HAIR AND WOOL 783 membrane fragments. The values of the last column in the Table show that 6/V H•.SO4 leaves a similar amount of residue. One racial difference in the pigment has been reported, though on the basis of a very limited sample. Using the electron microscope, Swift (42) had measured the size of isolated melanin granules and found those from Negro hair to be larger than those from Caucasian (and also Chinese) hair. 2. Ct?emical Composition--Table V lists the results of amino acid analyses, performed by column chromatography on the three fiber samples.* Acid hydrolysates were used tryptophan, if present, was thus destroyed. Methionine was not detected in any of the samples. The results for the Lincoln wool and Caucasian hair are in general agreement with those reported by others (17). The main interest resides in the Caucasian-Negro hair comparison. Here, the only notable differences are the deficiency of serine and threonine and the excess of tyrosine, phenylalanine, and ammonia in the Negro hair. One cannot place any meaningful interpretation on these data at present. Another indication of the chemical structure is given by fractionation into "keratoses," using the method developed by Alexander (43), which is based on oxidation with peracetic acid and dissolution in aqueous ammonia. The fraction insoluble in the ammonia, which is termed •-keratose, is believed to consist of cell membranes and similar material. The fraction precipitated by the adjustment of pH down to 4, called a-keratose, is thought to originate from the crystalline portion of the protein and the residue, •,-keratose, from the amorphous protein of high sulfur content. The values for the two hair samples were determined by the pro- cedure of Corfield, Robson, and Skinner (34) the sulfur contents were determined by the oxygen combustion method of Parisot (44). The results are given in Table VI, along with those reported by Corfield et al. for Merino wool. The two hair samples fractionate almost identically. Compared with the wool, they are higher in •- and •,- and lower in a-keratose, which indicates that the hair contains a higher proportion of amorphous, high- sulfur material. The sulfur contents of all three fractions are higher in the hairs, which is indirect evidence to the effect that the fractions are themselves complex mixtures of proteins and protein degradation products. Interestingly, the proportion of the sulfur content of the * We are indebted to Dr. E. Gross of the NIAMD, NIH, Bethesda, Md., for these data.

784 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 0.8 •,. 0.6 - z 0.4 0.2 NEGRO HAIR q,. ........... © .... o-8 ,C::)__ 0 f CAUCASIAN HAIR := / • 0'6 / +_,. p,a•-'--' "' WOOL •_ • 0'4 0 '"' 0'3M TGA • 0'6M NH,• OH • / pH 9'3 • 0'2 // 36øC 125:1 BATH / i I i 20 40 60 TIME, MINUTES Figure 10. Rate of reduction in alkaline thioglycolate CAUCASIAN HAIR ....0"'" • NEGRO HAIR • &,,-,-,,, WOOL I M NH,• HS03 NH,• OH to pH 6.0 36øC 125:1 BATH __ L I I 0 20 40 60 TIME MINUTES Figure 11. Rate of reduction in sulfite at pH 6 WOOL /8 -'- o • 40 / •- NEGRO HAIR / = '•e / 0'3M TGA lad = 0'6M NHa OH 2O - /0•,,,, pH 9'3 ! CAUCASIAN HAIR 36oc /•/ 125:1 BATH t / ! I , I 0 20 40 60 TIME, MINUTES Figure 1•. The data of Figure 10 replotted in terms of fraction of disulfide bonds rup- tured wool recovered in the three fractions is lower in hair (68-70%) than in the wool (78%). The proportion of material unrecovered is the same this must, therefore, have a higher sulfur content in the case of the hair. 3. Acid Binding and Moisture RegainsThe acid binding of Cauca- sian and Negro hair has been compared by Sagal (45) no difference was found. The,absence of pigment has no influence on the result in either kind of hair.