142 HEREDITY AND EUGENICS 



characteristic for over 2,000 3'ears, is believed by 

 Salaman (191 1) to show in marriages with Gentiles 

 incomplete or variable dominance and segregation. 

 Thus, from such marriages 328 children were classed 

 as Gentile in facial expression, twenty-six as Jew, 

 and eight intermediate. The subject is one which 

 invites more detailed study. Salaman points out 

 two other inherited peculiarities of the Jewish race: 

 (i) Amaurotic* family idioc}-, a disease whose victims 

 die in earl}^ childhood, and which is known onty in 

 Jews; (2) absence of alcoholism. 



As our knowledge of the physiological controls of 

 development in the human individual increases, a 

 deeper anatysis of man}^ physical characters will 

 become possible. Various abnormalities in man, 

 such as brittle bones and blue sclerotics,t are already 

 believed to be due to an hereditary inferiority of 

 mesenchyme. J And the glands of internal secretion, 

 such as the pituitary, pineal, and thyroid, are alread}^ 

 known to control growth and to produce, by their 

 presence in excess or defect, various characteristic 

 conditions of the features or the limbs. Inherited 

 differences in these glands ma}' thus account for a 

 whole series of changes, not only in physical con- 

 formation, but in temperament as well.§ 



What is often referred to as a remarkable feature 

 of human inheritance, which is observed also and 

 made use of in horse and cattle breeding (Hover, 

 1 91 6), is the occurrence of '' prepotency." Although 



* Amaurosis is blindness without apparent lesion of the eye, 

 resulting from disease of the optic nerve, retina, brain, or spine. 



J The hard, white, fibrous membrane forming the outer coat 

 of the eyeball, except at the front where it is replaced by the 

 cornea. 



i The embryonic connective tissue, which forms not only 

 connective tissue, but also the bloodvessels and lymphatics. 



§ This subject will be referred to again more fully later (see 

 pp. 210, 219). 



