132 HEREDITY IN RELATION TO EUGENICS 



ubiquitous. Abrasions and the openings of the sebaceous 

 glands and the hair folhcles offer vulnerable points. The 

 main reliance of the organism must be its internal means of 

 defense. The efficiency of specific means of resistance is 

 undoubtedly an inherited quality. We find families charac- 

 terized by low resistance to specific germs of particular dis- 

 eases. 



Thus liability to boils and eczema appears as a family 

 trait in the Dow-1 family. One of the parents is subject 

 to boils and the other to eczema. Of five children three are 

 subject to eczema and one to boils. It seems probable that 

 we are here dealing with a lack of resistance to infection 

 through the skin in both parents, leading to a non-resistance 

 in all of the children. A few cases of inheritance of more 

 specific types of skin diseases are cited below. 



a. Congenital Traumatic Pemphigus (epidermolysis bul- 

 losa). — The children are born with a liability to form 

 fluid filled vesicles after the smallest physical provocation. 

 The excessive vulnerability shows itself in the first month 

 of life and is said to diminish from 40 to 50 years of age and 

 to cease altogether in old age. It is strongly hereditary, 

 often through several generations (5 in Bonajuti's case); 

 it shows also a prevalence in particular families and is rather 

 more frequent in males than females. The sHghtest injury, 

 blow, pressure, friction or scratching is followed by the 

 formation of a bulla. The bullae are often full of blood and 

 of large size, 5 centimeters or more across and their shape 

 may be irregular instead of round or oval depending upon 

 the nature of the injury. Fingers and nails are often de- 

 formed or altogether destroyed. The pathology of the dis- 

 ease is obscure; it seems to be influenced by arsenic (Rad- 

 cliffe-Crocker, 1903, p. 293). 



The case described by Bonajuti is given in Fig. 105. Of 

 an affected parent about half the offspring are affected. Two 



