diseases. In the study of many of these traits I have made use of data that have been furnished by numerous collaborators, chiefly on questionaires know as “‘ Family Records.” These are frequently referred to in the following pages, but always anonymously. The Family Records or “ Records of Family Traits,” as they are also called, are largely derived from professional circles, but not a few from farmers and business 26 THE INHERITANCE OF FAMILY TRAITS 27 men. In respect of several of the special abilities the collaborators have voluteered a numerical grading as follows: 1, poor; 2, medium; 8, exceptionally good. These grades are frequently referred to below. 1. Eye Cotor This depends upon the condition of pigmentation of the iris—the colored ring around the pupil. According to Mr. Charles Roberts (1878, p. 134)! the iris has on its inner surface ‘“‘a layer of dark purple called the uvea . . . and in brown eyes there is an additional layer of yellow (and, perhaps, brown-red) pigment on its outer surface also, and in some instances there is a deposit of pigment amongst the fibrous structures. In the albino, where the pigment is entirely absent from both surfaces of the iris, the bright red blood is seen through the semi-transparent fibrous tissue of a pink color; and in. blue eyes, where the outer layer of pigment is wanting, the various shades are due to the dark inner layer of pigment—the uvea—showing through fibrous structures of different densities or degrees of opacity. “The eyes of new born infants are dark blue, in conse- quence of the greater delicacy and transparency of the fibrous portion of the iris; and as these tissues become thick- ened by use and by advancing age the lighter shades of blue and, finally, gray are produced, the gray, indeed, being chiefly due to the color of the fibrous tissues themselves.” Yellow pigment is laid down upon the blue, forming yellow- blue or green eyes. “In the hazel and brown eyes the wvea and the fibrous tissues are hidden by increasing deposits of yellow and brown pigment on the anterior surface of the iris, and when this is very dense, black eyes are the result.” While in most races of the globe brown pigment is heavily 1 For titles of works referred to in text, see Bibliography, at end of book. 28 HEREDITY IN RELATION TO EUGENICS RELATIVE FREQUENCY BRUNET TRAITS. Fic. 8.—Map of southwestern Europe showing the relative frequency of “brunet traits,” e. g., brown eye color. On the whole, the darker the shade the greater the proportion of brunet persons in the given area. The lightest areas represent about 20 to 25 per cent brunetness; the darkest European areas over 90 per cent brunetness. At the northern limit of the map ‘about one third of the people are pure blonds, characterized by light hair and blue eyes;” on the other hand, in the south of Italy the pure blonds have almost entirely disappeared. From W. Z. Ripuey: “The Races of Europe.”’ THE INHERITANCE OF FAMILY TRAITS 9 PURE BLUE EYES Fig. 9.—Distribution of pure blue eyes among Scottish boys. About 15 per cent of all boys have blue eyes. The relative density is indicated by depth of shading as indicated in the key at the left. A very high density (21 to 24 per cent) occurs in the lower Spey Valley in the northwest. This is the region of the Norse invasion which brought in much protoplasm that was defective in pigmentation. The highest density (over 24 per cent) exists in the coal and iron districts of East Lanarkshire and ‘‘this is probably due to the Irish immi- grants.” J. Gray, 1907. 30 HEREDITY IN RELATION TO EUGENICS secreted in the iris, in northwestern Europe blue, gray or yellow-blue eyes are found. It seems probable that, once upon a time, or perhaps at many times, an individual was born without brown pigment in the iris. The offspring of such prospered and spread throughout northwestern Europe and migrated thence to America and Australia (Fig. 8). This defect, lack of eye pigment, has had a wonderful history. By noting its distribution the migrations of peoples can be traced. Thus Gray (1907) has shown that, in Scot- land, pure blue eyes are most abundant in the coal and iron districts. ‘‘This is probably due to the Irish immi- grants, it being well known that blue eyes are very common among the Irish.”” In the Spey valley of Scotland the dens- ity of pure blue eyes is high—probably owing to the Norse invasion at that point. (Fig. 9). So in our country the pigmentation survey that will some day be made will show a high percentage of blue eyes where the Scandinavians and north Germans have settled. Thus eye color, just because it shows no tendency to blend in heredity, is a most valuable aid in history. Our knowledge of heredity of eye color depends on studies made by Galton, 1899, who noted its alternative nature but otherwise overlooked the true method of its inheritance; more recently, by three studies car- ried on simultaneously and independently and published by G. C. and C. B. Davenport, in November, 1907; by C. C. Hifrst in 1908; and by Holmes and Loomis in December, 1909. Since 1907 the present author has collected additional data. Hurst’s data have the advantage of having been collected from personal observation, hence the chance of error due to a diversity of collaborators was eliminated. In the other studies the data were supplied by unprejudiced, if not always critical, recorders. Applying the test of the 6 (strictly 5) kinds of unions we get the results shown in Table IV. THE INHERITANCE OF FAMILY TRAITS 31 Taste IV Daven- |HoLmEs & . Horst pera Loainia Tora | P’ortion One Parent Other Parent | Blue |Pig’t |Blue |Pig’t | Blue Pig'| Bru Pig't|Blue Pig’t pure blue pure blue 101 0| 77) of 51] 1| 229] 1199.5] 0.5 pigmented (Pp) blue 137] 121] 428] 506 89} 85} 654/712/48.0| 52.0 pigmented (PP) blue 0) 66 0 R 70 0/136) 0 {100 pigmented (Pp) pigmented (Pp) 18] 45] 987/'169 5] 34] 121|248|33 67 pigmented (PP) pigmented (Pp) 0} 195 0} 99 0|294/; 0 /|100 Table IV supports the following conclusions: 1. When both parents have pure blue eyes all of the chil- dren will have pure blue eyes (the discordant case is prob- ably due to an error). 2. When one parent has pigmented iris while the other has blue, either the fraternity of children will show no blue eyes or else half of them will be blue-eyed. The sum of the latter class, the second case, gives 654:712 or 48 per cent to 52 per cent. 3. When both parents have brown iris either all the children will have brown iris (last case in Table IV) or else about a quarter will lack brown pigment and so will be blue-eyed. The eugenic value of the inheritance of eye color lies in the consideration, advanced by Major Woodruff, that pig- mentation of the eye, skin, etc., better fits a child for life in the tropics or in a country, like the United States, of bright sunlight. Brown-eyed children can be secured from blue-eyed stock by mating with pure brown-eyed stock. We have heard of two blue-eyed parents regretting that they had no brown-eyed children. They wished for the impossible. 1 Eight hundred and sixty-six additional cases collected subsequently are not included be- cause unchecked. 2A number of these blues are doubtless destined to become pigmented in later life. 32 HEREDITY IN RELATION TO EUGENICS 2. Harr CoLtor This character is due to the presence of brown granules in the hair and sometimes also to the presence of a diffuse reddish pigment. The study of heredity of hair color is complicated—more than that of eye color—by the fact that the hair grows darker with age, at least until maturity is achieved. If you compare the light browns and the blacks in children under 16 and over 16 you will find twice as many light browns in the younger lot as in the older; but only half as many blacks. In other words, half of the persons who will eventually have black hair still have light to medium brown at 16 years of age.1_ While this tends to obscure the result yet the general fact of segregation in hair color cannot be gainsaid. Let us examine the results of various matings. (Table V). TasBLe V THE HAIR-COLOR OF THE OFFSPRING OF PARENTS WITH DIFFERENT CLASSES OF HAIR PIGMENT. One parent Other parent Offspring -Little brown Little | brown All with tow, yellow, golden or red hair. pigment pigment : Brown pig- Little or no Half with light hair, half with brown; in ment brown pigment other families all children may eventually . gain brown hair Brown pig- Brown pigment Most children have brown hair; some (about ment one-quarter) have light hair. In some families all children eventually gain brown hair. The most striking result is that dark-haired children prob- ably never come from flaxen-haired parents. Indeed, a good practical rule is that the children will not acquire hair darker than that of the darker parent. The inheritance of red-hair color has a certain eugenic importance. There can be little doubt that a young person 1 Holmes and Loomis, 1909, p. 55. THE INHERITANCE OF FAMILY TRAITS 33 Fic. 10.—Wavy hair; a Segumbar, female, Philippine Islands. (Lent. by the American Museum of Natural History.) 4 Fi who has red hair has a strong ‘antipathy ‘to a red-haired person of the opposite sex. This testimony comes to me from the father of a red-haired daughter. It is confirmed by the fact that, despite prolonged inquiry among thousands of families I have succeeded in obtaining only two cases where both parents had red hair. Though the red was not a clear red in all parents all of the 8 children had red hair. If one parent only forms ‘‘red-hair” germ cells ex- clusively while the other forms exclusively germ cells con- taining the determiner for black pigment the offspring will show no red; still less will red-haired offspring appear if neither parent forms ‘‘red-hair”’ germ cells. Red-haired offspring may come from two brown or better from glossy black-haired parents provided both form red-hair germ cells. In that case both dark-haired parents will probably 34 HEREDITY IN RELATION TO EUGENICS Fra. 11.—Frizzy or kinky hair; a Soudanese male. (Lent by the American Museum of Natural History from a photograph in the Philadelphia Museum.) have ancestors or other close relatives with red hair. Glossy black hair in the parents is especially apt to produce red hair in the children because the glossiness is usually due to red hidden by black pigment. 3. Harr Form The form of the hair varies from straight through wavy and curly (Fig. 10) to kinky (Fig. 11) and woolly (Fig. 12), depending largely upon the closeness of the spiral. These different types of hair have a different form on cross-section; 7. é., the cut end of,a straight hair is nearly circular while THE INHERITANCE OF FAMILY TRAITS 35 Fie. 12.—Woolly hair; a Congo negro. (Lent by American Museum Natural History.) that of woolly hair is much flattened, being only half as thick as it is broad. Both the flattening and the curving of hair are due to a modification of the cup or “‘hair follicle” in which the hair develops. Thus, while straight hair devel- ops in a plain, cylindrical follicle that of the flattened types is curved and inclined in relation to the surface of the skin. Straight hair is the simple condition; curving is due to a special modification. What, now, is the method of inherit- ance of this special modification? First, if both parents have hair that from childhood up has been straight, without natural tendency toward curving, then all of the children will have straight hair. There are exceptional cases reported of wavy haired children from straight haired parents, but the exceptions constitute less than 2 per cent. 36 HEREDITY IN RELATION TO EUGENICS If one parent has wavy hair while the other has straight hair then, since in wavy haired persons half the germ cells are without the determiner for curved hair, half of the off- spring will have straight and half curved hair. If both parents have wavy (simplex) hair about 75 per cent of the children will have curved hair and the others straight hair. But two curly haired parents, both of curly haired stock on both sides, will probably have all curly or wavy haired children. In a word, when either of the germ cells that unite to form the fertilized egg contains the curly determiner the offspring will have curved hair. 4. Skin CoLor The pigment of the skin is due to brown granules lying in the deep stratum of the skin. Such granules occur in most people, are common in brunets and still more abundant in negroes. Besides the brown granules a yellow-red pig- ment is present, but this has been little studied. Now when both parents are clearly blonds most, if not all, of their offspring are blonds. In 513 offspring reported as derived from this sort of mating 91.4 per cent are recorded as blonds and 6.8 per cent as intermediate, while only 1.8 per cent are stated to be brunet—quite within the limit of error due to inaccuracy of the collaborators. If one person is blond and the other darker, about half of the children will, on the average, be blond and half pigmented but rarely darker than the darker parent. If both parents be dark the percentage of brunets ranges from about 25 to zero. In general, whatever the mating, the children will not be darker than their darker parent. When one parent is white and the other as dark as a full- blooded negro the offspring are, as is well known, of an intermediate shade (mulatto, mezzotint). If two such mulattoes marry their offspring vary in color. In one fra- THE INHERITANCE OF FAMILY TRAITS 37 ternity derived from two such mulattoes having 45 per cent and 13 per cent respectively of black in the skin, the proportion of black in the 7 offspring whose color was measured ranged from 46 to 6 (Fig. 13). The lighter limit was as light as most Caucasian skins. In another fraternity whose parents had 29 per cent and 13 per cent of black respectively, the children ranged from 28 per cent to 8.5 per cent of black in the skin color.! “ Here, again, the light- W. Famity 3 (white) = 9 (negro) 3 (mulatto) = 9 (mulatto) $ (mulatto; = 9 (mulatto; color ¢ (mulatto) = 9 (mulatto) “color of of 12-year old grand- son’’) daughter) 3 (mulatto ;= 9 (mulatto, “very dark’’; 13-17-35-35) | 45-12-83-10) : ! | I I UJ ! t 3 3 g 3 2 é é é 2 19 yrs. 17 yrs. 15 yrs, 13 yrs. 12yre. 10 yrs, Syrs. Tyrs, 5Syrs. 32 46 31 6 23 absent; ‘‘color of N 25 33 color of father’? ‘Y 20 14 7 15 4 17 16 12-year absent R 30 37 40 30 30 35 28 ee sis- W25 17 7 24 60 25 33 r ‘ Fig. 13.—Pedigree chart of ‘‘W” family of mulattoes, showing the percent- ages of the four colors; black (NV), yellow (Y), red (R) and white (W) that combined (as in the color wheel) will give the skin color.’, male; 9, female. For fuller details see Davenport, G. C., and C. B., 1910. est child has practically a white skin. In the case of the two other families, in which the parents were dark mulat- toes (80 to 40 per cent black) none of the children were lighter than 27 per cent black. The germ cells of the parents ‘probably lack the lower grades of pigmentation. On the other hand two very light “colored” parents will have (probably) only light children, some of whom ‘“‘pass for whites” away from home. So far as skin color goes they are as truly white as their greatgrandparent and it is quite 1 All colors were determined by means of the Bradley color top. 38 HEREDITY IN RELATION TO EUGENICS conceivable that they might have mental and moral qual- ities as good and typically Caucasian as he had. Just as perfect white skin color can be extracted from the hybrid, so may other Caucasian physical and mental qualities be extracted and a typical Caucasian arise out of the mixture. However, this result will occur only in the third, or later, hybrid generation and the event will not be very common. Albinism. This is an extreme case of blondness—all pigment being lost from skin, hair and eyes. The method. of inheritance resembles that of eye color. When both parents lack pigment all offspring are likewise devoid of pigment. When one parent only is an albino and the other is unrelated the children are all pigmented. Whenever albinos occur from two normals the proportion of these albinos approaches the ideal and expected condition of 25 per cent (Fig. 14). Albinism is not a desirable peculiarity, despite the beauty of complexion and hair, because the lack of pigment in the retina makes it hard to bear strong light. Albinos may avoid transmitting albinism by marrying unrelated, pig- mented persons. Pigmented persons belonging to albinic strains must avoid marrying cousins, even pigmented ones, because both parents might, in that case, have albinic germ cells and produce one child in four albinic. Albino com- munities, of which there are several in the United States are inbred communities; but not all inbred communities contain albinos.! 