Part Iii. Family Studies in Heredity of Build 51

A. Statement of problem 51

B. Discussion of special matings 51

CLASS I. Both parents slender 51

Mating 1. One parent is very slender of slender stock; the other slender 51

Mating 2. Both parents are slender, of slender stock 53

Mating 3. Other slender × very slender matings 54

Mating 4. Other slender × slender matings 56

Summary of slender × slender matings 68

CLASS II. Both parents fleshy 69

Mating 1. One parent is very fleshy, the other fleshy of fleshy stock 69

Mating 2. Both parents fleshy of fleshy stock 77

Mating 3. Other very fleshy × very fleshy matings 80

Summary 85

CLASS III. Mating of slender with fleshy stock. The F₁ generation 86

Mating 1. One parent slender, of slender stock, the other fleshy of fleshy stock 86

Mating 2. Other slender × fleshy matings 93

Mating 3. Very slender × very fleshy 97

Mating 4. Slender × very fleshy matings 98

Summary 105

CLASS IV. Matings of probably heterozygous parents. The F₂ generation 107

Mating 1. Both parents either medium or fleshy, and probably carrying gametes for slenderness as well as fleshiness 107

Mating 2. Other medium × medium matings 118

Summary and discussion 119

CLASS V. The back cross 119

Mating 1. Heterozygous medium or fleshy × slender 119

Mating 2. Fleshy × heterozygous fleshy parents 132

Summary and discussion 140

C. General discussion 141

Heredity and environment in build 141

Endocrine glands as links between chromosomes and somatic qualities 145

Evidence of segregation in the heredity of build 146

On the number of factors involved in fleshy build 149

D. Summary of conclusions 152