HAIR AND WOOL 781 Figure 9. Ian Clunies Ross .... 'NEGRO . .. •.•..?•:•.:r.,-..-:-p..-•.•..:. ' •' • .•" :'.•.. .. :•.• . •:. -:•.,_:.. :-•, ,:.: ...... •.•,....-.. . --. .,• ::• ':: .:? . . '.',:':., •½-. ..•.:.•,•:. '%•' . ..• '"?{•'.•'?•.' . ?:'- '•:':'" .•,..• .•.?.."• ...... ..... :.. . •:'•.•:•. •,:•.•: . .:• :•",.• •? •:':'•'•"•--•::.,. : ,,•. •:' : ----.. , •,:?•:.,½.:-2.. .:•: "':.. .... :•'.. '•,".5, • "¾. •.: .•' '): : :: ' ,•,"t:'•?:-' :Sp{•:•: :• ..?:...,y'" ..½:.•:z? .,.•... •.'J•'5 ::,:•:• -• . . ½,• --•T-•.. . :•"-• •,, •.• .. ,, .•..::•.. •. '.2•.. ' •:.: -:•. •: • .•:• Cross-sections of Caucasian and Negro hair Laboratory, Prospect, N.S.W., Australia (39).* This wool is essentially nonmedullated, of 36's quality (mean diameter about 40 t•). 4. Merino Wool--Australian, of 64's quality. 5. Fiber Preparation--The fibers were Soxhlet-extracted with methylene chloride for 4 hours and then with absolute ethanol for 2 hours. They were then rinsed three times with deionized water, soaked in 0.01 N HC1 overnight, and washed in repeated changes of deionized water until the rinse water has a pH of 5. The fibers were then dried by exposure to an atmosphere of 65% R.H. and 70 øF, in which they were stored throughout the work. 6. Reagents--All the chemical reagents were of purified or higher grade. B. Results and Discussion 1. Morphological--Two features distinguishes Negro and Caucasian hair at the morphological level: the irregular crimp of the Negro fiber, presumably developed by the same mechanism which is responsible for the formation of crimp in wool (40), and the more oval shape of its cross- section p which twists irregularly as it progresses along the fiber axis ___ * Kindly stopplied by J. F. P. James, CSIRO Division of Textile Physics, Ryde, N.S.W. • The average ellipticity indices (ratio minor axis/major axis) for the two hair specimens of tiffs study are: Caucasian 0.71, Negro 0.56.

782 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS fibers of irregular section are occasionally evident (Fig. 9). In other respects--thickness of cuticle, shape and size of scale and cortical cells, for example--there is no discernible difference. Mercer (11) reports finding evidence of a bilateral slrueture (see II, 1) in the Negro hair cor- tex. Observations here suggest that, if there is any such differentiation, its magnitude is much smaller than that found in wool. Negro hair is typically heavily pigmented (Fig. 9). However, using the residue of hydrolysis in 6/V HC1 as a measure of the melanin content (41), it appears that brown Caucasian hair and black Negro hair are very much alike (Table IV). A significant weight of insoluble material is obtained when white Caucasian hair is subjected to this test micro- scopic examination of this residue shows it to consist largely of cell Table IX Urea-Bisulfite and Alkali Solubilities Solubility, Fiber Urea-Bisulfite Alkali Lincoln wool 52.5 10.4 Caucasian hair 27.0 5.0 Negro hair 37.2 4.1 Table X Cysteine and Cystinc Contents, Original Fiber Alkali Sol. Residue UB Sol. Residue Fiber CySH CySSCy CySH CySSCy CySH CySSCy Lincoln wool 0.31 9.8 0.43 0.77 0.91 4.42 Caucasian hair 0.78 17.2 0.46 2.23 1.66 11.4 Negro hair 0.66 17.8 0.46 2.57 0.96 11.0 Table XI Acid Hydrolysis, 0.04 N H2SO4, Reflux Fiber Weight Loss (r• After) Alkali Solubility Test, Following 4 Hours 18 Hours 4 Hours* 18 Hours* Lincoln wool 0.4 21.1 82.7 97.6 Merino wool . . . 21.4 ...... Caucasian hair 1.8 6.0 18.8 74.4 Negro hair 0.2 8.0 10.5 57.4 * Based on original weight, prior to acid exposure.