5. STATURE The inheritance of stature has long been a subject of study. It has great interest both because it is easily deter- mined and because it has a great racial range, namely, This matter is discussed more fully in the “ American Naturalist,” Decem- ber, 1910. *xes WMOUUN ‘O ‘eeu ‘9 ‘afeuray é songs peechadsss SapItd HOV [Ty ‘AjunuruI09 posqut ATGSTY sIq} Ul seuIvUIMs UOUTUIOD Ano} OY} Jueserder ‘yy ‘Bf ‘gq ‘g_ S19}}9[ OY, ‘A[fure} ouIg[e ue jo 4189 aa13Ip9g—'FI “D1 Ker X Jelelexeye) Ciorer Y oe OCOD QOK%GO = on pee 9 9°56 0% noe x ® Pa Si) ob Cc S apis Bae a 0'0'e ®@ © »® ocak oes Sal pb wb ; ADs of. een “ee "hy i 29999996 40 HEREDITY IN RELATION TO EUGENICS from 138 centimeters (or 54 inches) in the negrilloes of Africa to 180 centimeters (or 71 inches) in the Scotch. Among European males, stature ranges from 150 centimeters (60 inches) to 190 centimeters (75 inches), while that of women rarely exceeds 180 centimeters (71 inches).! The importance of stature as a definite character is seen in its distribution in Europe. Apart from the variations ascribed to environment there are clear racial (7. e., inherit- STATURE *»= HEALT _ BAPROF INISTERRE ec { PER THOUSAND REJECTED FOR Fic. 15.—Two maps of Brittany, France. On the left is shown the dis- tribution of the various mean statures ranging from 1.62 meters to 1.64 meters. On the right is shown the distribution of rejection of recruits for constitutional defects. Riper: ‘‘The Races of Europe.” able) differences. The rugged hills of Scotland harbor a race that are, relatively, giants; the mild and productive shores of the Gulf of Tarent, Southern Italy, hardly more populous, are inhabited by a people that are, relatively, dwarfs. Conditions of life cannot account for the difference; there is a difference of blood. It is easy to go astray in assigning environmental causes for stature. Thus Ripley (1900, p. 85) referring to a map of Brittany says: ‘‘In the interior cantons, shorter on the average by an inch than the population along the sea coast, there is a corresponding 1 Deniker, ‘Races of Man,” p. 584. THE INHERITANCE OF FAMILY TRAITS 41 increase of defective or degenerate constitutional types. The character of the environment is largely responsible for this.” (Fig. 15). Two maps are given of this territory showing the practical coincidence of the areas of shortest stature and greatest number of rejections of recruits for physical defects. Fifteen pages later, however, practically the same map is used (Fig. 16), the greater height of the 8 Sy EASTERN BOUNDARY oF CELTIC SPEECH PERCENT UNDER, LS6 Meters GFT [pus) 1-4 [j+-6 EB o-e El 6-10 STA URE Mice 1 OWER BRITTANY HHBI214 aster Broca » (1850-59) Bu Fic. 16.—Map of stature in Brittany showing smaller proportion of men whose stature is under 1.56 meters in the region subject to Teutonic invasions. Riper: ‘The Races of Europe.” coastal people referred to, and explained by Teutonic inva- sions. ‘‘The result has been to infuse a new racial element into all the border populations in Brittany, while the ori- ginal physical traits remain in undisturbed possession of the interior.”” It appears, then, probable that the greater rejection of recruits in the central country is due less to its unfavorable environment than to its inadequate blood. Recognizing the inheritable nature of stature it remains 42 HEREDITY IN RELATION TO EUGENICS to inquire how it is inherited. First of all it must be con- ceded that stature is hardly a single unit. It is composed of three elements that would seem to be unrelated, namely, the height of the cranium, the length of the neck and trunk, and the length of the legs. Sitting height is a more signi- ficant measure from the standpoint of heredity; but, unfor- tunately, few persons know their sitting height. A second complication is dependence of stature on age. It increases up to 20 years in the male and about 19 years in the fe- male. Beyond these ages the increase may be neglected. A third complication is that stature is, to a certain degree, dependent on sex. To transmute female measurements to corresponding male measurements Galton (1889) used the method of multiplying them by 1.08 since the mean of male stature is that much greater than the mean of female stature. We can avoid this complication by using, in place of the absolute or transmuted measures, the deviation in each sex from its own mean. The mean stature for the adult males of the white population of the United States may be taken at 69 inches (175 cm); that of females at 64 inches (163 cm). Despite all these complications, which tend to obscure the result, we can still seek an answer to the question: What general laws are there of inheritance of stature? The first general law is that, in case the four grandparents are very unlike, the adult children will vary greatly in stature, whereas when the grandparental statures are closely alike those of the children will be also. This is shown in the following Table: Inches Difference between the shortest and the tallest child: 3 4 5 6 7 8 Difference between the shortest and the tallest grandparent: 4.6 5.0 6.0 6.5 6.9 7.2 This law seems to indicate that the reason why in some THE INHERITANCE OF FAMILY TRAITS 43 families the children vary greatly in stature while in others they vary little is because more diverse elements have entered into the make-up of the children in the first case than in the second. In the first case long and short blood are commingled in the ancestry while in the second case exclu- sively long or exclusively short ancestry as the case may be. The second general law is that when both parents are tall all of the children tend to be tall; but, on the contrary, if both parents are short some of the children will be short and some tall in ratios varying from 1:1 up to 2:1. If all of the grandparents are short then there tend to be twice as many short children as tall; but if one grandparent on each side be tall there will tend to be an equality of short and tall offspring. The evidence for the foregoing is found in the study of 104 families which furnished quantitative data as to stature for children, parents and grand- parents. To illustrate the inheritance of extreme short stature in a family I may quote from C. F. Swift (1888). He says (p. 478) “T am unable to give a particular account of the Little Hatches of Falmouth. [Mass.] They were children of Barna- bas, who married in 1776 his relative Abigail Hatch and had two sons and seven daughters. Six daughters were less than 4 feet in height. None married. The seventh daughter Rebecca was of common size and married Robert Hammond. The two sons, Barnabas, born in 1788, and Robinson, b. 1790, were both of low stature, one, scarce 4 feet in height, was a portly gentleman almost as broad as long.” It may be pre- dicted that the tall daughter who married had only tall chil- dren. 6. TotaL Bopy WricuHtT Adult weight (assuming density to be constant) depends upon stature and circumference. It is, therefore, still more 44 HEREDITY IN RELATION TO EUGENICS complicated than stature and still further removed from any semblance of a unit character. Moreover, it is much more dependent upon conditions of life, for, as is well known, a sedentary life with overfeeding and drinking tends, in persons so disposed, to increase weight, even as strenuous activity and dieting favor the reduction, within certain limits, of weight. Despite this dependence of weight on environment we may attempt to learn if it shows any trace of heredity. First, it is necessary to avoid the use of absolute weights on account of sex differences. So we find the mean weight of American fathers and mothers and calculate our weights as deviations from these means. The mean weight of fathers in our data is 162 pounds; of mothers 131 pounds. The range in weight of fathers is from 110 to 250 pounds. The range in weight of mothers is from 90 pounds to 360 pounds.! In our study we are, however, concerned less with absolute deviations in weight from the average than in the deviations in corpulency and so we make our starting point the weight for a given stature and calculate in each case the deviation from the weight that is normal for the given stature. The table of normal weight that we employ is Table VI. Taste VI NORMAL WEIGHT, IN POUNDS, FOR EACH INCH OF STATURE AND EACH SEX ’ Inches of stature 59 60 61 62 63 64 65 66 67 Normal weight in } male 131 1382 134 137 140 143 147 152 pounds for female 107 112 117 122 126 131 186 13y 141 Inches of stature 68 69 70 71 72 73 74 75 Normal weight in | male 157 162 167 172 177 182 190 198 pounds for | female 144 150 155 160 165 170 The first result is that when both parents are slender in build or of relatively light weight the children will tend all to be slender. ? This maximum occurred in a single case of our records; the next lower weight is 225 pounds. THE INHERITANCE OF FAMILY TRAITS 45 The evidence for this has never been fully set forth. It rests on five fraternities in which the ten parents diverged (in pounds) from the nor- mal as follows: 1, 1, -2, -7, -7, -9, -11, -12, -33, -47. Every grand- parent was below normal in weight except one who was just normal. Of 23 children only 3 are above normal. Their total excess weight amounts to 25 pounds, while the total deficiency of the 20 remaining children is 374 pounds—an average deficiency for the 23 children of 15 pounds. Truly, a slender population. If both parents are heavy and of heavy ancestry their children tend, on the whole, to be heavy (Fig. 17). Stine +50 |+ 50 v.corp. stout +48 +50 stout Fic. 17.—Pedigree of family with corpulency. Great-grandparents, grandparents and one of the parents are much above normal weight for their stature and the same tendency is found throughout the fraternities to which they belong. The father is slender. His daughter is, at an early age, inclined to stoutness. F. R.; Hal. 3. I have data on four families that meet these conditions and give in Table VII all the data concerning their deviations in weight from the nor- mal. TaBLe VII THE DEVIATIONS FROM NORMAL STOUTNESS (WEIGHT-+-STATURE) OF THE AN- CESTORS AND CHILDREN WHEN BOTH PARENTS ARE HEAVY Reference letters FF FM MF MM F M C! @ C3 C4 C8 CE Ave.—2 23 25 24 28 27 35 —10 —6 23 Gan.—1 1 23 3 9 18 21 —6 8 8 9 13 18 Eld.—1 8 11 21 33 33 «5 —12 32 388 53 Elt.—1 3 11 3 44 8 18 —22 —2 C, child; F, father or father’s; M, mother or mother’s. 46 HEREDITY IN RELATION TO EUGENICS It is to be kept in mind that the children are mostly young, 18 to 25, and consequently do not show their potentialities in weight. Neverthe- less, while there are 6 children below the normal in weight, giving a de- ficiency of 58 pounds, there are 9 above the normal with an excess of 202 pounds. When both parents are heavy (disregarding grandparents) the numbers of light and heavy children are practically equal (39 light to 34 heavy or 465 pounds total deficiency to 490 pounds total excess). When one of the parents is heavy and the other slender both heavy and slight offspring occur and, in youth at least, the slight are more numerous than the heavy. Table VIII gives the data on this mating. Taste VIII THE DEVIATIONS FROM NORMAL STOUTNESS (WEIGHT + STATURE) OF THE ANCESTORS AND CHILDREN IN SIX FAMILIES WITH ONE SLENDER AND ONE HEAVY PARENT Reference letters FF FM MF MM F M Ct C@ C? C4 Ci C8 Bab. 21 44 —32 29 10—7—10 —6 23 Bra.—3 —2 —6 8 44 —17 9— 8—16—16—33 7 7 Cro.—2 3 33 —43 3 58—26 38— 7—17—25 8 —28 Elk.—1 8 48 —20 2 33—14—13 —26 —10 —13 How.—_l1 —32 —17 63 78 —45 78 —27 —26 —10 —12 19 Ran.—1 17 —11 —40 44 13—17— 4 In Table VIII are included 27 children, 7 above the normal stoutness and 20 below, ora total of 30 pounds excess to 324 pounds deficiency. A pedigree of a family with hereditary obesity is described by Rose (1907). A girl of 15 with a stature of 145 centi- meters (57 inches) weighed 75 kilograms (165 pounds). The father and his parents were not obese.!_ The mother, on the other hand weighed 88 kilograms and her father 99 kilograms, while the mother’s mother is slender. Of the four children 1 There is no evidence that they did not carry the factor that favors obesity or that they were wholly unrelated to the maternal side. THE INHERITANCE OF FAMILY TRAITS 47 two (including the girl of 15) are very obese, one normal and one under weight. This result accords with the hypothesis that obesity is due to a defect. It is noted that the mother’s mother had a goitre; and it is probable that in this family there is an hereditary deficiency in growth control. not obese —not obesec” o wt. 275 Ibs. — not obese 9 has goitre | roe g slender wt. 180 to 240 lbs. [ | | C,large 9, large at 16—@ 9 , slender 9, at 15 wt. 160 Io 75 kilos I | liner —1il simple meningitis obese, at 15 months, 36 lbs. slender Longevity. When Dr. O. W. Holmes was asked for specifi- cations for a long life he advised, in effect, first to select long- lived grandparents. This advice accords with a widespread opinion that longevity is inheritable. But length of life is not aunit character. It isa resultant of many factors; especially $51 [$82 PTTL bd all but one lived to 70 or over +O +70 UW Fie. 18.—A short pedigree (early 19th century in United States) illustrat- ing ‘‘inheritance’’ of longevity. F. R.; Att. 1. of those factors that resist causes of death. Such factors are absence of defects of bodily structure, resistance to the com- moner virulent germs of disease, and environmental conditions that maintain at its highest point internal resistance. The first two factors are “‘inheritable” and the last remains tolerably 48 HEREDITY IN RELATION TO EUGENICS uniform for the people of a certain social class such as the members of one and the same family belong to; so it is not strange that some families with perfect structure and high resistance should be long lived (Fig. 18) and others, with organic defects and low resistance, should be short lived O r-O Bh t50 eo t72 appendicitis a heart disease $42 +44 defective ortvaivesl ¢ tuberculosis BiG (El eit), Fig. 19.—Fragment of pedigree of a high class family with slight longevity due in part to heart defects and non-resistance to tuberculosis. The latest generation comprises only young children. F. R.; Pyn. 1. (Fig. 19). Thus, while longevity is not a biological unit of inheritance a person belonging to a long lived family is a better ‘‘risk’’ for-a life insurance company than a person belonging to a short lived family. 7. Musicaut ABILITY This quality is one that develops so early in the most marked cases that its innateness cannot be questioned. A Bach, matured at 22; a Beethoven, publishing his composi- tions at 13 and a Mendelssohn at 15; a Mozart, composing at 5 years, are the product of a peculiar protoplasm of whose tenacious qualities we get some notion when we learn that the Bach family comprised 20 eminent musicians and two score others less eminent. The exact method of inheritance of musical ability has not been sufficiently analyzed. Hurst (1908) suggests that it behaves as a recessive, as though it depended on the absence of something. The ‘Family Records” afford some data on this subject. A statement of the grade of musical ability of each person, whether poor, THE INHERITANCE OF FAMILY TRAITS 49. 1 2 3 4: Fie. 20.