CONTENTS 15 



CHAPTER PAGE 



A. THE METHODS OF HUMAN GENETICS— contd. 



3. Autosomal recessives 329 



4. Sex-linked genes 331 



5. Continuous variation 333 



6. The genetic analysis of a continuously varying character: 



intelligence 335 



B. THE GENETIC STRUCTURE OF HUMAN 



POPULATIONS 



1. Race 340 



2. Gene differences between races. 342 



3. Nations and races 343 



4. Race crossing 346 



5. Genetic differences between classes 347 



6. Changes in population composition 350 



7. The control of the genetic composition of human populations 354 



PART FIVE 



THE NATURE OF THE GENE 



XVI. The Nature of the Gene 361 



A. CYTOLOGICAL CONSIDERATIONS 



1. Chromosome movements 361 



2. SpiraUzation of chromosomes 364 



3. The connections of chromomeres 367 



B. DEVELOPMENTAL CONSIDERATIONS 368 



C. GENERAL GENETICAL CONSIDERATIONS 



1. Step allelomorphism 369 



2. Mutable genes 372 



3. Position effects 373 



4. The size of the gene 377 



