TABLE OF CONTENTS ix 



Sex and Sex Reversal in Frogs 256 

 Transformation of Bidder's Organ of the Male Toad 



into an Ovary 266 



Sex Reversal in Miastor 269 



Sex Reversal in Birds 271 



The Effect of Ovariotomy in Birds 272 



The Sex of Parabiotic Salamander Twins 275 



Sex Reversal in Hemp 276 



XVIII. Stability of the Gene 281 



XIX. General Conclusions 300 



The Effects Produced by a Change in Chromosome 



Number and by a Change in a Gene 300 



Is the Mutation Process Due to a Degradation of the 



Gene ? 307 



Are Genes of the Order of Organic Molecules? 309 



Bibliography 311 



Index 337 