—Pedigree of an American family of singers. Numbers below symbols designate grades; thus: 1, little or no musical ability; 2, medium ability; 3, exceptionally high ability. Numbers above the individual symbols are for reference. I, 1. Extremely fond of music, had organ and piano in his home; a very cultivated man of artistic tastes. Married I, 2, non-musical, belonging to an utterly non-musical family. Their son, II, 2, is not musical. I, 3. Fond of music, could ‘‘carry a tune” easily. A mathematician and astronomer. His wife, I, 4, was sufficiently musical to sing in such a simple church choir as was to be found in the State of Maine in the middle of the nineteenth century and her mother and mother’s sisters were singers. All of their four children were musical. One son, II, 7, who died unmarried had a fine voice and was a good singer. The other son, II, 4, had a musical ear and a fine voice; he sang much without having taken lessons. His wife is non- musical and their 14-year old daughter is as non-musical as her mother. One of the daughters, IT, 5, had a fine voice and still keeps up her music; she mar- ried an utterly non-musical man and they have one son who cannot even “carry a tune” and one daughter who is a famous opera singer. The other daughter, II, 3,|is a fine singer, and plays the piano, organ and guitar. She married the above-mentioned non-musical man, JI, 2. They had six children all of whom have fine voices; ITI, 1, has a fair baritone voice; III, 2, has an unusually deep bass voice; III, 3, died at 27 years. Her voice was said by good judges, such as the De Reszkes, Anton Seidl, etc., to be more beautiful even than that of III, 8. III, 4, is organist and choir master in a large church in New York City. III, 5, is very musical; ITI, 6, died young but had already developed much musical talent and could read music with wonderful ease. F. R.; H. medium or exceptionally good was asked for. Altogether data were obtained for 1008 children, their parents and most of their grandparents. The following rules are deduced from these data. When both parents are exceptionally good in music 50 HEREDITY IN RELATION TO EUGENICS (whether vocal or instrumental) all the children are medium to exceptionally good. There were 48 cases where both parents showed exceptional musical ability. Of the 202 children 81 had exceptional ability and 120 fair musi- cal ability. Only one is returned as being poor in music; and this case may be cast aside as quite within the probability of an error due to care- lessness in making the returns or to bad classification. These results come out so smoothly as to indicate that high attainment in vocal and instru- mental music are due to the same defect in the protoplasm. Fig. 21.—Pedigree of singing ability and peculiar form of toes. I, 7. (X) has bones of both fifth toes cartilaginous and toe crossed over upon fourth toe; and her granddaughter III, 7, has exactly the same peculiarity; II, 12, has an exceptionally good bass voice; his daughter ITI, 6, cannot sing; but III, 7, has a beautiful soprano voice; III, 8, has an exceptionally good baritone voice; III, 9, has a‘ beautiful contralto voice’ and III, 10, has great musical ability. On the other side of the house, III, 1, has good musical ability. But in the fourth generation there is no musical ability. F.R.; Ait. 1. To illustrate inheritance of musical ability by a concrete °* example the pedigree of a noted New England singer is ap- pended (Fig. 20). This particular example alone could not be used to demonstrate either the hypothesis that musical ability is due to a new unit or that it is due to a defect. When both parents are poor in musical ability and come of ancestry that lacks on one or both sides such ability the children will all be non-musical. Four families of this sort are given in the Records. All 29 children are poor in music. Compare Fig. 21. THE INHERITANCE OF FAMILY TRAITS 51 When one parent has high musical ability and the other has little the children will vary much in this respect. Thus of 257 offspring of such matings 45 are without musical ability, 84 are exceptionally good at music while 128 are intermediate. The re- sult indicates a partial blend in the musical ability of the offspring of mixed origin. As an example that illustrates the law approximately may be cited the Hutchinson family (Hutchinson, 1876). Ac- cording to the statement of Wm. Lloyd Garrison, Jesse and Mary L. Hutchinson, progenitors of the tribe, lived in Milford, N. H., 1777-1863. The father possessed a rare baritone, the mother a sweet and mellow contralto voice. Of the sixteen children, three died young. The remaining thirteen are described as follows: David, deep bass voice; Noah, tenor voice; Andrew, baritone and bass voice, deeply interested in music; Zephaniah, passionately fond of music; Cabel, baritone voice; Joshua, very musical, sang; Jesse, editorial work; Benjamin, not gifted musically; Judson, musical genius; Rhoda, high contralto; John, most command- ing vocal talents of all; Asa, inherited a large share of musi- cal gift; Abbe, contralto voice, one of quartette. Details are lacking concerning the voice of Jesse, and the description of Benjamin is all too vague, considering the importance of this case, and so too much emphasis cannot be laid on these two ‘eases; but aside from them the uniformity of testimony as to vocal talent of the family is striking. 8. ABILITY IN ARTISTIC COMPOSITION Like musical ability, artistic talent shows itself so early as to demonstrate its innateness. Thus extraordinary talent was recognized in Francesco Mazzuoli (though ill taught) at 16, in Paul Potter at 15, in Jacob Ruysdael at 14, in Titian Vecelli at 13. Galton gives the following pedigree of the Vecellis. All the persons named were painters. ‘‘The con- f 52 HEREDITY IN RELATION TO EUGENICS necting links indicated by crosses are, singularly enough, every one of them lawyers” (Fig. 22). x [ | x x | : | | x x x | | | | | x Francisco Titian Fabricio Cesare | | a a ee Marco x Pomponio Horatio Tizianello Tomasco Fia. 22.—Pedigree of the painter family Vecelli.x, father (always a lawyer).— Gatton, 1869. The data furnished by the Family Records seem to justify the following conclusions. When both parents have exceptional artistic ability their children will, in most cases, all have high artistic ability (Fig. 23). The data for this generalization are sparse. Four matings of this sort furnished 13 children of whom 10 had a high grade, 1 is recorded as medium and two as poor; but both of the latter occur in one record that gives in- ternal evidence that the question was not clearly understood. When both parents are devoid of artistic talent and come from an unartistic ancestry none of the children show exceptional ability in art. From 103 such matings (grade 1) there were derived 391 children of whom 185 are given as of grade 1 and 206 as of grade 2, while to none was ascribed grade 3. When one parent is artistic and the other neither himself artistic nor of artistic ancestry then probably none of the THE INHERITANCE OF FAMILY TRAITS 53 Z Car), 2children in ; 5 of eo Fic. 23.—Pedigree of artistic ability (solid black for high talent, oblique shading for talent of a less degree). The family shows also the traits of taste for history (dots), of mechanical talent (vertical lines), and of wood carving (horizontal lines). II, 3, Nathan P, had son Wm. F. (III, 2) who was grand- father of an artist, V, 3; and a daughter Mary (III, 4) who was the great grandmother of artist J. W. F. (VI, 3). This brother and sister (III, 2, and III, 4) married a brother and sister, (III, 1 and III, 3) and it is in this stock that we first find the inheritance of artistic ability. IV, 4, married John E. F. (IV, 5) a man who through life had a love of historic research. This love of history appeared again in George E. F. (V, 6) who became a journalist and subsequently author of several valuable works on Indian history. In his son (VI, 3) in turn this love of history cropped out, as shown both in his Art History researches and as a painter of Indian history scenes. On his father’s side, the lineage of VI, 3, has been traced back to 1630. No art- istic genius was found in the male line except in V, 6 and VI, 3. His grand- mother (IV, 4) displayed artistic tendencies, painting notable pictures through- out life. We turn now to the mother of VI, 3, and her family. Her great-grandfather, Joel L., II, 5, married Jerusha, sister of Noah Webster, II, 7. Their son Chester’s second son, Edward, IV, 15, a distinguished clergyman married Mary J.8., IV, 16, an educated lady and great lover of art. Their son, V, 11, was editor of the N. Y.‘‘Sun,” educator, Regent of the State of New York and fond of drawing and painting in an amateurish way. Artistic gift exists in his sister Anna and his older son, Kenneth. III, 8, married Rev. 8. P., graduate Andover Theological Seminary, first Presbyterian missionary to Oregon. Their first son, IV, 8, entered, the min- istry and was afterward a physician, also having marked artistic genius. His daughter Florence, V, 8, had marked artistic ability. His sister, IV, 10, was also a natural artist and this talent developed in her children and grand- children to some extent. A brother, IV, 12, was clergyman, author-poet and professor in art. His son, V, 9, was a lawyer. Of children of III, 11-12, IV, 19, was gifted as a wood-carver, a trait which appeared in his great- nephew, VI, 3. IV, 17, married, and two children were proficient in the N. Y. Academy of Design. IV, 7, had an artistic turn of mind and her daugh- 54 HEREDITY IN RELATION TO EUGENICS children will have high artistic talent. But if the unartistic parent have artistic ancestry there will be artistic children. From 15 such matings there were derived 37 children of whom 15 were poor in artistic ability and 22 medium. Among the 120 children derived from the mating: non-artistic parent having some artistic ancestors X artistic parent, there were 43 with exceptional artistic ability. 9. Asitiry IN LireRARY COMPOSITION The inheritance of the ability to express oneself in literary form is commonly recognized. ‘‘ Poets are born; not made.” Many literary men show their talent very early, before they had received much training in expression. Burns, the plow- boy, was celebrated as a poet at 16, Calderon at 14, Goldoni produced comedy at 8, Charlotte Bronté published ‘‘Jane Eyre” at 22, Fénélon was known at 15, Sir Philip Sidney was famous at 21. As illustrations of heredity we have two of Charlotte Bronté’s sisters writing a famous book, besides a brother Patrick said to be the greatest genius of them all. The father and the father’s father of T. B. Ma- caulay, two uncles, a cousin and a nephew were all writers of note. Four generations of Taylors in England were authors of an ‘‘evangelist disposition.” The precise method of inheritance of literary ability has not hitherto been made clear; but a study of the Family Records seems to justify the following conclusions. When both parents have high to good literary ability all (or nearly all) of the children will have likewise good literary ability. There are 643 offspring of such matings in the Family Records and of them 93 per cent have medium to high literary capacity. No doubt these terms are used somewhat loosely and this may account for the exceptional cases. ter, Mary L. B., had a decided artistic talent which she inherited from her father’s family as well as her mother’s. It may be of interest to state further that VI, 3, possessed a mechanical genius, as did his great-grandfather, Joseph B., III, 6, a skilled jeweler, many of whose descendants to the fourth generation were also skillful jewelers. THE INHERITANCE OF FAMILY TRAITS 55 When both parents have poor literary ability and come from a strain devoid of it the children will, typically, have poor literary capacity. This generalization is based on the 19 children, all non-literary, of four matings of this sort. But when literary ability appears in remoter ancestry ‘it will occur in some of the children. Thus in 23 matings of this sort only 25 per cent of the children are without literary capacity. ‘ 10. MrcHANIcAL SKILL There can be little doubt of the inheritance of some of the elements of mechanical ability. The case of John Roebling and his sons, builders of the first. great suspension bridge over the East River, New York City, and of Charles Martin, long chief engineer of that bridge, and his son, Kingsley Martin, for some years chief engineer of the bridges of New York City, are examples familiar to modern Amer- icans. Not less striking is the family of boat designers whose pedigree is shown in Fig. 24. Five of the seven sons of the illustrious head of the family were inventors and boat designers, and high technical ability has appeared also in the third generation. The Pomeroys are another American family that illus- trates the inheritance of mechanical skill. The first of the family in America was Eltweed Pomeroy at Dorchester in 1630 and later at Windsor, Connecticut. He was by trade a blacksmith, which in those days comprehended prac- tically all mechanical trades. His sons and grandsons, with few exceptions, followed this trade. ‘‘In the settle- ment of new towns in Massachusetts and Connecticut the Pomeroys were welcome artisans. Large grants of land were awarded to them to induce them to settle and carry on their business.” ‘‘The peculiar faculty of the Pomeroys is not the result of training and hardly of perceptible volun- 56 HEREDITY IN RELATION TO EUGENICS 1 SobbEs m on ae rbd : f ta Fic. 24.—Pedigree of family with mechanical and inventive ability, par- ticularly in respect to boat-building. I, 2, a suicide: II, 1, a suicide. His brother, II, 5, a builder of swift boats and yachts, II, 7, insane; II, 8, eccentric. The union of these two strains with evidence of nervous instability resulted in a family of 9 children and 18 grandchildren. Four of the sons show a high degree of inventive ability and 2 of these III, 8-12, developed the genius of their father in designing and building swift and beautiful boats. Three ‘are musicians, III, 10, 11, 17, and one of them, III, 11, shows also mechanical ability. In the next generation these traits reappear in the various frater- nities. IV, 1, is a musician; 2 has much mechanical skill and 3 is inventive; 5, is a builder of fine boats; IV, 11-15 represent 5 boys, none over 22, but already designing boats; two other daughters of this generation show artistic and musicial talent and, finally, in the next generation we have a girl of 14, V, 3, designing boats. F. R.; H tary effort in the individual. Their powers are due to an inherited capacity from ancestry more or less remote, devel- oped for generations under some unconscious cerebration.”’ There was Seth Pomeroy (1706-1777) an ingenious and skill- ful mechanic who followed the trade of gunsmith. At the capture of Louisburg in 1745 he was a major and had charge of more than twenty smiths who were engaged in drilling captured cannon. Other members of the family manu- factured guns which in the French and Indian wars were in great demand and in the Revolution, also, the Pomeroy guns were indispensable. ‘‘Long before the United States had a national armory, the private armories of the Pomeroys were famous. There was Lemuel Pomeroy, the pioneer manufacturer of Pittsburg, stubborn but clear headed, of whom a friend said: There would at times be no living THE INHERITANCE OF FAMILY TRAITS 57 with him if he were not always right.’”’ There was also Elisha M. Pomeroy of Wallingford a tinner by trade. He invented the razor strop and profited much by its success. [C. H. 8. Davis, 1870, History of Wallingford.] In the sixth generation we find Benjamin Pomeroy a successful lawyer entrusted with important public offices. ‘But he was conscious of powers for which his law practice gave him no scope. He had a taste for mechanical execution, and as a pastime between his professional duties under- took the construction of difficult public works—the more difficult the better he liked them. The chief of the United States Topographical Engineers was a friend of Mr. Pom- eroy and repeatedly consulted him in emergencies wherein his extraordinary capacity was made useful to the govern- ment. By him were constructed on the Atlantic coast beacons and various structures in circumstances that had baffled previous attempts.’ The value to this country of the mechanical trait in this one germ plasm can hardly be estimated. Especially is it to be noted that, despite con- stant out-marriages, it goes its course unreduced and un- modified through the generations. The Fairbanks family of St. Johnsbury, Vermont, illus- trates the inheritance of inventiveness combined with execu- tive ability, specialized in the iron trade. The inventor of the ‘platform scales” belonged to a family not merely of iron workers but to one with imagination such as made other members literary men (Fig. 25). The Family Records give rather definite information as to the method of inheritance of mechanical skill. When both parents have good or exceptional mechanical skill all of their children will have it also. Out of 413 children of such matings (including both sexes) all but 7 show some mechanical ability, and 118 of them ability of an exceptional order. Indeed, most persons of exceptional skill come from this mating. 58 HEREDITY IN RELATION TO EUGENICS I WV Fic. 25.