158 HEREDITY IN RELATION TO EUGENICS 





Fia. 134.— Pedigree of hemophilia in the Mampel family, originally of 

 Kirchheim near Heidelberg, Germany. Black symbols indicate bleeders; 

 it is seen that they are males only, but they, in turn, have no bleeding sons. 



34. Disease of the Thyroid Gland 



This may lead to a variety of effects, cretinism, goitre, 

 mjocedema, exophthalmic goitre, etc. Many of these show 

 evidence of an inheritance of the liability to thyroid de- 

 generacy. 



a. Cretinism. — This is characterized by arrest of growth, 

 by large pendulous abdomen, poor teeth, coarse, scanty 

 scalp hair, mongolian face, feebly developed genitalia, and 

 marked impairment of intelligence. The thyroid gland is 

 often absent and a goitre frequently present. The distri- 

 bution of the disease is interesting. It appears chiefly in 

 mountainous countries where close intermarriage is more 

 likely to occur than on the plains. Thus it abounds in Swit- 

 zerland and is said to occur in some parts of Scotland. It is 

 a cause of deportation when it occurs in immigrants to this 

 country. That it is hereditary admits of no doubt. Aosta, 

 at the southern base of Mount St. Bernard, was once a great 

 breeding place of cretins, since their marriage there was per- 

 mitted. For some years they have been segregated and kept 

 from marrying and now, we are told, they are nearly all 

 gone (Jordan, 1910). 



b. Goitre. — That goitre frequently occurs repeatedly in 

 families is well known; but in how far this is due to common 

 sources of infection is still disputed. Buschan states that 



