xvi LIST OF ILLUSTRATIONS 



FIG. PAGE 



138. Sex formulae of diploid, triploid, tetraploid types of Droso- 

 phila 241 



139. Superfemale and supermale of Drosophila 242 



140. Normal male and female and two mosaics of gypsy moth . 244 



141. Union of chorions of two foetal calves, one of which becomes 



a free-martin 247 



142. Normal male, normal female, and parasitized male of Inar- 

 chus 251 



143. Larva of Perla and ovotestis of same 256 



144. Chromosome groups of spermatogonia and oogonia, and 

 diploid male egg of Perla 257 



145. Chromosome groups of frog 261 



146. Hermaphroditic condition in frog 264 



147. Bidder's organs of toad 266 



148. Transformation of Bidder's organs, after castration, into 

 ovaries 267 



149. Female and male hemp plants 277 



150. Four pure lines and general population of Princess bean . 284 



151. Types of hooded rat 286 



152. Normal and mutant types of abnormal abdomen of Droso- 

 phila 291 



153. Distribution of pigment cells in different color types of 

 pupae of cabbage butterfly 293 



154. Diagram of percentages of color types of pupae of cabbage 

 butterfly after exposure to different colored lights . . . 295 



155. Guinea pigs with alcoholic ancestry 296 



156. Young mice with hemorrhagic areas after exposure of mother 



to radium 298 



