468 



THE AMERICAN NATURALIST [Vol. XLV 



heritance as the Davenports suggest) appear to be in- 

 volved, i. e., a tyrosin-producing factor and a tyrosinase- 

 producing factor, one at least a function of the epidermal 

 cell, and both having as likely a chromosomal representa- 

 tive (a "teleomorph" — Spillman) as any other cell organ 

 or function. The tyrosin-producing factor is probably 

 generally absent in albinos, locally appearing abnormally 

 in tumor cells, hence two albinos can never produce col- 

 ored offspring, as amply shown by the results of the 

 experimental breeders. 



The observations of Stedman, reported by Bateson 

 (p. 227) "to the effect that an albino negress married to 

 a European had children all mulattos" does not neces- 

 sarily imply that the factor determining the blackness 

 of the negro (tyrosin production) was carried by the 

 albino. Mulattos are frequently so classified on the 

 basis of marks other than color of skin. Many mulattos 

 are no darker than many white brunets. In the above 

 case the factor controlling tyrosin production may very 

 well have been contributed by the father alone. This 

 instance does not necessarily controvert the assumption 

 that albinos lack the factor of tyrosin production. 



Moreover, crosses between albinos and pigmented in- 

 dividuals result in families where albinism greatly pre- 

 ponderates, as shown in the recent "dissertation" by 

 Stainer. In crosses between whites and blacks one deals 

 apparently more especially with the factors of great and 

 small capacity for tyrosin production— tyrosinase being 

 probably of more general distribution. Judging from 

 the pedigrees published by Stainer, absence of capacity 

 for tyrosin production (albinism) in man behaves more 

 like a dominant character (or at any rate, not like a pure 

 recessive) to the presence of such capacity. This is not 

 in accord with the results of the Davenports, which seem 

 to indicate that "internal conditions that lead to deeper 

 pigmentation dominate over the weaker conditions"; 

 similarly as regards color of hair and eyes, "the more 

 pigmented condition tends to be dominant over the less 

 pigmented" according to the earlier investigations of 

 Holmes and Loomis as well as the more recent work of 

 the Davenports. Nor does it accord with the results of 