—Pedigree illustrating inheritance of special ability in the Fair- banks family of Vermont. I, James Fairbanks; I, 2, Phoebe Paddock. Her two brothers, I, 3 and 4, were iron workers, II, 1, Erastus Fairbanks moved at 19 years to St. Johnsbury, Vermont and began to manufacture stoves, plows, etc.; II, 2, Lois Crossman; II, 3, Thaddeus, a natural mechanic, invented the platform scales; II, 4, Lucy Barker; I], 5, the third brother, Joseph P. Fair- banks was a lawyer, with literary tastes. Erastus and Lois had two sons of whom the elder, III, 1, went into the scale business, showed much inventive ability and a strong taste for natural history. His brother Horace, III, 3, was an excellent administrator and became Governor of Vermont. Dr. Henry Fairbanks, III, 6, son of Thaddeus went into the ministry, but his love of invention drew him into the iron business. He combined mechanical and literary gifts. III, 8, was a minister and III, 9, a sagacious and exact man, was secretary and treasurer of the Fairbanks Com- pany. If both parents lack mechanical skill and come from an ancestry that lacks it no offspring will have mechanical ability. Even if mechanical skill is found in the ancestry of one side, but not of the other, still there will be no marked mechanical ability in the children. ~ If one parent has mechanical ability and the other belongs to a strain that lacks it then exceptional mechanical ability will be absent or uncommon. But if the parent that lacks mechanical ability comes from an ancestry that pos- sessed it a large proportion of the children will have such ability. Also when both parents that have slight mechanical ability are descended, on one side, from persons with skill, such skill will reappear in approximately one child in four. THE INHERITANCE OF FAMILY TRAITS 59 11. Catcunating ABILITY The inheritance of great mathematical ability cannot be denied and is well illustrated in the case of Bernoulli: Jac- ques, his nephews Nicholas and Jean, and three nephew’s sons were mathematicians of high rank. Our Family Records afford a limited amount of data on the subject of inheritance of mathematical ability. They do give information concerning the inheritableness of the ability to calculate—a broader phenomenon. The follow- ing rule seems justified: When both parents are good at calculating all (or nearly all) of their children will be so likewise. Of 728 offspring of this class of matings all but 48 (or 8 per cent) were good at calculating. In no case were both parents returned as poor at calculating; but in 47 matings both parents were only medium and 13 per cent of their children were poor at calculating. 12. Memory There is no doubt that people vary in their ability to remember and there is no question that a good memory is an innate quality. Phenomenal memories are often asso- ciated with mental defect in which case it is clear they are independent of training. In other cases they are associated with high scholarship. Thus Galton cites the case of Rich- ard Porson, an eminent Greek scholar, whose memory became stupendous. His mother had a remarkable memory and so did his sister. The Family Records throw some light on the inheritance of a good memory; although the term is a relative one and lacks in precision. Nevertheless for a preliminary study the data are not to be despised although there are not a few exceptions to any generalizations one may hazard. When both parents have an exceptionally good memory 60 HEREDITY IN RELATION TO EUGENICS most, if not all, of the children have a memory that is medium to exceptional.+ When both parents have a poor memory and come from ancestry so characterized few if any of the children have an excellent memory. Two “poor” parents (with “poor” grandparents) have 10 children all with poor memory. When one parent has a memory that is either excellent or fair and the other has one that is “poor” all children have a medium memory; and, conversely, parents with medium memory may have 20 to 25 per cent of children with excellent and as many with poor memory. 13. CoMBINED TALENTS AND SUMMARY OF SPECIAL ABILITIES While the separate talents may, for purposes of analysis, be considered separately they usually, as our illustrations suggest, occur in combination in a single family. And such talents are frequently enough associated with insanity or mental defect in some of its members as apparently to justify the poet’s conclusion: ‘‘Great wits are sure to mad- ness near allied” (Fig. 26). In many cases artistic, literary and musical talent are found in the same family—two or all three of them are occasionally found in the same person (Fig. 27, Fig. 28). The conclusion seems justified that artistic, literary and musical skill are unit characters that may occur in any combinations—the common inherited factor may be only a highly developed imagination. In the foregoing cases the method of inheritance of many of the elements of the mental makeup have been considered 1 The Family Records give 4 per cent of children of such matings as having a poor memory. THE INHERITANCE OF FAMILY TRAITS 61 and the remarkable result has been deduced that the higher grades of all these qualities act, in inheritance, as though they were due to the absence of something that is present ‘merch, | 138 rn rosea mental court Judge T'S gat Okeroa Ft inveltect Weak. fineintel. musician neurotic able ty8 restive brain dissolute painter Keenwit engineer ‘sailor tumor Fic. 26.—Pedigree of brilliancy combined with defect and melancholia. F.R. in persons of poorer ability. It is as if the difference between a person of high ability and one of low ability in respect to any mental trait is that the person of high ability has so 0 ESbSS HEL SSASOS rere Fic. 27.—Pedigree of family with artistic (dark upper section), literary (right section) and musical (left section) ability. got rid of a something possessed by the person of lower ability that prevents the latter from fully exercising his faculties;—he has sloughed off one or more inhibitors. 14. TEMPERAMENT Two contrasted temperaments are usually recognized. e One phlegmatic, slow, rarely depressed; the opppsite ner- 62 HEREDITY IN RELATION TO EUGENICS 0 ‘BO BAG vate) Tekh er ee se sia i tb. Fic. 28.—Pedigree of a pedigree-complex (Abbott-Buck-Wolff) showing inheritance of musical (dots), literary (horizontal lines) and inventive (vertical lines) ability. Variations in the area covered by each symbol indicate roughly a variation in degree of ability of the given kind. I, 1, a musician of the eighteenth century and I, 2, his wife, the daughter of a professor of music. One of his sons adopted a seafaring life and died in Mozambique. Two sons, II, 8, 11, were instructors in the Geneva Conservatory of Music. The son, III, 21, of one of these was a professor of music and a composer. The other married a woman, II, 7, with literary and musical ability and had four chil- dren of whom III, 19, was a literary composer; III, 18, had good musical ability; III, 20, was brilliant piano player with a fine baritone voice and literary; and III, 17, both literary and musical, married a man with inventive ability whose first cousin, III, 9, was an organist and musical composer of high rank. Two of their children, IV, 14, 15, show literary ability and IV, 14, inventive ability also. He married into a family famous in American literature and with much musical ability and the product was two children both literary and one, V, 7, an inventor of high rank. III, 1 and 3, derived from a musical father, have literary ability of a high order. One who has also some musical ability married a very musical wife and of the 4 sons at least 3 have musical ability. One of these, IV, 3, combined with the musical also literary ability, married a woman with some literary ability and had 4 sons of whom 3 at least are littera- teurs and two have much musical ability. V, 5, is a well-known authoress. vous, quick, often elated or alternately elated and depressed. Between the extremes lie, as is usually the case, many intermediates. While it is clear that there are no sharp lines to be drawn between these conditions, some insight into their hereditary behavior may be gained by an exami- nation of the opinions furnished by collaborators in the Family Records. When phlegmatic is assumed to be a condition recessive to the “inter- mediate” and nervous conditions we find that in three families with 13 offspring, 10 or 77 per cent, are likewise phlegmatic. On the other hand, when nervous is assumed to be recessive to intermediate and phlegmatic in 130 offspring of nervous parents 64 or 49 per cent were nervous, THE INHERITANCE OF FAMILY TRAITS 63 So far as the data go they support the following conclu- sions. The offspring of two phlegmatic parents tend to be phlegmatic and the nervous parents of purely nervous origin have nervous children. But one phlegmatic parent mated to a nervous one will produce chiefly nervous chil- dren and many who are intermediate. When both parents are nervous with phlegmatic ancestry a fairly large pro- portion (up to about a quarter?) will be phlegmatic. 15. HaNDWRITING Inheritance of peculiarities of handwriting is often al- leged (Darwin, 1894, p. 449), but it is difficult to get satisfactory evidence about it. A correspondent (Hal-2) writes:—‘‘We belong to a family of penmen. My four brothers and myself inherited our handwriting (the Eng- lish legal copyist’s handwriting) from my father. Two of our uncles and two cousins also wrote the family hand. I believe it was asserted that our paternal grandfather wrote the same. We could distinguish the writing of each, but the general family resemblance was there, especially when we were all young men and my father was not old... . We descended from a family that included officemen, lawyers, recorders to whom expert penmanship was nec- essary.” 16. GENERAL Bopity ENERGY Of the inheritance of this quality there can be no doubt. If we take the class of commanders as one characterized above all by bodily energy we see the intensity of its hered- ity. It is exemplified in the family of Alexander the Great from Philip of Macedon down, the family of Charlemagne including Pepin le Gros and Charles Martel, of Gustavus Adolphus, and of Scipio Africanus. 64 HEREDITY IN RELATION TO EUGENICS Can we discover how bodily energy, which reaches its highest degree in such commanders, is inherited? Here again I appeal to the Family Records in which energy is recorded in the three grades: below average, medium, de- cidedly above average. The following principles seem estab- lished. When both parents have bodily energy that is regarded as ‘decidedly above average”’ all of their children will have either exceptional or at least medium energy. The mating of two energetic parents in 192 families produced 413 off- spring (or 2.2 children to the family). Of these 301 (73 per cent) are placed in the highest grade; 100 (24 per cent) in the middle grade and only 12 (3 per cent) in the low grade. Considering the probability of errors this lowest grade is negligible. When both parents have medium to low energy and come from ancestry of this sort all offspring have medium to low energy. \ There are 54 matings of this sort, with 219 children (or 4.1 children to the fraternity): All but 4 are in the medium class. When one parent has great bodily energy while the other has no great energy in himself or his ancestry all-of the children (86) have medium (82) or low energy (4). But if there be energy in the grandparents on the low side about half of the children will have energy that is decidedly above the average. There are 105 matings of the latter sort, producing 456 children (or 4.3 children to the fraternity) of whom 226 were classed as of great energy, 208 of medium and only 22 as low. On the whole the facts support the hypothesis that ex- cessive bodily energy is due to a loss of something—perhaps an inhibitor that prevents persons from achieving the best that is in them. However, the whole subject deserves a more thorough investigation. THE INHERITANCE OF FAMILY TRAITS 65 17. Genera Bopity STRENGTH Like other bodily traits general strength is clearly in- herited. This appears repeatedly in our records. An ex- ample is given in Fig. 29. O Fic. 29.—Inheritance of muscular strength. I, 1, of great physical strength. His son II, 3, was likewise possessed of unusual strength. His elder son in turn was athletic but became dissipated. F. R.; St. 1. 18. GENERAL MENTAL ABILITY The general mental ability of a person is a vague concept - which is, however, in common use. We speak of a man as weak minded, as of mediocre ability, as exceptionally able without attempting a closer analysis of the subject. General mental ability, like stature and weight, under- goes a progressive development so that in studying its heredity we must compare it in adult persons or else measure it by the deviation the person shows from the normal of his age. Thus we may call ‘“‘weak mindedness”’ such a defect as would keep a child of 10 in a school grade where the other children are 6 or 7; a child of ‘‘mediocre” ability is not * more than two years behind the average grade for his age; “exceptionally able” would imply, say, two years in advance of children of his age. A series of tests (the Binet-Simon tests) have been devised to gauge mental ability by gauging a variety of capacities such as general information, ability to count and to repeat phrases, to recognize names and describe common things and to make fine sense discrimina- 66 HEREDITY IN RELATION TO EUGENICS tions. Such tests show that there are all grades of mental ability. At one extreme is the idiot, without language and incapable of attending to his bodily needs. He may retain to maturity the mentality of a child of afew months. Ina higher grade mentality of a child of 3 to 5 years is retained throughout life; such are the imbeciles; then come the merely backward children who make dull adults of all Fic. 30.—Family group from a long-settled valley where much consan- guineous marriage has taken place. grades to the normal condition (Fig. 30). Finally, there are the exceptionally bright, quick children some of whom at least, become superior adults. It is hard to recognize a unit character in such a series any more than in human hair color. Nevertheless there are laws of inheritance of general mental ability that can be sharply expressed. Low men- tality is due to the absence of some factor, and if this factor that determines normal development is lacking in both parents it will be lacking in all of their offspring. “Two mentally defective parents will produce only mentally defective offspring. This is the first law of inheritance of THE IN HERITANCE OF FAMILY TRAITS 67 mental ability. It has now been demonstrated by the study of scores of families at the Vineland (N. J.) Training School for defectives by Dr. H. H. Goddard. Some pedigrees il- lustrating this law, and those that follow, are given in Figs. 31-35. EH-O OO Om OHOSmH HERES & Fic. 31.—Pedigree chart illustrating the law that two defective parents have only defective children. A, Alcoholic; C, criminalistic; D, inf., died in infancy; F, feeble-minded; N, normal, 7, tubercular. Gopparp, 1910. The second law of heredity of mentality is that, aside from ‘‘mongolians,”’ probably no imbecile is born except of parents who, if not mentally defective themselves, both carry mental defect in their germ plasm. Fig. 36 (left side of chart). Many a person of strong mentality may carry defective germ cells and, whenever two such persons marry, expectation is that one-fourth of their offspring will be defective. If a person that belongs to a strain in which defect is present (and who, consequently, may be carrying the defect in his germ plasm) marry a cousin or other near relative (in whom the chance is large that the same defective germ plasm is carried) the opportunity for two defective germ cells to unite is enhanced. Such consanguineous mar- riages are fraught with grave danger. In view of the certainty that all of the children of two feeble-minded parents will be defective how great is the folly, yes, the crime, of letting two such persons marry. It 68 HEREDITY IN RELATION TO EUGENICS EH-® OHOOLO, HHOHHHOOHHE 7 VRS. Oo Ff, ©OHOOL,@OHO® 2nd WIFE DW@@OEHO TWING Fic. 32.—Pedigree chart illustrating the inheritance of feeble-mindedness. In chart A, the central mating is of an alcoholic man with a normal woman who died of tuberculosis. Of their 11 children, 5 are known to be ngrmal, the others died early. Then (B) this man married a feeble-minded woman and of 7 children 3 are certainly feeble-minded, and 2 were, as young children, killed at play, in a fashion indicating a lack of ability to avoid ordinary dangers. Gopparp, 1910. =) N--@_ti G-® ©HANNN @6GH6n N@OOe ma! ! Gam@:!: mos: wos. Fie. 33.—Here a feeble-minded woman (of the first generation). has married a normal man and has 4 normal children (except that 1 is alcoholic); then she marries an alcoholic sex-offender (who is probably also feeble-minded) and has 4 feeble-minded children. Here the mental strength of the first husband brought the required strength into the combination, so as to give good children. Gopparp, 1910. THE INHERITANCE OF FAMILY TRAITS 69 60 6°68 o daa ao Fic. 34.