342 THE AMEBIC AN NATURALIST [Vol. XLII 



continue to roll up outside, given especially its flattened 

 shape ; it rolls up into a spiral the plane of which, at the 

 beginning, is perpendicular to the surface of the skin" 

 (Deniker '06, p. 43). As all gradations exist between 

 straight hair and wool in other characters, so probably in 

 the initial curvature. The intermediate nature of ivavi- 

 ness is probably due to an intermediate degree of curva- 

 ture beneath the skin. This curvature of the follicle, 

 again, is a departure from the usual mammalian condi- 

 tion and is in the line of differentiation or advance. 



We are now in a position to formulate our problem. 

 How do the more specialized types of hair form— much 

 flattened and much curved woolly hair and slightly flat- 

 tened, slightly curved wavy hair behave in heredity 

 toward each other and toward the nearly cylindrical 

 straight hair? 



The data for this study are derived from the same 

 sources as those of our eye color study 1 and include the 

 ancestral characteristics of about 500 children for two 

 ascending generations. About 230 families are involved. 



The nomenclature of hair form that collaborators were 

 requested to employ was as follows: Straight, wavy, 

 curly, kinky. As our cards were distributed only among 

 whites the term 1 'woolly " was not used. The terms seem 

 to have been, for the most part, understood by the 

 collaborators. 



The first result revealed by an analysis of the pedigree 

 data regarding hair form is that straight hair is recessive 

 to the curved types. Thus to 70 pairs of parents both said 

 to have straight hair were born 185 children of which we 

 have records. Of these 167 are recorded as having 

 straight hair; 13 1 'wavy" and 5 1 'curly." Also 164 

 grandparents, both with 1 1 straight hair, ' ' are said to have 

 had 146 straight-haired children, 11 "wavy" and 7 

 " curly." Knowing how liable to slip collaborators are 

 we venture to affirm that probably not less than 98 per 

 cent, of the offspring of straight-haired parents have 



1 Science, N. S., XXVI, No. 670, pp. 589-592, November 1, 1907. 



