in the wild moth, Abraxas 78-80 h. Multiple allelomorphs 81-84 in the wild Grouse Locust 81-83 in domesticated mice and rabbits 83 in Drosophila ampelophila 84 4. MUTATION AND EVOLUTION 84-88 CHAPTER III THE FACTORIAL THEORY OF HEREDITY AND THE COMPOSITION OF THE GERM PLASM 1. THE CELLULAR BASIS OF ORGANIC EVOLUTION AND HEREDITY 89-98 2. THE MECHANISM OF MENDELIAN HEREDITY DISCOVERED IN THE BEHAVIOR OF THE CHROMOSOMES 98-102 3. THE FOUR GREAT LINKAGE GROUPS OF DROSOPHILA AMPELOPHILA 103-118 a. Group I. 104-109 b. Group II. 109-112 c. Group III. 112-115 d. Group IV. 115-118 4. LOCALIZATION OF FACTORS IN THE CHROMOSOMES 118-142 a. The Evidence from Sex Linked Inheritance 118-137 b. The Evidence from Interference 137-138 c. The Evidence from Non-Disjunction 139-142 5. HOW MANY GENETIC FACTORS ARE THERE IN THE GERM-PLASM OF A SINGLE INDIVIDUAL? 142-143 6. CONCLUSIONS 144 CHAPTER IV SELECTION AND EVOLUTION 1. THE THEORY OF NATURAL SELECTION 145-161 2. HOW HAS SELECTION IN DOMESTICATED ANIMALS AND PLANTS BROUGHT ABOUT ITS RESULTS? 161-165 3. ARE FACTORS CHANGED THROUGH SELECTION? 165-187 4. HOW DOES NATURAL SELECTION INFLUENCE THE COURSE OF EVOLUTION? 187-193 5. CONCLUSIONS 193-194 INDEX 195-197 * * * * * CHAPTER I A REVALUATION OF THE EVIDENCE ON WHICH THE THEORY OF EVOLUTION WAS BASED We use the word evolution in many ways--to include many different kinds of changes. There is hardly any other scientific term that is used so carelessly--to imply so much, to mean so little. THREE KINDS OF EVOLUTION