—An alcoholic man of good family but probably simplex in men- tality has by a normal woman 2 normal children and by a feeble-minded woman 2 normals and 1 feeble-minded. He has had 4 other children by feeble-minded women, all feeble-minded. Sz, sex-offender. Gopparp, 1910, o-O -O O,fOf oO NN Ist WIFE aad ada a4 INF. INF. INF, UNF. INF, INF. 2nd HUSBAND. 9H6H66! On 6: Fig. 35.—This chart shows several cases of entirely feeble-minded progeny from two defective parents. Gopparp, 1910. has happened many times that keepers of poorhouses have let feeble-minded women in their charge go to marry a half- witted farmer in order to relieve the town of the burden of maintaining her. Some years later both she and her hus- band come to the poorhouse as permanent inhabitants and 70 HEREDITY IN RELATION TO EUGENICS EH-© a) HOOHHHHOOE OOOH | ‘HE OOBH Fic. 36.—Pedigree of a “mongolian” imbecile. Except for an insane uncle (1) there is no evidence of a psychopathic condition in the parental germ plasms. Gopparp, 1910. bring half a dozen imbecile children to be a permanent charge on the community. Surely there is no economy in this. A still more appalling piece of testimony is given by a delegate from Alabama to the 26th National Conference of Charities and Correction. He said: ‘‘In our poor institu- tions the males and the females are allowed to run together and, so long as that is allowed, you cannot cut off the in- crease. It is perfectly appalling how the children accumu- late in institutions.” Anyone acquainted with rural poorhouses (Fig. 37), particularly in the South, will appreciate that the people housed in them are mostly mentally inferior. By bringing together defective men and women, without proper segrega- tion of the sexes, and by protecting and nursing the defective offspring of defective parents and then turning them out upon the community, the improperly conducted county poorhouses constitute one of the country’s worst dangers. What is the state of your county poorhouse, reader? An apparent paradox may well have occurred to the reader, and that is that mental defect and the elements of exceptional ability are inherited in the same way. This certainly looks like a self-contradiction. Are not the feeble- THE INHERITANCE OF FAMILY TRAITS 71 B-1824 p60 1 2.4 §& 6 Fisx. — ree Sirive eases et ace oO se ise ie= er 4 eo + ee eee a ae fem el os : ' ‘Negro ' : ' Bo 4 : ' ' ' i © Alms House wre ee E oldiers Home-Kearney =D =O B-lgg9 31842 —O Fig. 37.—The ‘“‘poorhouse” type of reproduction of the feeble-minded and epileptic. A lewd, feeble-minded and epileptic woman whose mother was certainly feeble-minded (but of whose father, brothers and sisters noth- ing is known) was the inmate of a county poorhouse. While there she had 6 children, of whom 2 died in infancy, 1 died at 18 in the almshouse, 2 were feeble-minded and are now living in the almshouse (1 the son of a negro) and 1 was epileptic, the son of a man with a criminal record. C, criminalistic; D, dead; E, epileptic; F, feeble-minded; S, syphilitic; Sz, sexu- ally immoral. . minded and the talented at opposite extremes of the mental series? Why, then, this resemblance in the inheritance of their traits? Improbable as the result may appear it is precisely that to which students of hereditary genius have come. Says Havelock Ellis: ‘‘We may regard it (genius) as a highly sensitive and complexly developed adjustment of the nervous system along special lines, with concomitant tendency to defect along other lines. Its elaborate organiza- tion along special lines is often built up on a basis even less highly organized than that of the ordinary average man. It is no paradox to say that the real affinity of genius is with congenital imbecility rather than insanity.’ Ellis notes that eminent men are more apt to be eldest or youngest sons. Now this fact is in agreement with the observation that feeble-minded persons of certain types (‘‘mongolians, ”’) are more apt to be eldest or youngest children than inter- mediates. This type seems to be caused solely by the defects ~ 72 HEREDITY IN RELATION TO EUGENICS in development due to imperfect nutrition of the child born of parents (particularly mothers) that are immature or too old. The contention that geniuses and some defectives are born chiefly at the extremes of the reproductive period sup- ports the view of their relationship. 19. EprItersy This term is believed by many professional men to cover a number of distinct brain disorders that have in common the symptoms known as convulsions or ‘‘fits.” All too little is known about the physiology of the forced move- ments of convulsions, accompanied as they typically are by temporary loss of consciousness. It is known that convul- sions may sometimes be induced in guinea pigs by a heavy blow on the brain case, and similar injuries are stated to have produced epilepsy in man. In other cases the ‘‘ cause” is stated to be disturbance in the cerebral circulation due to a local stoppage in the blood vessels. However, it may well be questioned whether such causes are sufficient and not merely inciting, whether an inherent weakness did not first exist, which was only disclosed by the blow or disturbance in the circulation. A fall on the ice may result in a child’s first epileptic fit but thousands fall on the ice without more than temporary discomfort; it was not the fall merely but the fall plus the too delicate nervous organization. The hereditary basis of epilepsy has been studied and, rather remarkably, it follows the same laws as feeble- mindedness. Two epileptic parents probably produce only defective offspring, and the defect sometimes takes the form of epilepsy, sometimes that of feeble-mindedness. It does not seem necessary to repeat the laws of heredity for epilepsy since in them the words epilepsy and feeble- mindedness are almost interchangeable (Figs. 38-43). The warning against the evils of poorhouses as breeding THE INHERITANCE OF FAMILY TRAITS 73 -O GL Brights See Chart Disease 2013 4 @TheN.J State Home for Boys - Poor Farm - New Brunswick er oa Childrens Industrial Home - Brights Ws New Brunswick- Disease Fig. 38.—The product of a feeble-minded man (who has an epileptic brother) and his epileptic wife (whose father was insane and uncle feeble- minded); the first child died in infancy, the next two were feeble-minded and died young, the next is an epileptic at the New Jersey State Village; the next is feeble-minded, has a criminal record and is in the State Home for Boys; the last is feeble-minded and is in the Children’s Industrial Home. Six in this family have been or are wards of the State. A, alcoholic; C, criminalistic; D, deaf; E, epileptic; F, feeble-minded; J, insane; N, normal. SV in the [> means an inmate of a State Village for Epileptics. 1 ET Boe wal, D D B-16s2 O (To Na] QOsHCNHOSE AAW AA 1 DI Onaaa Be 3 a Yo fom Of 1 SO ToT? ‘Te S 6 EOS cr) B-1892 64889 B1898 coca adeéu Dl DS DS BMG B189S §=—_-B-1899._-B-1901 B-1902 & Twins ‘ Fia. 39.—The central mating is that of a feeble-minded woman of an in- tensely neuropathic strain and an alcoholic man, who has 3 alcoholic brothers, father and grandfather alcoholic, an insane cousin and an epileptic nephew. The husband, though recorded as alcoholic, is probably also feeble-minded, at least all (6) of his children who survived were feeble-minded or epileptic. This chart shows 4 wards of the State and many others who should have been segregated. A, alcoholic; B, blind; B, (below), born; D, deaf; D, (be- low), died; E, epileptic; F, feeble-minded; Ht, heart-disease; J, insane; Par, paralysis, Sx, sex-offense; 7’, tubercular. 74 HEREDITY IN RELATION TO EUGENICS places of feeble-mindedness needs to be repeated for epilepsy and the dangers of consanguineous marriage are equally great (Fig. 43). If these two sources of epileptics—namely the poorhouse and the hovel (Fig. 44)—were cut off the supply of epileptics would be markedly reduced. And it is Fig. 40.—This mating illustrates the principle that migraine (M) and paralysis frequently indicate the presence of defective germ cells, as well as normal. In the central mating the paralytic father has an insane brother, an insane niece and 3 feeble-minded grandnephews, besides a grandniece, who died in convulsions. By his migrainous wife he had 12 children about 9 of whom something is known. One is epileptic, 3 ‘“‘neurotic” or very nervous, 1 “peculiar” and alcoholic, while 3 are normal. The epileptic child has by an alcoholic husband 2 epileptic sons. Abbreviations as in Figs. 38, 39. to be observed that these two sources of supply are quite within the control of society. A little larger appropriation to provide for the complete segregation of the sexes and a better superintendence will shut off the poorhouse supply and the inmates of the hovels should be brought under surveillance,—if necessary under public care. THE INHERITANCE OF FAMILY TRAITS 75 O D B1B75 Qe OOOOW 2nd Husband DT B-1900 B-1904 leurotic St Vitus Dance B-189G6 ~—_—B-1899_ B-1904 Fic. 41.—The central mating in this chart is that of an epileptic man, of a highly neuropathic strain, and a neurotic woman, whose sister and nephew have had chorea or St. Vitus’ dance. The product is 1 normal child, 1 epileptic, and 1 as yet only 7 years old. Abbreviations as in Figs. 38, 39. _D Malaria B-1886 §=B-18G9 B-1888 = B-189] B-189G —_B-1898 B-1901 g Fig. 42.—The central mating is that of 2 normal parents, both of whom belong to stock that shows evidence of being neuropathic. Doubtless some of the germ cells of both parents are defective in mental strength. Along with 6 normal children appears 1 epileptic. Abbreviations as in Figs. 38, 39. Figs. 37-48, are contributed by Dr. Davin F. WEEks. 76 HEREDITY IN RELATION TO EUGENICS min +] [bp ® County Jail-MonmouthCo. @Alms HouseMonmouth Co, Fic. 43.—The ‘“Hovel”’ type of reproductions of defectives. In a hut in the woods there was brought up a family of defectives. “One of the boys, who is a drunken, feeble-minded fellow with criminalistic tendencies, had by his own sister a daughter who is a drunken epileptic, who has beer the inmate both of the county jail and the county poorhouse. By her father she had 4 children of whom 1 is epileptic, 2 are feeble-minded (the girl has a very bad record of drunkenness, crime and immorality) and the other one was an idiot monster who died directly after being born. Close inbreeding of such a strain results only in this imperfect fruit. Abbreviations as above. Fig. 44.—A hovel in a rural district, removed from social influences and liable to become the scene of anti-social acts. F. W.; 5, 1911. THE INHERITANCE OF FAMILY TRAITS 77 20. INSANITY If the word epilepsy is a wardrobe then the word insanity is a veritable lumber room, including a great variety of mental diseases which have this in common that they render their victim incompetent and irresponsible before the law. Two great classes of insanity are distinguished: the “‘or- ganic” and the “functional.” The first group includes cases of mental deterioration associated with venereal dis- eases, alcoholism, degeneration of the blood vessels and trauma; the second includes cases of distinct neuropathic taint which shows itself in the slighter forms as melancholia or manic depressive insanity and in the profounder forms as dementia precox. Concerning heredity in the functional forms there is no doubt. Berze (1910) gives a case of de- mentia precox in a father and three sons; another of two children, their mother and her father; and numerous other cases with two or three to the family—all with a more or less typical form of dementia precox. But the mental de- fect that is ‘inherited’ is not always of the same type. Thus in the same family may be found cases of manic de- pressive insanity, of senile dementia, of alcoholism and of feeble-mindedness. It would seem to be the neuropathic taint that is inherited. This is the conclusion to which Cannon and Rosanoff (1911) have come in their study based on house to house investigations of the families of patients at a State Hospital. They omit from consideration the “organic” class of cases as ‘‘probably purely exogenous in origin.”’ Aside from these they find that when both parents have any form of insanity all of their children will ‘‘go insane.”’ If one parent is in- sane and the other normal but of insane stock half of the children tend to become insane; when both parents, though normal, belong to an insane stock about one-fourth of the 78 HEREDITY IN RELATION TO EUGENICS I MO ne 1 SELSSEESESSOD I Fig. 45.—The central mating, II, 7, II, 8, is that of a man, II, 7, who is subject to melancholia and has an insane brother and another who is neuro- pathic. His wife is normal but her mother was neuropathic. The product of this union is 11 children of whom 3 are neuropathic. One of these insane children marries a normal person (probably of neuropathic ancestry), and has 2 neuropathic children besides 1 that is epileptic, IV, 1. 4, epileptic; I, insane; N, normal; shaded symbols imply some neuropathic condition other than insanity. Cannon and Rosanorr, 1911. INV) FebboSbOaddaaeddod Shbbhoad Fie. 46.—The central mating is that of a normal man of neuropathic stock with a neuropathic woman who has an insane sister. Since by hypothesis all of her germ cells and half of his are “neuropathic” it is to be expected that half of their offspring will be neuropathic in some degree. Actually, of 6 sur- viving children 2 are epileptic, 2 highly nervous and 2 normal so far as known. There is a slight, but not unreasonable deficiency of normals, namely, 1. The shaded symbols represent nervous subjects. CANNON and Rosanorr, 1911. children become insane. The typical laws of heredity are followed here (Figs. 45-47). But is it so certain that alcoholic, traumatic, even syphil- itic dementia have no hereditary basis? On the contrary THE INHERITANCE OF FAMILY TRAITS 79 salud 60 oenené Fic. 47.—The central mating is that of a pair who, though not insane, have pronounced neuropathic manifestations. The mother has an insane sister and the father comes of neuropathic stock. Of the 3 surviving children 1 is neurotic, 1 insane and 1 epileptic. A similar mating of 2 neuropathic persons is seen in the parents of the father—all of their off- spring are neuropathic. The shaded symbols represent neuropathic in- dividuals. Cannon and Rosanorr, 1911. Om choedsoaa SESE bbogs digg tinf tinf qo ame oor tinf Fig. 47a.—Inheritance of ‘insanity.’ From the central mating of 2 normal persons there are derived 8 children, 3 insane. But there is the heredi- tary tendency in the germ plasm of both parents. Mort, 1905. it is fairly open to debate whether alcoholics are not usually mentally defective and the delirium tremens that develops is a symptom of their mental weakness. Similarly a blow is often just the stress that reveals the mental weakness; 80 HEREDITY IN RELATION TO EUGENICS the syphilitic poison in some, if not most cases, likewise acts most disastrously on the neuropathic constitution. Thus, probably an hereditary predisposition lies at the basis of most cases of insanity; and this predisposition behaves in heredity like a defect. 