PHYSICAL CHARACTERS IN MAN 57 



descendants, but Katherine (abnormal) also had only 

 normal descendants through three generations. If 

 the character were recessive its absence here would 

 be explained, since her husband was probably homo- 

 zygous normal. Maria and Salome, if their husbands 

 (Bollenbach) were heterozygous, should have half 

 their children of each type. The actual numbers were 

 three normals to four hairless and seven normals to 

 seven hairless respectively. The numbers are, of 

 course, too small to make a certain interpretation, 

 but the most likely interpretation appears to be that 

 the character behaved as a recessive. In the case of 

 Katherine, it is very unlikely that it would fail to 

 appear in any of her four children if it were dominant. 

 The fact that the sex of so many of the children 

 is unrecorded indicates that the records are not, 

 perhaps, very accurate. 



Inbreeding does not explain the origin of this 

 character, which was probably due to germinal change, 

 and if the Bollenbachs were homozve^ous it would 

 behave partly as a dominant. The abnormal section 

 of the family is fast dying out. Sexual selection is 

 apparently a factor, for abnormal members of the 

 family often remain single. Of the fourteen children 

 of Salome, all died but one (Daniel), who had two 

 children, only one of which reached maturity. Michel 

 remained childless. Only two abnormal members of 

 this famil}^ remain — both old men. At their death, 

 the abnormality will be lost after fifteen abnormal 

 individuals had appeared in three generations. This 

 is a marked case of an abnormality appearing sud- 

 denly and then disappearing in a few generations. 



Albinism 

 The monograph on albinism in man, by Pearson, 

 Nettleship, and Usher (1911-1913) is a very elaborate 

 and detailed treatment, which will serve as a basis 



