CONTENTS. 



Page 



PREFACE 



PART I. EAR-SIZE 9-35 



Introduction 9 



Characteristics of lop-eared rabbits; sterility and its inheritance .... 9 



Growth-rate of lop-eared and of short-eared rabbits in size and in ear-length 12 



Matings of short-eared rabbits inter se 14 



Matings of lop-eared rabbits inter se 16 



Cross i. Lop-eared female X short-eared male 18 



Cross 2. Short-eared female X lop-eared male 18 



Cross 3. Belgian hare female X lop-eared male ... 20 



Cross 4. Lop-eared female X half-blood lop male 21 



Cross 5. Half-blood lop female X lop male 179 22 



Cross 6. Half-blood lops mated inter se 23 



Other matings of half-blood lops and additional Cross 6 matings 26 



Matings of three-quarter-blood lops 3 1 



Cross 7. Quarter-blood lop female X short-eared male 33 



Cross 8. Quarter-blood lop X three-quarter-blood lop 34 



Limitations of the data studied 34 



Conclusions 35 



PART II. WEIGHT 37-40 



PART III. SKELETAL DIMENSIONS 4i-44 



PART IV. COLOR 45-8 



Color variation in relation to color factors 45 



Development of the factor hypothesis 46 



The general color factor, C 46 



The specific pigment factors, B, Br, and Y 46 



The intensity factor, I or D 46 



The factor for a pigment pattern of the individual hair, A 47 



The factor for uniformity of pigmentation, U, or spotting with white, S . 47 

 The factor for extended distribution of black or brown, E, alternative with R 



(restricted distribution) 47 



Interrelations of factors E and U 48 



Interrelations of factors B, Br, and Y 49 



Gametic structure and variation 49 



Gametic and zygotic formulce 5 



Color varieties of the rabbit 5 1 



Gray type 5 2 



Black type 



Yellow type 53 



White type 



Zygotic variation within each color variety 54 



Gray 54 



Blue-gray 60 



Black 61 



Blue 62 



Yellow 63 



Sooty 64 



White 65 



The material basis of heredity factors 68 



BIBLIOGRAPHY 69 



DESCRIPTION OF PLATES 7 



3 



