CONTENTS 



CHAP. 



I. Introduction. Relation of Heredity to other branches of 



knowledge. — The questions to be answered . page 1 



II. Variation. Occurrence and kinds of Variation. — Con- 



tinuous variation and methods of study. — Discontinuous 

 variation. — Inborn and acquired characters . 7 



III. The Causes of Variation. Mutation. — Action of en- 



vironment on body and germ-cells. — Variation on cross- 

 ing. — Relative importance of ' inherent ' and ' acquired ' 

 characters 22 



IV. The Statistical Study of Heredity. Two methods of 



studying Heredity. —The biometrical method. — Corre- 

 lation and Regression. — Parental correlation and the 

 Law of Ancestral Heredity. — Heredity in 'pure lines' 

 (Johannsen etc.). — Inheritance of 'mental and moral' 

 characters in Man. — Eugenics .... 32 



V. Mendelian Heredity. Mendel's Law illustrated.— Segre- 



gation and Allelomorphism. — Crosses concerning more 

 than one pair of characters. — Examples of Mendelian 

 characters in Plants and Animals. — Combs of Fowls. — 

 The Andalusian Fowl 52 



VI. Mendelian Heredity {continued). The Inheritance 



of Colour. Concurrence of two factors in the pro- 



