xviii LIST OF ILLUSTRATIONS 



FIG. PAGE 



137a. Swarming gametes of Ectocarpus 246 



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

 phila 252 



139. Superfemale and supenuale of Drosophila 253 



140. Normal male and female and two mosaics of gypsy moth . . 255 



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



a free martin 258 



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

 chus 262 



143. Larva of Perla and ovotestis of same 267 



144. Chromosome groups of spermatogonia and oogonia, and 

 diploid male egg of Perla 268 



145. Chromosome groups of frog 272 



146. Hermaphroditic condition in frog 275 



147. Bidder's org'ans of toad 277 



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

 ovaries 278 



149. Female and male hemp plants 288 



150. Four pure lines and general population of Princess bean . . 295 

 15L Types of hooded rat 297 



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

 phila 302 



153. Distribution of pigment cells in different color types of 

 pupae of cabbage butterfly 304 



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

 butterfly after exposure to different colored lights .... 306 



155. Guinea pigs with alcoholic ancestry 307 



156. Young rat with hemorrhagic areas after exjDOsure of mother 



to radium . 309 



