INHERITANCE OF TRAITS ASSOCIATED WITH SKIN COLOR. 39 



rarely occur in these hybrids except in extreme youth (5 years or 

 under). Red hair may be carried by dark brown-haired parents, and 

 reappears in their children, especially when young, but often becomes 

 later covered over by brown pigment. It is pretty clear that the fac- 

 tors involved in hair pigmentation are so numerous that their analysis 

 will yield only to a careful, quantitative study. 



III. Hair Form. 



The forms of the head hair constitute a series that is apparently 

 continuous. Anthropologists, however, recognize only five varieties: 

 straight, wavy, curly, frizzy, and woolly (Topinard, 1894, p. 35; Den- 

 icker, 1906, p. 38). These types differ not only in general curvature 

 but also in cross-section, for the head hair is elliptical on cross-section 

 and the ratio of the long to the short axis is said to be as 100 to 85 in 

 straight-haired races like the North American Indian, and as 100 to 

 34 in Papuans, 100 to 50 in Hottentots, 100 to 60 in negroes. There 

 seems to be a rather close connection between the degree of flatten- 

 ing of the hair and the degree of its curvature, and anthropologists 

 commonly ascribe the curving to the flattening. The terms relating 

 to general hair form have been defined as follows by Waldeyer (1884, 



P- 51)- 



Straight hair is characterized by the absence of any wavy or spiral curva- 

 ture. Wavy hair shows wave-like curves in one plane or in a slightly twisted 

 surface, the distance from convexity to convexity being great — usually several 

 centimeters. Curly hair is spirally curved, especially at its free ends. It is 

 to be noted that curly hair when cut close no longer reveals its true character. 

 Frizzled hair has a close curl even from the base. Woolly hair, as used com- 

 monly in speaking of people, is closely, spirally curled hair which does not 

 grow to the length of more than 2 or 3 cm. and is apt to form tufts (Topinard, 

 i894,p.35i; Waldeyer, 1884, pp. 5 1-53).* But between these typical conditions 

 all transitions occur. 



Table 32. — Hair form in negro X white crosses. 

 (A) STRAIGHT X STRAIGHT. 



* At the Good Samaritan Hospital (colored) at Columbia, South Carolina, I got hair 

 from a negro (skin about N 65 per cent) which formed a spiral of about 4 mm. diameter. 

 The average thickness of the hair mat on the man's head was not over 5 mm. The man 

 stated he had his hair cut about once in four months; but since colored persons take a pride 

 in and boast of rapidly growing hair, it is probable that even this represents a minimum 

 interval. 



