CONTENTS 



PART I. 



CHAPTER PAGE 



I. Introductory. Mendel's Discovery . . . . i 



Introductory — Some pre-Mendelian Writings — Mendel's Discovery — 

 Dominant and Recessive— Segregation. Allelomorphism — Homo- 

 zygote and Heterozygote. Purity of Type. 



II. The Material Investigated . . . . . .18 



List of Structural Characters in Plants and Animals — List of Types in 

 which the inheritance of Colour has been studied — Preliminary 

 Deductions — Dominance and heterozygous characters — Mendel's 

 system distinguished from that of Galton. — " 



III. Numerical Consequences and Recombinations . . 57 



Representations of the Fg Generation and Novelties due to Re-combina- . 

 tion of Factors — Compound Characters — Combs of Fowls — Hetero- 

 stylism — White Flowers from Red x Cream. 



IV. Heredity of Colour 74 



Factors determining Colours : the Ratio 9:3- 4— The " Presence and 

 Absence " Hypothesis. Epistatic and Hypostatic Factors — Colours 

 of Mice — Pied Types — A Dominant Piebald. 



V. Heredity of Colour {continued) . . . . . 88 



Albinos giving Coloured Offspring ; Reversion on Crossing — Various 

 Kinds of Whites — Stocks— Orchids— Pigeons— Fowls — Primula. 



VI. Heredity of Colour {continued) .... 



Eye-Colours. Variations in Colour of the Iris— Deficiency of Eye 

 Pigments in some Coloured Types. 



VII. Heredity of Colour {cofitinued) . . • • 



The Genetics of Yellow Pigments in certain Animals. Yellow Mice not 

 breeding true— The Case of Basset Hounds and the " Law of An 

 cestral Heredity." Relation of this Principle to Mendelian Rules. 



VIII. Heredity of Colour {continued) .... 



Various Specific Phenomena in Colour-Inheritance. Relation of Colour 

 to Hoariness in Stocks. Miscellaneous Cases. Colour of a Special 

 Part controlling that of other Parts— Summary and Discussion— 

 Sublraction-Slages. 



107 



115 



132 



