204 HEREDITY AND ENVIRONMENT 



ing after an injury, which is due to a defi- 

 ciency in the clotting power of the blood, is 

 strongly inherited in the male line in certain 

 families. Fecundity and a tendency to bear 

 twins or triplets, left-handedness, a peculiar 

 lack of resistance to certain diseases, and many 

 other physiological peculiarities are probably 

 inherited. 



(d) Psychological characters appear to be 

 inherited in the same way that anatomical and 

 physiological traits are; indeed all that has 

 been said regarding the correlation of morpho- 

 logical and physiological characters applies 

 also to psychological ones. No one doubts 

 that particular instincts, aptitudes and ca- 

 pacities are inherited among both animals and 

 men, nor that different races and species differ 

 hereditarily in psychological characteristics. 



Certain breeds of dogs such as the mastiff, 

 the bull dog, the terrier, the collie and many 

 others are characterized by peculiarities of 

 temperament, affection, intelligence and dis- 

 position. No one who has much studied the 

 subject can doubt that different human races 

 and families show characteristic differences in 