21. PAUPERISM Pauperism is a result of a complex of causes. On one side it is mainly environmental in origin as, for instance, in the case when a sudden accident, like death of the father, leaves a widow and family of children without means of livelihood, or a prolonged disease of the wage earner exhausts savings. But it is easy to see that in these cases heredity also plays a part; for the effective worker will be able to save enough money to care for his family in case of accident; and the man of strong stock will not suffer from prolonged disease. Bar- ring a few highly exceptional conditions poverty means rela- tive inefficiency and this in turn usually means mental inferi- ority. This is the conclusion that social workers in many places have reached. Thus from Harrisburg, Pa., come these cases: (a) Mr. and Mrs. R., applicants for relief and living in a slum district, are parents of 14 children of whom 10 are living. These parents are both epileptic and feeble-minded. (b) Mother and father are both feeble-minded. There are 6 children, all of marriageable age, all unfit to earn in any case more than $1.50 per week, and all recipients of public alms. Such cases might be multiplied indefinitely. In the larger pedigrees of the Jukes and Zero families more definite data as to inheritance of some of the elements of poverty can be gained. Let us take “‘shiftlessness” as an important element in poverty. Then classifying all persons in these two families as very shiftless, somewhat shiftless, and industrious the following conclusions are reached. When THE INHERITANCE OF FAMILY TRAITS 81 ‘IT MeyO ‘2061 ‘A1IVapaq ‘oNsi~eurmuo ‘gt TIL SALT {0preq ‘Z ‘AT ‘Aqsodord ovmos pasmboe 1048] oy Jodned pus sJoyxeuU-joyxseq ‘QZ ‘TIT pie one pue sadned ‘9% ‘TIT ‘edned ‘opeq ‘FZ ‘TIT ‘snonueoy “Gz “TIT ‘301ey ‘OZ “TIT -Jedned ‘snornusoy “6 ‘TIT -A0q ped ‘ST “TIT ‘yomex Io ‘ZT ‘TIT ‘Joyor yno qref “yopreq ‘TT ‘TIT ‘eyeurur esnoysood “yoyrey ‘OT ‘TIT ‘tedned ‘sorpjos “6 ‘TTT ‘Jouor yno 97441] @ Peapoo. "9 III ‘yet ur gueisea ‘, ‘TIT ‘yeyer yno peateoor “9 ‘g “TIT Sumouy opy “€ %Z “T “TIT ‘umouyun ‘9g ‘TT ‘sanoK porp “6r ‘IT ‘s0[784 @ ‘QT ‘TT {snomusoy ‘Azey ‘ZT “TT ‘Joyar yno op47] B Jo yuoldroor yorrey B ‘FT ‘TI ‘esnoysood ur la OL ‘II scans L JI ‘yet ‘Jeyor gno “Queaisea ‘g ‘[] [Aoweisea 4messe ‘ssoulzey ‘¢ ‘TT ‘Jorer yno Jo quardioor oo1m4 ‘| ‘TT pia Bs pay Azey ‘Z ‘TI ay pio Joy jel ut ‘Jaljar Joop yno jo quardroer yuonbeay v ‘T ‘TT ‘oyeredu1e7 ynq “Jo;Tey snoLysnpul-uou Be ‘Z ‘T /o4}e_NUT Aaey eT Y he ‘(sgoqurAs poyelrys) ssoussel}jrys [erred pue (sjoquids youTq) ssaussayfrys JO ooUCL -m900 Zutmoyg $=, Seyne epy,, JO 1ayqZnep Jepja ey} jo syuvpusosep Zutog ‘oorsiped syne oy} jo JUSUIBVIy Y—'gp ‘DIY i ae al cd 82 HEREDITY IN RELATION TO EUGENICS both parents are very shiftless practically all children are “‘very shiftless” or ‘“‘somewhat shiftless.”” Out of 62 off- spring, 3 are given as ‘‘industrious”’ or about 5 per cent (Fig. 48). When both parents are shiftless in some degree about 15 per cent of the known offspring are recorded as industrious. When one parent is more or less shiftless while the other is industrious only about 10 per cent of the children are ‘‘very shiftless.” It is probable that both shiftlessness and lack of physical energy are due to the absence of something which can be got back into the offspring only by mating with in- dustry. 22. NARCOTISM The love of alcoholic drink, opium, etc., is commonly re- garded as due solely toits use. It has even been asserted that the ‘‘taste” is usually an acquired one; and we are assured that drunkenness results from bad associates and imitation of bad habits. Cases are cited of persons who, after an exem- plary youth, have suddenly through drink been started on the downward road. On the other hand there are those who maintain that the desire for narcotics is a symptom of a neur- asthenic tendency. ‘‘So long as there is a call for these narcotics must our race be stamped as degenerate” (Gaupp quoted by Mason, 1910). Says Lydston (1904, p. 200) “Practically, then, inebriety means degeneracy, the subject being usually primarily defective in nervous structure and will-power. It is a noteworthy fact that the family histories of dipsomaniacs are largely tinctured with nerve disorders. Hysteria, epilepsy, migraine and even insanity are found all along the line. In such cases inebriety is but one of the vary- ing manifestations of bad heredity.’”’ Each of these con- trasted views is partial. Whether a person who has taken a first glass of alcoholic liquor shall take another is determined largely by the effect upon him of the first. If the alcohol is THE INHERITANCE OF FAMILY TRAITS 83 very distasteful he will probably not continue to drink; if it wakens a strong desire for more he will probably become (or is) a dipsomaniac.! The result in these extreme cases is deter- mined by innate tastes which are doubtless hereditary. But in most cases the person who takes a first glass finds it indiffer- ent. His subsequent relation to alcohol depends largely upon his associates; but his selection of associates again depends on innate tastes. Some like the steady, quiet, serious youth for their companions; others select the reckless, jolly fellows, careless of the proprieties and—‘‘birds of a feather flock together.’’ The influence of precept is not to be overlooked; this is, however, most important in determining the first drink. No doubt a strong susceptibility to social sentiment restrains many of the border line cases. A strong hereditary bias toward alcohol runs through not a few families of the United States. A pedigree of one such is given in Fig. 49. The neighbors say: “It is a family of drunkards,” yet some of the individuals never touch liquor. The bad environment has its result first and chiefly on those. individuals with an hereditary predisposition toward nar- cotics and this hereditary bias is stronger in some families than others, depending on the nature of the family trait, and it occurs in a larger proportion of the cases in some families than others, depending on the nature of the matings that have occurred in that family. 23. CRIMINALITY In connection with the subject of nervous defect and dis- ease the topic of an hereditary tendency to crime must be 1 Dr. L. D. Mason, head of the Inebriates’ Home for Kings County (N. Y.) tells this story from his experience. He knew of a young man of such ancestry that a dipsomaniac was predicted. For years the youth refrained from drink, and led an exemplary life. Finally, he was operated on for appendicitis and, to hasten recovery, the surgeon gave him some brandy. An uncontrollable appetite was awakened and the man soon died from alcoholism. 84 HEREDITY IN RELATION TO EUGENICS ‘LM a ‘peputur-sjqesj ere Z ‘uerpyiyo 2 Sulureurer JO ‘suiseds jo sKep g 48 palp [ ‘Ppopulur-s[qa9} T ‘uarp[yo Z pey pu’ UeUIOM pepuTUT-o[qeoy @ polmreUr ‘oyoyooye ue ‘9Z ‘AT “WeLp[TYo snornjoros ynq [euLTOU F pey eys woym Aq epoequar oyoyooye ue pewreur ‘Jerourmt pus ourerdma ‘cz ‘AT “pido pepulud-e[qesy [ pus [euoU % pey eys woy kq “oiopuem oyoyooye ue sea pueqsny puoses sey ‘y10ddns-uou Jo} 4jo] OYs UIOYM eu sseziFIyS ING [eUIou & 481g poLLieur ‘2% ‘AT ‘“UaIpTIyO OL pry Avy} pue UUIOM eUIOU & PeleUT FT ‘TIT “Ssprea o7e48 Buleq F ‘oNOINeu [ pus so[lOoqUI ov F ‘graq}0 ayy Jo pur ‘otoyooye ue ‘ET ‘AT ‘oAdumnsuoo v sea ‘ZT ‘AT “Uorpfryd ou pey ynq opoyooys uv potreur ‘TT ‘Ay ‘ferouruat Ayyenxes ‘1oyySnep ysepfo eyT, “Bospyryo IT pey Aoyd ‘F ‘AT ‘JoqyBnep JOY 1048] pore sx °% ‘TIT JO puvqsny oyeurryey[r ay} SB eaoge your eAvy om ‘ZT ‘TIT “Seppo ey, “ooyooye y}0q ‘sus OM} pey oy ‘UeUIOM yeUTIOU & ‘ojIM YsIy sTY AG “90M? poem ,,ejog yonyopooM,, Se UMOTY oPOYyoo[e ssopyjiys vB ‘g qT ‘TewIoU arom ‘TT ‘TIT ‘sieyYysnep om} pus [eUlWILIO pues aoyooye sea ‘OT ‘IIT “8 ‘IIT ‘os apfooquit oy} Osye sea Se [eIOUIUII Ayyenxes sem ‘2 ‘TTT {Sutdsyo ou pey ynq ‘soroyooye q30q ‘goa poled ‘Gg ‘TTT “Joysnep puooss oy, ‘eatdurnsuoo oToyoo|s ue puocoes oy} ‘ae popuru-s[qesy 8 ysuy oy} ‘poLireur TOYA Jo TI0q ‘Suridsyo oyeuNyISeT[I popural-sqoe} Joy}o Z pey os ‘oqoyoore ue Aq ‘ATpamgy §¢ ‘AT ‘PIfyo pexopoo eyeurnytsey[t I pey oys ‘e “TIT ‘weur porojoo @ Aq ‘A[puodes ‘ papurUl-9[q90} T ‘gidduo & pue ondoride 7 ‘erourm puv syoyooye T “uerpiTyo € pey eys woym Aq ‘T ‘TIT ‘ueUr pepulu-s[qooy B qsiq ‘patiem ‘ferouluIT Ayfenxes pue peputu-s[qesy ‘% ‘TIT “epueary qsopjo oy, ‘werprTyo 2 pey Aoyy pues ooyooye ondoride ue pomsreur ‘F ‘T] ‘oyoyooye ue pus ssopytys “g ‘TT ‘roy}0 oyt pue papurui-s[qee} o1eMm F (OT-Z ‘II) UeXP[y g 114} JO “UBUIOM pepuTUl-s[qea} & pleut ‘gyoyoore ‘1exeur-joyseq @ ‘T ‘T “AYTOSquAL YPM VAsToyooTE Jo WOH -eloosse oy} S]ON «‘aBpMoraqny ‘7, forj0Meu ‘ay ‘snourersrm ‘py {iq ‘Asdapide ‘ag ‘Aqrperoururt xes {79 ‘Ayyeurunto fy “oastjoyoore YA poyeroosse {7 ‘Apfloaquil JO sseupepulul-sjqeey qonul Zurstiduoo Ajturey syesnyoesseyy] @ Jo seldipeq— 6p “Sd suseds séopgy | Po PRPARQA BAR IGA LGRABARRRIANGAB —ORTA = Gif , ae aa THE INHERITANCE OF FAMILY TRAITS 85 alluded to. Despite the conservatism of the courts, despite the fact that scientifically ascertained general principles usu- ally weigh less than precedent, the treatment of the criminal has made progress during the past century. It is stated that ‘Mackintosh speaking in the English House of Commons so late as March 2, 1819 said ‘I hold in my hand a list of those offenses which at this moment are capital, in number two hundred and twenty three’ ’”’ (Johnston, 1887, p. 106). Phys- ical severity, frequent floggings, chaining to the floor, unsani- tary surroundings, insufficient and improper food were the elements of a treatment by a society that was exasperated into severity by the realization of its impotent ignorance. Only slowly has the idea of hospitals for insane criminals spread; but though several states maintain great institutions of this sort they still receive a quite insufficient proportion of those convicted of crime. A few pictures of the youth with hereditary criminal in- stincts may properly be quoted here. 1. O. L., female, father and mother both intemperate and degenerate, and always on the verge of pauperism. The patient is cruel to animals and children; thus, she put a cat on a red hot stove, threw knives and stones at playmates, wished to have a small baby to strike and kick; and helped drown a comrade in a bath tub. She is very untruthful and a chronic thief; has fits of temper when she screams, tears clothing, and pulls out her hair; is in a state of chronic re- bellion against the constituted authorities, a trouble maker and inciter of mischief. She talks fluently, is sly and cunning, vain as to her personal appearance and boastful to attract attention. Age 16. This person has committed the crimes of wanton cruelty to animals, petty larceny, truancy, assault and murder. She is a moral imbecile. 2. O. K., male, entered a school for feeble-minded at 9, at the time of the description is 11. He has a bright, knowing, 86 HEREDITY IN RELATION TO EUGENICS intelligent manner, has a fund of general information and is very talkative. He is very cruel to younger children, has an ungovernable temper, is an inciter of discontent and rebellion among the other patients, lies maliciously, ingeniously and convincingly, and steals inveterately and without motive. This child, removed into an excellent school with the best of surroundings, at the tender age of nine reveals striking criminalistic traits which no care can correct. In this case the hereditary history is unknown. In those that follow it has been precisely ascertained. 1 iblylh eo alglohold tbe Fig. 50 3. Figure 50, ITI, 4 is an eleven year old boy who began to steal at 3 years; at 4 set fire to a pantry resulting in an explo- sion that caused his mother’s death; and at 8 set fire to a mattress. He is physically sound, able and well informed, polite, gentlemanly and very smooth, but he is an inveterate thief and has a court record. His older brother, 14, has been full of deviltry, has stolen and set fires but is now settled down and is earning a living. Their father is an unusually fine, thoughtful intelligent man, a grocer, for a time sang on the vaudeville stage; his mother, who died at 32, is said to have been a normal woman of excellent character. There is however a taint on both sides. The father’s father was wild and drank when young and had a brother who was an invet- erate thief. The mother’s father was alcoholic and when THE INHERITANCE OF FAMILY TRAITS 87 drunk mean and vicious. Some of the mother’s brothers stole or were sexually immoral. 4. A healthy man (Fig. 51, II,1) employed on a railroad as a fireman and using neither alcohol nor tobacco married a woman who was born in the mountains of West Virginia near the Kentucky line and who shows many symptoms of defectiveness. She has epileptic convulsions as often as 2 or 3 times a week, has an ungovernable temper, smokes, chews and drinks, is illiterate and sexually immoral. There I » Sooo epLout eae Fig. 51 are 10 children, of whom something is known about 7. One died early of chorea, one of the others (III, 8) seems normal; IIT, 1 has killed two men including a policeman; III, 4 had her husband killed and lives with his slayer; ITI, 6, an epi- leptic and cigarette fiend, convicted of assault; III, 12 has hysterical convulsions and is afraid in sleep;-III, 15 has migraine. The combination in the fraternity of migraine, chorea, hysteria, epilepsy and sexual immorality and tend- ency to assault is striking and appalling. 5. A 10 year old boy (Fig 52, IV, 4) who was precocious as a raconteur at 22 months, does well at school except for inat- tention; is fond of reading and athletics, cheerful, and polite. But he prefers the companionship of older, wild boys and cannot be weaned from them. He lies, runs up accounts in his parents’ name, is acquiring bad sexual habits, and runs 88 HEREDITY IN RELATION TO EUGENICS away from home. He has two fine, studious brothers. His father is a strong character and a successful lawyer, his mother an excellent woman, intelligent and firm. She has a brother who left home at 14 to seek a life of adventure. He finally settled down to a steady life. Their father’s father was erratic. He loved Indian outdoor life, always used an Indian blanket and at over 70 years swam the Mississippi River. He traced back his ancestry to Pocahontas. He has another grandson, III, 2, who is an unruly character with a I OOw@O ae ot oe WV t Fia. 52 roving disposition; he joined the navy and his whereabouts are unknown; his father was a lawyer and a fine character. 6. Another case of truancy (Fig. 53, ITI, 2) is a 7 year old boy whose home conditions are not favorable. His selfish father consorts with lewd women so that his mother has left her husband and now conducts an employment agency. She has hysterical attacks with blank periods during which she may wander. The boy is bright and able but is subject to hysterical attacks; he runs away from school and home and says he does not know why; goes for a long period without food or sleep. His father’s father was erratic, a soldier, very superstitious, used to walk in a graveyard and perform in- cantations at Christmas time. The mother’s father was also THE INHERITANCE OF FAMILY TRAITS 89 erratic and disappeared from home about the time his mother was born. Two of his sons have hysterical fuges and one of them served a term in prison; he is now quite lost to the fam- ily. This is a remarkable history of hysteria with a slight criminalistic tendency. 7. An intelligent and esteemed physician (Fig. 54, II, 2) with training abroad as well as in this country and of a good family (his brother, II, 1, is a college professor and his father a methodist preacher) married a lady (II, 3) of good family, = = POTTED SSeS t 9mos. Fia. 53 with much musical talent, but subject to migraine and for- merly to chorea. They have two sons born in the best of en- vironments. The younger (III, 3) is still in the kindergarten, seems wholly normal, truth-telling and lovable; the other, (III, 2) now 18, developed normally, has had no convulsions, and has never been seriously sick and ordinarily sleeps well. He has regular, refined features and a normal alert attitude and is very industrious. He attends sunday school regularly, has excellent talent for music. At 3 years of age he walked to a near by railroad, boarded a train and was carried 12 miles before the conductor discovered him; since then he has run away very many times. From an institution for difficult boys, where he was placed, he ran away 13 times. He es- capes from his home after dark and sleeps in neighboring door- ways. His mother used to make Saturday a treat day. She 90 HEREDITY IN RELATION TO EUGENICS would take a violin lesson with him and spend the afternoon in the Public Library which he much enjoyed but he would slip away from her on the way home and be gone till mid- night. He is an unconscionable liar. He contracts debts, steals when he has no use for the articles stolen and has been convicted for burglary. Much money and effort have been spent on him in vain. His mother’s father, (I, 3) (of whom he has never heard) was a western desperado, drank hard and was involved in a murder, but finally married a very good 1 NO th f2yrs. Fig. 54 woman (I, 4) and has 2 normal daughters in addition to this boy’s mother. The typical skipping of a generation, seen in these ee grees of the wandering instinct, suggests that it is a recessive, like most neuroses—and strengthens the probability that it is due to a real mental defect. The following case suggests the inheritance of an extremely erotic instinct also as a defect (Fig. 55). A large, healthy man (II, 4) engaged in an engineering pro- fession, has much ability in music and is an inventor. He drinks very little alcohol, has always been a good worker and is highly esteemed by those who employ him. But he is THE INHERITANCE OF FAMILY TRAITS 91 “crazy about women.” He left his first wife and married another, was convicted of bigamy and served a term in prison; later he married a third wife without undergoing the formal- ity of a divorce from the others and was again imprisoned for bigamy. He has had also other, even looser, relations with women. His second wife (II, 5) was a healthy young girl who comes from a Jong lived family. Since her husband deserted her she has had to work very hard to support their children and is much broken down in consequence. She is ae 4 freer Fia. 55 not a strong character, she keeps boarders and is currently believed to be sexually immoral. Nothing is known about her parents nor those of her husband. The daughter of this pair (III, 1), is thirteen years old. She is wilful, refuses to study, runs on the streets, has stayed out all night on two occasions and has been in court as a delinquent. The son, (III, 2), eight and a half years old, has a fair physical develop- ment, but his face is unsymmetrical and his mouth open despite removal of adenoids when he was 5. His speech is thick and rough. He seems dull at times but can brighten up. He has had convulsions. Like his sister he is wilful, won’t learn, and runs on the streets where he sells papers and where he has stolen many articles. He throws stones and 92 HEREDITY IN RELATION TO EUGENICS garbage and despite his tender years he indulges in vile lan- guage, exposes his person to little girls, masturbates and is sexually misused by men. All attempts at reformation have failed,—orphan asylum, home for boys, life on a farm; from all these he runs away and returns to the life he loves. The foregoing cases are samples of scores that have been collected and serve as fair representations of the kind of blood that goes to the making of thousands of criminals in this country. It is just as sensible to imprison a person for feeble-mindedness or insanity as it is to imprison criminals belonging to such strains. The question whether a given person is a case for the penitentiary or the hospital is not primarily a legal question but one for a physician with the aid of a student of heredity and family histories. 