I40 HEREDITY AND EUGENICS 



were taken from the upper classes. Goring studied 

 British convicts, and also found a correlation of o-; 

 for parent and offspring, but none for husband and 

 wife. 



Wright and Lewis (1921) have made experiments 

 on guinea-pigs, in which they found marked differences 

 in resistance to tuberculosis in a number of inbred 

 families . The high resistance of one family was trans- 

 mitted b}^ either sex to the offspring in crosses with 

 other inbred families. It is found that the factors 

 determining resistance to tubercle are not closely 

 related to the other elements of vigour, such as growth- 

 ratio, adult weight, frequency and size of litter, per- 

 centage of 3'oung born alive, and percentage of young 

 raised to weaning. Inbreeding brings out differences 

 between families in these characters, as well as 

 independently in resistance to tuberculosis. 



Nothing very definite appears to be known re- 

 garding the relation of cancer to inheritance in man. 

 In animals, however, many definite facts have been 

 determined. These are referred to by L. Loeb (192 1). 

 The inheritance of specific kinds of cancer in rats 

 and mice and other animals is known — e.g., cancer of 

 the inner canthus* of the eye in cattle, cancer of 

 the scrotum in rats, and sarcoma of the thyroid 

 in rats. Miss Slve has shown the inheritance of 

 cancer of the liver and other special forms of cancer 

 in certain families of mice. I am informed that the 

 late Professor Plummer recorded cancer in three 

 generations of wolves in the Zoological Gardens, oc- 

 curring always in the same place — viz., the shoulder. 

 In the fruit fly, Drosophila, Stark found two kinds 

 of inheritable tumour-like formations originating by 

 mutation. Others have since been found. Since 

 they cause death they are classed as lethal mutations. 

 Loeb concludes that the endemic occurrence of cancer 



* 



The angle next the nose where the eyelids meet. 



