Magazine_, March, 1908.]

The stock illustrations from isolated communities have been omitted as
too difficult to verify, and little space has been given to the
results of the inbreeding of domestic animals, for although such
results are of great value to Biology, they are not necessarily
applicable to the human race.

The writer regrets that it is impossible here to acknowledge all his
obligations to those who have assisted him in the preparation of this
work. Such acknowledgement is due to the many genealogists and other
friends who have kindly furnished detailed cases of consanguineous
marriage. For more general data the writer is especially indebted to
Dr. Alexander Graham Bell, to Dr. Martin W. Barr, to Professor William
H. Brewer of Yale University, and to Dr. Lee W. Dean of the University
of Iowa. In the preparation of the manuscript the suggestions and
criticisms of Professors Franklin H. Giddings and Henry L. Moore have
been invaluable.

G.B.L.A.

MARCH, 1908.

CONTENTS

CHAPTER I

INTRODUCTION

Problems to be Treated--Degrees of Consanguinity--Literature of the
Subject--Noah Webster--Bemiss--Dally--G.H. Darwin--Huth--Bell--Legal
Status in the United States--Methods of
Investigation--Genealogical--Personal--Isolated Communities

CHAPTER II

RATIO OF THE CONSANGUINEOUS TO ALL MARRIAGES

Previous Estimates--Mayo-Smith--Mulhall--Darwin--Application of
Darwin's Method to American Data--Direct Method--Consanguineal
Attraction--Same-name and Different-name Cousin Marriages--Summary

CHAPTER III

MASCULINITY

Constancy of the Sex-ratio--Consanguinity and Masculinity--Theory of
Westermarck and Thomas--Duesing--Gache--Negroes in the United
States--Genealogical Material--Other Compilations--Summary

CHAPTER IV

CONSANGUINITY AND REPRODUCTION

Theories of the Effect of Consanguinity upon Offspring--Comparative
Fertility--Statistics from Darwin and Bemiss--Genealogical
Statistics--Youthful Death-rate--Degeneracy--Fallacies in the Work of
Bemiss--Isolated Communities--_The Jukes_--Other Degenerate
Families--Scrofula

CHAPTER V

CONSANGUINITY AND MENTAL DEFECT

Idiocy and Insanity--Inheritability of Mental Defect--Intensified
Heredity--Barr's Investigations--Other American and English
Data--Mayet's Prussian Statistics--Genealogical Data

CHAPTER VI

CONSANGUINITY AND THE SPECIAL SENSES

United States Census Data--The Blind--Consanguinity of Parents--Blind
Relatives--Degr