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CONTENTS 



PART I. 



CHAPTER PAGE 



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



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

 Domiaant and Recessive — Segregation. Allelomorphism — Homo- 

 zygote and Heterozygote. Purity of Type. 



II. The Material Investigated i8 



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 (contmtied) 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 (continued) .... 



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— 

 Subtraction-Stages. 



107 



IIS 



132 



