No. 528] SKIN PIGMENTATION IN MAN 



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what is needed in these studies is not so much a vaster 

 number of families as more families that have been com- 

 pletely and accurately studied. Human pedigrees, like 

 breeding records, are full of imperfect statements. The 

 whole truth is to be gained only by visiting the families 

 and carefully cross questioning them. 



VII. Conclusions 

 What conclusions can be drawn from a study of the 

 foregoing study of albinos? 



1. Two albinic parents have only albinic offspring. 

 This holds for the families Nos. 1-3, comprising four 

 children altogether. These cases were all given us by Mr. 

 R. R., an intelligent and reliable albino. He married an 

 albino and had one son still, or until recently, living ; al- 

 binic like his parents. These cases are, so far as I know, 

 the first that have been published. 



Dr. R. A. Gortner tells us that he formerly knew 

 of a family of two albino parents and five albino chil- 

 dren near his home in Nebraska, but attempts to trace 

 this family have proved unsuccessful. The probability 

 that this rule will hold generally is enhanced from ex- 

 periments on animals where two albinos always yield 

 only albino offspring. 



2. Even when neither parent of albinos is an albino 

 they are apt to be related. In 33 such families 11 are al- 

 most certainly from consanguineous matings. This is 

 33 per cent., a proportion that is certainly vastly greater 

 than that of the population at large. 27 The fact that 

 consanguinity even when present must frequently be 

 unknown heightens the probability that parents of al- 

 binos are usually related. The importance of this con- 

 clusion is that it tends to bring these cases under the 

 general rule that a recessive condition appears only 

 when both parents carry the same defect; and the prob- 

 ability that both carry the same defect is heightened 

 when both belong to the same strain. 



21 Lagleyze (1907) finds in 48 families of albinos consanguinity in 10, with 