24. OTHER Nervous DISEASES a. The General Problem.—The marvellous complex of neurones (nerve cells and fibres), sustentative tissue, and blood vessels that constitute the central nervous system forms, perhaps, the most wonderful mechanism in nature. Little wonder that it should vary greatly in different indi- viduals, or that it should become easily deranged. Such variations in structure and such derangement though ordinarily hidden from view can be inferred from the be- havior of the person. For the general principle holds that every psychosis (or peculiar mental manifestation) has its neurosis (or aberrent nervous basis). Peculiar or abnormal behavior, then, is an index of peculiar or abnormal brain condition. That heredity plays a part in nervous disease is indicated by the familiar fact of high incidence of some or other psychic disturbance in the members of a single family. We have already seen how incomplete mental development is a consequence of the absence of a definite inheritable THE INHERITANCE OF FAMILY TRAITS 93 defect in the germ plasm, such that when the factor that stimulates to complete mental development is absent from the germ plasm of both parents it will be absent from all their offspring. Varied as are the mental conditions of the persons in a family containing feeble mindedness the chil- dren do not ordinarily surpass in mental development the better developed parent. In considering heredity of mental disease we must not forget that what is inherited is not, as in imbecility, a tendency to incomplete mental development, but rather a tendency such that a completely developed and apparently normal mentality is liable under ordinary, or still more under extraordinary, conditions to show disturbance of a temporary or permanent nature. The more intimate nature of this inherited tendency is probably varied. In some cases there is doubtless an idiosyncrasy in the neurones, in other cases there is a lack of resistance to infection or specific poisons, again the trouble may be outside the neurones in the supporting tissue or even in the blood vessels whose walls may be peculiarly liable to weaken and burst; to waste away; to thicken, occluding the lumen and shutting off nutrition to a part of the brain. Before considering the inheritance of specific nervous diseases it may be pointed out that what is inherited is often a general nervous weakness—a neuropathic taint—showing itself now in one form of psychosis and now in another. Especially the lower types of mental defect may be carried in the higher, 7. e., departing least from the normal. b. The Neuropathic Makeup—We have seen (page 77) that imbecility, epilepsy and many forms of insanity are due merely to the absence of some factor. It remains to be considered how they behave amongst each other in heredity. A pedigree worked out by Barr (1907) gives the desired information (Fig. 56). 94 HEREDITY IN RELATION TO EUGENICS mL TA al Pactonicr on ste a) ein : cp a is < ri i eee ee = —| 4 Lal 95 THE INHERITANCE OF FAMILY TRAITS ‘uoriod puey-1J9] ey} moraq ‘e8ed o44 uo posed uaeq sey uorjiod puey-y St 94} pus s[ppIUT oy} UI OMY UI 4NO Uaeq Sey 4 WYO ay} Jo qIZua] ay} Jo yUNOCDDe UG ‘ALON ‘[BULION [[@ 918 UsIp[ppueis Mey], “etaeuMosdip peounouoid ® YM olj0InNoU OIG Z PUB [VUNIOU oe Z USIP[IYO ey} JO *Y00}S poo jo ueul es polreul pue sYoInou si ‘guee ‘g ‘TIT ‘OUBSUI SEM OYM ] PUL O[IOOQUII Se OYA PIV? T pey pus “(api ysy Aq puvgsny s,JoysIs Pilg} JO uos) ovlIpucysodAY & poliieUE ‘[euUTIOU Jassey ‘TZ ‘AJ ‘ensst ou pey qnq oor} poureu ‘odode ue ‘GT ‘AT ‘omorneu _ ‘ouvsul orem Z ‘UaIp[IYD ¢ JO ‘“SeUIT} [BIOARS VIULUT pey JfasuTy pry OYM 3904s O1JOINU Jo ULUI B palieUl ‘TeuIoU Joss0y ‘sousy ‘FT ‘AT “Aouvjur ul pelp ppm T ‘oromou sg z ‘fewsou sfhoq F ‘uaIpfiys 6 pey pus yoo} poos jo uvulom vB pole ‘euou ‘ZI ‘AT ‘“oUBSUL [ pu OTJOINOU Z ‘[eUIIOU e1aM Z ‘USIP[IyO G JO ‘PIEya ysay jo Yq ye AyrUesut pesediond pey ‘yo04s pood jo ueu B patireur ‘orjomMeu ‘QT ‘AT ‘[eudtoU oJoM G pue Aouezur Ul perp [ ‘oromneu T ‘(ordou & Aq peonpes) oNdopida sem | “UsIp[IyD g JQ “JeJRIBYD ssoo] Jo URUIOM O1}OMouU B pollIeUr ‘IVT -[hoed ynq ‘euou FEsuuTy ‘gz ‘A ‘WON YSep[O OY, ‘ol}OINeU a10M ATUO UeIpPTIYO 8 jo yno Z pus’ yoo oyOMeu powseU ‘orydoT ride ue ‘g ‘AT ‘BIAY[O “Ioysis JOY ‘[BUIIOU [[@ AJoM UdIp]Tyo IY} pus ‘yo03s poo oul poLizeur [fe yNq oMomnou seM T ATUO ‘ueap[rya moj Joy JQ “Y00}s poos OFU polireu ‘peysyduroooe pue [nyiyneeq Aypeuordaoxe ‘feuiou Jesiey ‘g ‘AT ‘Are *Y90}8 POOS Jo WOUIOM polI -IUl SUS OTJOINEU OM4 I0YIQ “ATWO pP[Tyo uLog-]]14s suo peYy pus ‘oTJoInSU os[e “Qo]TeY & peLizeU ‘Gy ‘A ‘UOs OT}OINeU JoyOUYy ‘[euiou [ puw Sunof palp oy uaiplyo ¢ pey soy} pue ‘AToreys oOIMeu v WOT] Sunads “yo,rey B ‘te}ORVIeYD BsOo, JO UBUIOM ® pote ‘6 ‘A ‘suOs o1}0MeU ese} JO oUQ ‘UaIp[Myo [euIou g pu oljomeu F pey ‘4904s pood jo ueu v palleUr ‘OToIneU Jlesrey ‘eooogey ‘p ‘AT “Ulsnod pepurul-s[qes} v sey puUe s[loequI! Ue SI ‘¢ jo ‘pyTyD aUQ ‘aflooquII Ue se IOy}OIq asOyM pus SUBSUI-IMOS SVM JOY}E} OSOYM SUSU! PoIp OYA ULUT B PoLIIVUl sloyYSNep 91}0MeU sseq} Jo ou) ‘[BUIIOU | PU d1}OIMEU SIO }0 g fouesut st ‘g ‘A ‘auo ‘UaIp[Iyo G Jo ‘eUWSUT SI JoY}JOIq OsOYM UBUIOM ol}OINeU & palizeu ‘pejdioutdun pue omomou ‘g ‘AT ‘adioan uos ysep[Q ‘orydayide Z pue ‘oNomou F ‘[euI0U PF ‘WoIPTYyS OT psy ‘4903s poos oyur potmreur ‘ouvsut Fasioy ‘e ‘TIT ¢ ‘papuru-s[qae} eyvorpul 4j9] eq} ye poyxov[q sjoquiAs ‘sorjdojide oyeorpur Jfey IeMoT 9y4 UO pexoR[q sjoqurcs ‘suoszed oromou yuaseided Fey YSIL oY} UO payovyq sjoquids /AyruesUr oyYBoIpUT sjoquIAS YR [MY “TA—AT "we ‘oljorneu ‘g ‘T]] ‘euvsut ‘g ‘TIT ‘yeusou | ‘T]] fouesut ‘g ‘TTT foyomeu ‘g ‘Ty feuesut ‘T ‘TIT ‘xejdunis Apjueptas ynq jeusou ‘Z ‘T ‘Ty ‘feudsou ‘g ‘Tt fouesul ‘{ ‘J—‘dnoyeur oryyedoineu jo Ayres @ Jo oalsIpag—g¢ ‘DI 96 HEREDITY IN RELATION TO EUGENICS This pedigree contains 22 significant matings (7. ¢., that yield more than one child). The products of these matings are summarized in Table IX. TasBie IX PRODUCT OF VARIOUS MATINGS IN BARR’S PEDIGREE Martine OFFSPRING Nos. N Ne F E I X Still-births Neurotic X neurotic 4 1 3 1 Neurotic X neurotic 16 61 3 Neurotic X epileptic 7 4 2 2 Neurotic X insane 15 2 1 1 Insane X normal 2 4 2 j 10 1 2 Neurotic X normal 3 2 2 5 2 4 8 2 2 1 11 1 1 12 1 1 13 7 (22 2 Neurotic X unknown 18 2 | 20 1 1 1 Normal X normal 1 2 3 6 3 1 1 9 2 1 14, 17, 19, 21 16 E, epileptic; F, feeble-minded; I, insane; N, normal; Ne, neurotic; X, un- known. In Table IX there is no marriage of two insane persons. Where a nervous person marries a neuropath, of 11 known offspring 6 are normal and 5 neuropathic; when two neurotic marry, 2 out of 6 children are normal and 1 insane; when an insane and a normal marry, of 13 children 4 are normal and 2 insane; when a neurotic and a normal marry, of 28 children 16 are normal, 9 nervous, 1 feeble-minded and 2 insane. Even some normal parents (of this strain) have THE INHERITANCE OF FAMILY TRAITS 97 insane or epileptic children. One sees what a variety of gametic conditions may be carried by a “nervous” or even a “normal” person, just as blue eyes may be carried by brown eyed parents, or light brown hair by dark haired parents. ad Lye A “nervous” person is thus fre- quently simplex in the factor that makes for mental strength and is apt to carry defective germ cells | b e 4 (Figs. 57-59). Lal c. Cerebral Hemorrhage.— How- Fic. 57.—Pedigree of “nervous trouble.” I, 2, was ever numerous the causes that typically affected and I, 4 weaken the walls of the cerebral Svffered from migraine. I, : 1, had the same nervous trou- arteries or raise abnormally the bie. Of three grandchildren pressure upon them, there can be Whosurvive, lalready shows , : : at 6 years, a tendency to- little doubt that hereditary predis- ward nervous weakness. F. position plays an important part. peas (Figs. 60 and 61). Cerebral hemorrhage is commonly found in the parentage or grandparentage of the mentally i‘ ne rObnbteeboue tous nh bed bed Fia. 58.—Inheritance of nervousness and brilliancy. I, 4, is subject to headaches and nervousness. Her daughter, II, 7, is similarly affected. She married a man, II, 6, who has had temporary attacks of paralysis. One of their children, II, 2, has nervous prostration and one, III, 3, is subject to head- aches and nervousness. F. R.; Cla. 3. weak as well as brilliant. (Fig. 61). See also arteriosclero- sis, page 162. d. Cerebral Palsy of Infancy—This disease, of obscure origin, affects infants within a few years of birth; it leads 98 HEREDITY IN RELATION TO EUGENICS I OO OO I roeah Fie. 59 Fig. 60 Fic. 59.—Pedigree of a family with nervous disease. I, 3, was a heavy drinker; I, 4, died of apoplexy after suffering from paresis. The father was normal, but he had a brother, II, 1, who was eccentric and committed suicide, and a sister, II, 2, who was a good linguist but deteriorated mentally. The mother, II, 4, is normal but she had a brother who while a civil engineer and excellent draftsman was alcoholic, and a sister who was a good musician. One.child, III, 2, is suffering at 23 from dementia precox. F. R.; Coi. 1. Frc. 60.—Pedigree of a family with high incidence of cerebral apoplexy. The father and mother, I, 1 and 2, both have apparently a tendency toward cere- bral congestion. I, 2, had recently had an attack which was relieved by nasal hemorrhage. Two of the mother’s brothers, I, 3 and 4, died after a brief attack of apoplexy. Three of the daughters have died of the same disease at 32, 30 and 46 years respectively; the remaining suffers from cerebral congestion. Harrineton, 1885. Lim ® 3 bdo 105 mn DUD eDOd my Fig. 61 Fig. 62 Fic. 61.—Pedigree of a family with ‘“‘nerve weakness.” The father’s father, I, 1, had a “nervous weakness,” his wife died at 28 of encephalitis, the mother’s father, I, 3, was subject to apoplexy and died of a stroke at 71. The father, II, 3, and all of his fraternity had encephalitis—the father three times— and one died of it, while the others were left with a nervous weakness. The children were not vigorous. III, 1, had always a low vitality and died at 8 years; III, 3, had a low vitality and died at 14 of ‘‘dongestion of the lungs”; III, 4,was feeble-minded; III, 5, a laborer, suffered much from “bowel trouble”; III, 6, has a nervous weakness; and III, 7, engaged in housework and, with III, 2, is the strongest of the family. Fic. 62.—Pedigree of a family with cerebral diplegia. The father in the central mating, II, 3, has been three times married. By two of the marriages THE INHERITANCE OF FAMILY TRAITS 99 to general paralysis of one or both sides and, in later develop- ment, is associated with feeble-mindedness. Pedigrees are given by Dercum (1897) Fig. 62, Pelizaeus (1885) Fig. 63, Freud (1898) and others. Since the tendency is carried by normal persons and since (as in Freud’s case) it is apt to occur with consanguineous marriage it is probably due to a specific defect. To 4... 65 sus. avoid the reproduction of the disease, mar- trates the pedigree riage with unrelated blood is essential. A eupaatert gars e. Multiple or Disseminated Sclerosis.— plegia who married This is a diffuse degenerative disease of the 5 peepee a sister similarly spinal cord. It leads to tremors in the arms affected. Both and trunk, disturbance of speech and even- arg eae tual paralysis. It is usually not regarded as 1885. hereditary but an interesting pedigree showing its appear- ance in 3 generations has been investigated by Merzbacher (1909), Fig. 64. As the pedigree table shows, the disease is transmitted through unaffected females. The eugenic conclusion is, consequently, that even unaffected females who have af- fected brothers should not have children. f. Hereditary Ataxy (Friedrich’s disease)—This disease causes a slowly but surely progressive loss of directed move- ments, first of the legs and then of the arms; speech becomes elusive and indistinct; scoliosis (curvature of the spine) may appear and the feet become drawn up. These symp- toms accompany a degeneration in the upper part of the spinal cord. he had only normal children, but by the third (to a normal woman who had a first cousin, II, 5, with cerebral diplegia) he had 4 sons of whom 3 were affected with this disease. The eldest, III, 3, was normal until 16 months old, then had general convulsions, after which spastic symptoms gradually ap- peared, becoming pronounced later. Now he can walk only a few steps and is quite idiotic. The third son was normal until 2 years old, but is now deteriorating after an attack of measles and the youngest, only 2 years old, has just become diplegic and epileptic. Dercum, 1897. 100 HEREDITY IN RELATION TO EUGENICS Some extensive pedigrees of ataxy have been published. One of the most extensive is by Mott (1905). It is repro- duced in Fig. 65. ee Sh ines Fig. 64.—Part of E1chotp-FLEMING-STossEL-HERZER pedigree showing multiple sclerosis (black symbols). One notes the skipping of a generation (indicating a recessive trait). The trouble is usually carried by unaffected females (heavy circles) and appears in their sons. Interesting because same family was independently noted by two neurologists. Prxizanus, 1885; MERz- BACHER, 1909. Since, as the pedigrees show, normals may have affected offspring the disease is probably dependent, as in insanity, on the lack of something necessary for normal development. The disease seems to be in no way sex-limited (Fig. 65). oe da 5 a dn aa isa $20 deaddd ee Fia. 65 .—Pedigree of a family with hereditary ataxy (black symbols). Consorts not in direct line mostly unknown. Note that affected persons have (for the most part) one affected parent; the trouble is due to the presence of some positive character. Mort, 1905. The eugenic teaching is that affected persons and also normals of the affected fraternities should marry only out- side the strain. Whether all cases of atactic offspring of one normal parent are derived from consanguineous mar- riage is still uncertain and warrants hesitation in advising the marriage of any atactic person. THE INHERITANCE OF FAMILY TRAITS 101 g. Méniére’s Disease is apparently due to a disturbance in the auditory nerve or its centre. It is accompanied by dizziness and roaring in the ear, often so severe as to force the patient to fall to the ground. Simon (1903) de- scribes a family with these symptoms, consisting of an af- fected father, son and two daughters. The onset of the attacks varied from the 25th to the 50th year. h. Chorea (St. Vitus’s dance) is a disease of the cere- ) gic 1! 21 3 V all + convulsions Fic. 66.