PROVISIONAL PROPOSITIONS 291 



quite normal individuals, e.g. cousins, each having albinism 

 latent or recessive in the germ-plasm, may result in one or more 

 of the offspring being albinos (Medical Chronicle, 1911, p. 75). 



(c) In a third group the disease finds expression in one sex only 

 (the males), but may be transmitted by the apparently unaffected 

 other sex. Thus haemophilia a chronic liability to excessive 

 bleeding is almost always, if not (according to Bulloch and 

 Fildes) always, confined to males. It is partly associated with 

 weakness in the walls of the blood-vessels, and partly with a lack 

 of coagulating power in the blood. The disease passes from an 

 affected father through an unaffected daughter to a grandson. 

 For some unknown physiological reason it does not find expres- 

 sion in the female sex, unless, perhaps, in some disguised form. 



Colour-blindness or Daltonism has been recorded (Horner) through 

 the males only of seven generations, and it is usually confined to 

 males. Dejerine cites a pedigree (fide Appenzeller) in which all the 

 males had a kind of cataract through four generations. Mott men- 

 tions as other cases of abnormal conditions generally restricted to 

 the males, " pseudo-hypertrophic paralysis " and " hereditary optic 

 neuritis or optic atrophy." 



Edward Lambert, born in 1717, is said to have been covered with 

 " spines." His six children showed the same peculiarity, which 

 began to be manifest from the sixth to the ninth month after birth. 

 One of his children grew up and handed on the peculiarity to another 

 generation. Indeed, it is said to have persisted for five generations, 

 and in the males only, unilateral transmission. (See Phil. Trans. 

 1755 ; Prichard, History of Mankind, 1851.) 



2. The Expression of Disease-inheritance may change 

 from Generation to Generation, " Diseased organisms are apt 

 to breed disease, but not always, though sometimes, their own 

 disease." This cautious statement seems to be well borne out 

 by the facts. 



Hannot (Arch. gen. de Medecine, 1895) gives the following 

 illustrations. A typical gouty subject, with his joints hampered 

 by accumulations of urates, may beget a son as gouty as himself, 



