Mendelism and Mutation 



CONTENTS xm 



CHAPTER XV 



Pi 



Mendelism— A typical case of Mendelian inheritance The cytological 

 basis of Mendelism— Mutation— Mutations accompanied by cl 

 in chromosome number— Bearing on the origin of species and varieties 

 Mutations accompanied by no change in chromosome number < lonclusion. 



:;.-, ! 



CHAPTER XVI 



Sex 



Experimental evidence for sex-determination — Sex-chromosomes Sex- 

 chromosomes and Mendelism— Experiment :il alteration of the Bex ratio- 

 Metabolic theories of sex — General discussion. 



CHAPTER XVII 



Linkage 



A typical case of linkage— Sex-linkage— Non-disjunction— Linkage groups 

 The chiasmatype theory— Application of the chiasmatype theory to the 

 problem of linkage — General discussion— Other theories of linkage Value 

 of chromosome theory of heredity. 



CHAPTER XVIII 



Weismannism and Other Theories 



Darwin's hypothesis of pangenesis — DeVries's theory of intracellular 

 pangenesis — Nageli's idioplasm theory — Weismann's theory -Some modern 

 aspects of Weismannism — Non-factorial theories — A chemical theory of 

 heredity — Conclusion — Bibliography 14 (for Chapters XTV-XVIII). 



Index . . . 427 



