274 GENETICS AND EUGENICS 



port in his studies of skin-color and hair-form inheritance 

 in negro-white crosses, which supports the idea that mul- 

 tiple factors are involved, or one or more chief factors as- 

 sociated with modifying factors. The well known lack of 

 correlation between skin-color and hair-form in mulattoes of 

 the F2 or later generations certainly indicates the existence 

 of independent factors affecting these characters. 



As regards shape of the head, anthropologists have long 

 distinguished between long-headed and round-headed races 

 or types within mixed races. These may be convenient terms 

 for purposes of classification, but it by no means follows that 

 the t}^es are alternative in heredity. Without positive evi- 

 dence to the contrary, it is safe to assume from what we know 

 of skull shape in animals and in negro-white crosses that 

 skull shape is in all cases blending (multiple factorial) in in- 

 heritance. Salaman (1911) himself an English Jew, has de- 

 scribed the Jewish tj^^e of countenance as recessive to the 

 Anglo-Saxon type in mixed marriages in England on classi- 

 fications of the offspring as of Jewish or Gentile type, made 

 for him by Jews, but the evidence is far from satisfactory and 

 not based on any clearly defined differences. If measurable 

 characters were considered, it is probable the inheritance 

 would be found to be blending, and the classification adopted 

 in his tables to have been based on blending in many char- 

 acters rather than on simple segregation in any one. 



It is to be noted that in man, as in wild species of animals 

 and plants, characters which hlend in heredity are in no case 

 abnormal or monstrous conditions, but are such as distin- 

 guish one member of a perfectly normal population from 

 another. 



The case is very different when we come to the category of 

 simple Mendelian characters, whether or not sex-linked. 

 Here a great majority of the characters listed refer to abnor- 

 malities or monstrosities. As regards variation in the color of 

 hair, skin and eyes, we have, in these, recessive or loss varia- 

 tions, similar to those of other mammals, producing a graded 

 series of probable allelomorphs ranging from black to albino. 



