CONTENTS xiii 



CHAPTER VIII 



PAGE 



Coupling : complete and partial Reversion on crossing : 

 latent characters Examples in peas, mice, and 

 sweet-peas Various Mendelian characters Doubt- 

 ful cases ; normal fertilization The supposed 

 ' swamping ' of new species on crossing with the old 

 Summary of Mendelian ideas Mendelism and 

 biometry : researches of Yule and Pearson Practical 

 applications : Biffen's work with cereals ; ' strength ' 

 of wheat-flour and rust-immunity - 185 



CHAPTER IX 

 RECENT CYTOLOGY 



The cell Cell-division and cell-fusion The nucleus 

 Nuclear division The nature and properties of 

 chromosomes The reducing division The study of 

 the chromosomes in the light of Mendel's discovery 

 Chromomeres The heredity of sex The germ- 

 plasm theory - - 222 



CHAPTER X 

 CONCLUDING CHAPTER 



The science of genetics Mendel's law The ^-generation 

 and the 2^-generation Discontinuous variation 

 The mutation theory Continuous variations Gene- 

 tic variations and acquired variations Johannsen's 

 theory of the pure line The modern view of the 

 method of origin of new species The science of 

 genetics applied to human affairs George Bernard 

 Shaw's view of the situation ... 264 



