vi CONTENTS. 



CHAPTER III. 

 CORRELATED VARIATIONS. 



The measurement of correlation Galton's function Cor- 

 relation between various organs in man, in local races of 

 the shrimp, and in crabs Comparison between primitive 

 and civilised races of man Correlation between morpho- 

 logical characters and the reproductive system Genetic 

 Selection in man Especial fertility of type forms in cer- 

 tain plants Evolution in the Peppered moth Parallel 

 variation Importance of mathematical treatment of varia- 

 tion, 72 



PART II. 

 THE CAUSES OF VARIATION. 



CHAPTER IV. 

 BLASTOGENIC VARIATIONS. 



The ultimate cause of blastogenic variation Effect of stale- 

 ness and of comparative maturity of sex-cells on the 

 characters of organisms Amphimixis Identical twins 

 Transplantation of ova in the rabbit Law of Ancestral 

 Heredity in man and in the Basset hound Regression 

 towards mediocrity Exclusive inheritance Homotyposis, 101 



CHAPTER V. 

 BLASTOGENIC VARIATIONS (Continued). 



Reversion; commonest in crossed races, as of the pigeon and 

 fowl; its theoretical explanation Prepotency; in the 

 trotting horse and in man; probably due in large part to 

 inbreedingMendel's Law of Hybridisation, and its 

 range Natural and artificial plant hybrids Animal 

 hybrids Sports ; probably of different origin to normal 

 variations Artificial production of monsters Telegony; 

 probably non-existent Parthenogenesis in an Ostracod 

 and in Daphnia Does sexual reproduction induce vari- 

 ability? Relation of variability of individual to variability 

 of race Asexual reproduction in plants Bud-variation, 138 



