I20 HEREDITY AND EUGENICS 



sounds, and cites a famil}^ in which all the colour-blind 

 members were also stone-deaf. He also describes an 

 interesting famity, here thrown into pedigree form 

 (Fig. 25), having coloboma iridis or cleft iris. This 

 pedigree is difficult to explain, for it not only shows 

 transmission, as in an ordinary male sex-linked 

 character, through an unaffected mother to half her 

 sons, but also direct transmission from father to son in 

 two cases, unless the waves here happened to be trans- 

 mitters. One son (III. 7) only had the defect in one 

 eye. vSedgwick also describes cases of inheritance 

 of aniridia (absence of iris), amaurosis (blindness), 

 microphthalmia, absence of eyes, and squinting. 

 The latter is due to defective musculature of the 



I Ox 



i^ 



nx6^ ¥ 



n DxO bao 



Fig. 25. — Family showing Cleft Iris. 



eye, and is stated to be hereditary in some families 

 for many generations. In one family the five boys 

 squinted in the left eye or in both eyes, while the five 

 girls were normal. Their father and mother were 

 normal, but the mother's sister had a boy and girl 

 both squinting with the left eye. 



A celebrated case which is often referred to in the 

 early literature is that of " the porcupine man," 

 Edw^ard Lambert. The first account appears to be 

 that of Machin (1733). A countr}^ labourer showed 

 his son, who was then fourteen, in London. The son 

 had a very scaly skin which did not bleed when cut, 

 but was callous and insensible. The skin was shed 

 every year in the autumn, a new skin growing up 