—Pedigree of chorea (black symbols). II, 1, became affected with chorea at 8 years before his death; II, 2, has suffered many years; 4 other brothers and sisters are healthy. II, 3, became sick at 35 and suffered until her death at 46; she also had a marked loss of memory and died in a hospital. III, 1, is healthy; III, 2, suffers from severe sick headaches. III, 3, has chorea. IV, 4, is 11 years old and has been afflicted with chorea and epileptic fits for past 2 years. Her sister is still healthy at 10 years. Jouty, 1891. bral hemispheres characterized by involuntary, irregular movements of the limbs or other parts of the body. It commonly occurs in families with neuropathic make-up. Ordinarily the disease appears in the children and ends in recovery; occasionally it appears only later in life and runs various courses, sometimes ending in death through exhaus- tion. This disease is commonly sharply separated from Huntington’s chorea, but transitional conditions occur. A case cited by Jolly is shown in Fig. 66. In this case noth- ing is known about the first generation; the second com- prises 4 normals and 3 affected persons, 2 males and 1 102 HEREDITY IN RELATION TO EUGENICS female. II, 1 became affected with chorea ‘8 years before his death”; II, 2 ‘“‘has been affected for many years’’; II, 3 became ill with chorea at 35 and suffered until her death at 46. These look like cases of Huntington’s chorea. III, 2 suffers from migraine; III, 3 has chorea, IV, 1-3 died at birth of convulsions; IV, 4 at 9 years began to show chorei- form movements. These have continued for two years until the present time. This girl also has epilepsy; but her chorea has appeared at the age for St. Vitus’s dance. i. Huntington’s Chorea—This is said to be a “rare” disease in Eurdpe, but not so in the United States. It is characterized by appearing typically first in middle life and progressing with ever increasing disorder of move- ments until dementia and death occur. It affects both sexes about equally. Two pedigrees are given in Figures 67 and 68. The method of the inheritance of this disease was recog- nized by its original describer, Dr. George Huntington. He states that those exempt from it cannot transmit it. An examination of the extensive pedigrees shows only one exception to his rule and this a doubtful case. Hunting- ton’s chorea is, consequently, a typical dominant trait, the normal condition is recessive; or, the disease is due to some positive factor. The eugenic lesson is that persons with this dire disease should not have children. But the members of normal branches derived from the affected strain are immune from the disease. This disease forms a most striking illustration of the principle that many of the rarer diseases of this country can be traced back to a few foci, possibly even to a single focus; certainly in this case many of the older families with Huntington’s chorea trace back to the New Haven Colony and its dependencies and subsequent offshoots. The subject of foci of origin of traits will be discussed more fully later (page 181) THE INHERITANCE OF FAMILY TRAITS 103 j. Hysteria—This term is applied to a variety of symp- toms that indicate a functional disturbance of the psychic centres usually "oh with a derangement of the lower GO Opts oyeioneia PN et decendants all normal z Iv several normal Fic. 67.—Pedigree of a family showing Huntington’s chorea. Affected persons (indicated by black symbols) are always derived from affected parents. From original data furnished by Dr. 8. E. JevLirre; Smi-family. cerebral or spinal centres. The psychical symptoms ap- proach mania on the one hand and show a more or less complete loss of the moral sense on the other, so that many L mO 1 a be ‘e = . foe ft we ne tide lislial 15 Fic. 68.—Pedigree of a family with Huntington’s chorea. All affected persons (black symbols) have at least one affected parent. Hamiuron, 1908, p. 453. cases of larceny, assault, and sexual immorality are conse- quent upon this disease. The emotions usually are dis- turbed. The motor symptoms are frequently profound. 104 HEREDITY IN RELATION TO EUGENICS Thus paralysis, or spasmodic contractions, or even convul- sions not unlike, if not identical with, those of epilepsy, make their appearance. The greatest social importance of hysteria lies in its re- lation to crime and responsibility. A large proportion of “criminals”? doubtless are in need of hospital care. The family history of the offender will give the best possible clue to his probable mental condition and, where a ‘‘neuro- pathic blood” is evident, the patient should be segregated, not to punish him but to care for him at the expense of that ‘‘society’’ which still permits his kind to breed unrestricted; and to prevent, or at least to limit, the further spread of his tainted germ plasm. In studies made on 175 families containing epileptics which the author has had the privilege of making with the cooperation of Dr. David F. Weeks hysteria was frequently found associated with chorea, migraine and a ‘‘neurotic” condition in the parentage of epileptics and in the offspring of an epileptic or insane parent married to a normal. It acts like a condition induced by a simplex determiner such that the patient produces some defective germ cells. 25. RHEUMATISM Rheumatism, as is well known, is often associated with chorea. An example of such association is given in Figure 69. A second instructive case is that cited by Cheadle (1900). A man who had subacute arthritis and muscular rheumatism and whose sister died at 8 years of heart disease following acute rheumatism and chorea married a woman who had suffered from acute rheumatism, heart disease and chorea and had had a nephew affected with rheumatic fever and heart disease and a niece with subacute rheumatism. The child of this pair at 9 years of age had chorea in a most THE INHERITANCE OF FAMILY TRAITS 105 severe form, repeated attacks of inflammation of the heart and pains in joints with formation of nodules beneath the skin. Finally the girl died a victim to extreme, uncontrol- lable rheumatism and chorea. The exact laws of inheritance in these cases are not clear and eugenic instruction cannot be drawn from them. I - alal sl ol al sl al I Fic. 69.—Pedigree of family showing chorea and rheumatism. I, choreic at 15 years; still has slight twitchings; II, 2, is not choreic but is subject to migraine and has had several attacks of rheumatism. He has had 2 daugh- ters and 2 sons. III, 1, is 18 years old and since her eighth year has had chronic and severe chorea; at 12 she had an attack of rheumatism and since then attacks of rheumatism and chorea have alternated. Her elder brother, 16 years of age, was attacked a year before by chorea which lasted 2 months; recently has had another attack preceded by rheumatic pains. The third child, III, 3, now 13 years old, has had no rhematism but was first attacked by chorea at 12 and has had other attacks since. The youngest, III, 4, now 11, had a first attack of chorea at 8 years, lasting 2 months; a second attack at 10 and a third recently; in his eighth year he had articular rheumatism. APERT, 1907, p. 235. 26. SPEECH-DEFECTS While the minor speech defects of stammering, stuttering, lolling, lisping and poltering correspond to no yet recognized abnormality of the central nervous system or organs of articulation, nevertheless, aside from imitation, they clearly have an hereditary basis and while the slighter grades may be cured by practice the more profound disturbances remain a permanent affliction. Especially are these defects found in children of a neuropathic inheritance and, in such, yield the strongest evidence of inheritance. The exact method of inheritance of stuttering will not 106 HEREDITY IN RELATION TO EUGENICS become known until more extensive pedigrees of stuttering families have been obtained. Two pedigrees have been obtained (Figs. 70, 71). e Trt ‘ Fo) . 7 ; Can 4 : a jue con ce b $585 o0d0 2 Fia. 78.—Pedigree of “coralliform” cataract. Affected persons repre- sented by black symbols; co’, male; 9, female; numbers in circles indicate number of individuals. From Nerruzsaip, 1910. described, with 150 children, of whom 70 per cent were affected. The details of the condition and the degree of injury to sight vary from strain to strain (Fig. 79). In this case, also, it appears that the defect is due to some positive factor and that when present in either parent it will be present in about half the offspring; but if present in neither parent it will be absent from all descendants. The eugenic teaching is clear; persons with displaced lens should have no children; but normal persons of the same strain will not reproduce it in their offspring. f. Degeneracy of the Cornea.—While several causes of corneal opacity are known that seem not to be hereditary, THE INHERITANCE OF FAMILY TRAITS 113 18 cases of hereditary degeneration of the cornea are re- corded. So far as the studies that have been made go they indicate that persons with such hereditary corneal opacity should not have children but that normal members of such a strain will have normal offspring. g. Glaucoma.—This is a swelling of the eyeball due to excess fluid in the chambers of the eye. It appears to de pend upon the presence of something that prevents the escape of the fluids of the eyeball. In the study of the in- heritance of this disease we meet with the difficulty that, like cancer and many forms of cataract, its outset is late in @ * ote st Fic. 79.—Pedigree of a family with dislocation of lens, resulting in ‘imper- fect vision, vertigo, flashes of light, etc. The amount of displacement varies in the different individuals. In the third generation 2 individuals are af- fected in one eye only but in all other cases both eyes are affected. Lewis, 1904. life—so that many persons with potential glaucoma die before realizing it. However, the age at onset is variable, in some families high and others low; but in the children the onset is frequently earlier than in the parents; thus, in one family the father shows the disease at 70, his daughters at 45, and 40; in another case father is attacked at 49 and his sons at 18 and 16; again, a father has glaucoma at 60, his 4 chil- 114 HEREDITY IN RELATION TO EUGENICS dren at from 55 to 40; and a mother is affected in one eye at 60 and the other eye at 81, while her 3 children are affected at 60. In onefamily strain, Von Graefe noticed an unusually long bide Ot So Sa but Sink ied, Fie. 80.—Pedigree of family with glaucoma, showing simple dominance of the trait. In I, 4, the disease appeared at 40 years of age; in II, 2, at 28; in II, 4, at 25; in generation III, at 28 to 17 years—an extraordinarily early age. Hows, 1887. prodromal stage (10 to 15 yrs.), before the fully developed attack. This is one of the special family strains. Glaucoma is said to have various inciting causes. The type that follows a characteristic inflammation shows the Fie. 81.—Pedigree of family with glaucoma, percentage of incidence of disease small, owing perhaps to early deaths (?). In the first generation the disease began at 71 years, in the second at 40; in the third at between 25 and 30 years. NETTLESHIP. best evidence of heredity. A pedigree or two will illustrate the method of its inheritance (Figs. 80, 81). The eugenic teaching is rendered more difficult by the fact that glaucoma usually first appears toward the end of the reproductive period. But certainly affected persons THE INHERITANCE OF FAMILY TRAITS 115 should avoid having children, while non-affected may marry if the disease first appeared in the grandparents at 50 or after. If it appeared earlier it would seem to be prudent for the normal persons to delay reproduction until within ten years of the time that the defect appeared in their parents. Then if no trace of the disease has occurred they may have children with impunity. h. Megalophthalmus or protruding eye. A rather rare disease of whose inheritance there can be no doubt, although the exact method of that inheritance is uncertain. Persons with a well marked case had best avoid reproduction. i. Nystagmus, or “‘swimming eyes.” This is due to spasmodic contractions of the eye muscles and may or may not be associated with other defects of the eye. The dis- orders with which it is most apt to be associated are: strabis- mus, retinitis pigmentosa, coloboma, albinism, microphthal- mus and cataract. In some of the pedigrees that have been published (Clarke’s, 1903), nystagmus, like optic nerve atrophy, is not expressed in the (simplex) females ! but is expressed in all males capable of transmitting it. When it is unexpressed in the males of the strain, it will probably not (in non- consanguineous marriages) appear in the offspring. But mar- riages of even non-affected females (unless from large fami- lies of non-affected brothers) and of all affected males are pretty certain to yield offspring with nystagmus. k. Paralysis or imperfect development of the muscles of eye and lids.—This includes ptosis, or drop of the upper eye- lid; epicanthus, a fold of skin passing from nose to eyebrow over the inner corner of the eye; blepharophimosis, or small- ness of opening of eyelids; ophthalmoplegia, or paralysis of eye muscles; strabismus or squinting. Every one of these peculiarities shows clear evidence of heredity. 1In other families nystagmus appears also in the females. 116 HEREDITY IN RELATION TO EUGENICS OC BO 8 HODO0000 rie i Fiq. 82.—Pedigree of a family, every affected member of which (black symbols) has drooping eyelids, a fold over the inner corner of the eye, and nar- row eye opening. VIGNEs, 1889. One family pedigree is reproduced in Fig. 82. This is remarkable because every affected person showed the same combination of characters, namely, drop of upper eyelid, epicanthus, and ophthalmoplegia. In Cutler’s case (Fig. 83) the parents are first cousins; all affected persons have strabismus. Expectation in this group of cases is that an affected person will have affected off- spring but that two normal parents will rarely have off- spring with the defect, even though one belongs to the defective strain. 1. Pigmentary degeneration of the ret- [ ] | ina (retinitis pigmentosa).—This degen- erative process is accompanied by an Fic. 83.—Pedigree atrophy of the optic nerve and leads to ae be | in witch eventual blindness. It is frequently as- eens and both Bd sociated with consanguineous marriage, alae pet 27 per cent of the marriages which yield dren are similarly af- it being (according to Feer’s list, 1907, fected. CUTLER. c p. 14) consanguineous. The method of inheritance is well illustrated by Fig. 84 which is a portion of a chart prepared by Nettleship. This figure illustrates the general law of this disease; namely, that two normal first cousins THE INHERITANCE OF FAMILY TRAITS 117 ‘eT ‘d ‘O161 ‘dIHSaILLaN «‘“Sutrdsyo poyooyeun AjUO oAey sjuared [BULIOU OM} JV} OJON = ‘S[ENPIAIPUT poyoyes ‘HOV “esojueaid sIyTUTJeI JO soUBYLIEYUI Jo poyyeu Sutmoys diqseryyeN Aq peyiduroo soidiped & jo JueUdeI] Y—'F8 ‘PLT “epayoajjeun spuepuaosap [Te > +Bunof parp- " eta eee a 118 HEREDITY IN RELATION TO EUGENICS parents produce no abnormal children. The condition that makes for retinitis is something added to the normal con- dition. The extent of the degeneration varies with the family. In a pedigree recorded by Leber (Fig. 85) the characteristic, throughout the family, was an increasing dimness of vision accompanied by night blindness; but later the degeneration was stayed. The eugenic instruction is clear. An affected man or woman should not marry even into stock without taint of retini- tis. Above all, in retinitis stock, cousins, especially if affected should by no means marry. Fic. 85.—Pedigree m, Night Blindness (hemeralopia). — of retinitis pigmentosa aoe : : in a family in which This disease is accompanied by no loss of oe perception of form, but at sunset the af- ness becomes com- fected persons must cease working. Ar- plete. Luper, 1871. t¢ifcial light helps little unless very in- tense. The lamps of the street are of no assistance in guid- ing these people at night. Eventually, in most strains, the affected persons become totally blind often with a retinitis. This disease is probably due to a defect in the brain and not as has been suggested merely to lack of the visual purple of the retina (Bordley, 1908). Through the researches of Cunier (1838) and Nettleship (1907) we have a pedigree of a night blind strain that is the most extensive that has yet been compiled for any disease. It includes 2,116 persons. A part of it is reproduced in Fig. 86. Fig. 87 is a pedigree of an American (colored) family furnished by Dr. Bordley. The disease is due to a positive factor. The normals lack this factor. Usually, however, the factor must be duplex THE INHERITANCE OF FAMILY TRAITS 119 21 jas \ 20 [a] 28 3 aa tt 08 Bld 150 Ql 80 867230 ar “ eos | m1 609 } Q? $3 r201 202-228 ‘aay % 77 80 813 12d 3aZo ‘J