220 Variotcs Human Diseases [cn. 



afifection of all the family of the first case is in any way 

 connected with the sudden appearance of the condition 

 cannot of course be said. 



The other conditions which Gossage finds to be domi- 

 nants as a rule are : 



Epidermolysis bullosa : in which the skin is liable to 

 blister for trifling causes. 



Xanthoma : the presence of yellow patches on the skin. 



Multiple Teleangiectasis : small naevus-like spots. 



Hypotrichosis congenita familiaris : the loss of hair at 

 or soon after birth. 



Monilithrix : a nodose condition of the hair. 



Porokeratosis : a curious disease in which a raised horny 

 ridge appears on the skin, spreading centrifugally, leaving 

 behind it a patch in which the constituents of the skin 

 undergo partial atrophy. 



The spontaneous origin of porokeratosis has several 

 times been observed. In epidermolysis transmission through 

 unaffected persons occurred in some of the strains but was 

 exceptional. 



Besides these skin-diseases Gossage suggests that en- 

 larged spleen is generally transmitted as a dominant. 

 There are also four pedigrees showing the same pheno- 

 menon in the case of the condition called diabetes insipidus 

 or polyuria. 



To these may be added with some probability certain 

 forms of inherited oedema and some of the kinds of hare- 



The most extensive pedigree that has yet been compiled 

 for any disease in man is that for congenital stationary 

 night-blindness, of which the first part was published by 

 Cunier in 1838*. Working on this foundation Nettleship 

 succeeded in obtaining material for a most elaborate 

 genealogy including 21 16 persons (Fig. 31). The aftection 

 consists in a marked inability to see in a dim light. In this 

 family the transmission is through the affected, and no 



* Annates Soc. Med. de Gand^ 1838, p. 383. [Not seen : quoted from 

 Nettleship.] 



