Paleontology 24-27 Papilio polytes 63 Papilio turnus 63 Paramecium 181, 182 Paratettix 81 Peach eye color 114 Pea comb 54 Pearl 161 Peas 47 Pigeons 172, 174, 175 Pink eye color 114, 115 Planarian 22 Plymouth Rock 77 Podarke 22 Polar bodies 126 Pole arms 5 Protozoa 181 Pseudo-parthenogenesis 183 Purple eye color 109 Purpose 4 Rabbits 83, 170 Rats 176-180 Reduction division 182 Reproductive cells 96 Ruby eye color 106 Rudimentary organ 116 Rudimentary wing 70, 71, 107 Sable body color 107 Science definition of 6 Segregation 41 Selenka 94 Sepia eye color 13, 114 Sex chromosomes 118 Sex linked inheritance 75, 118-130 Sexual dimorphism 62 Sheep 33 Single comb 54 Sooty body color 50, 114, 115 Speck 68, 69, 111 Spencer 145 Spermatozoön 91, 98 Stars, evolution of 6 St. Hilaire 27-30 Strap wing 110, 111 Stumpy wing 11 Sturtevant 76, 143 Stylonychia 183 Survival of the fittest 146 Systematist 85 Tails 33 Tan flies 106, 107 Tetrabelodon 191 Trefoil 111 Truncate wing 111, 112, 167, 168 Unfolding principle 34 Unio 22 Unit character 74, 75 Use 31 Variation discontinuous 13 Vermilion eye color 108, 163 Vestigial wing 11, 55, 56, 109, 133 Vital force 34 Wallace 36 Walnut comb 54 Weismann 17, 31-33 Wilson, E. B. 125 Wingless 67 Winiwarter 126 White eye color 13, 75, 119-130 Whiting eye color 163, 164 Woodruff 183 Yellow body color 108, 133 Yolk sac 16, 17 Zeleny 169 * * * * * Corrections made to printed original. page 104, "shown in figures 53, 54, 55, 56": '52, 53, 54, 55' in original.