JOURNAl. OF THE SOCIETY OF COSMETIC CHEMISTS 509 Table I Percentage of Total Nitrogen Cysteic Fraction Acid Lysine Arginine Serine a-keratose (microfibrils) 3.72 4.60 20.8 6.70 •-keratose (matrix) 14.5 1.03 19.0 9.70 Astbury who stressed the need to supplement the measurement of dimensional changes by X-ray examination, his most striking evidence being that a supercontracted fiber might give a disordered E-photograph, the supercontraction in such a case being due to disorientation of E- crystallites and not to loss of set by transformation of •-keratin (set keratin) into a-keratin. So far as I am aware, corresponding X-ray and dimensional studies of fibers (a) set at low temperatures and (b) afterward relaxed in boiling water have not been made. This is unfor- tunate, because a clear understanding of the fate of both the crystalline and amorphous regions in low-temperature setting is essential as a basis for the development of improved processes. AMXNO-AcxD SEQUENCE IN KERA. TIN FRACTIONS The slow growth of fundamental knowledge, as well as delay in using what is available, is a more serious barrier to technical advance. All possible support should be given to determinations of the amino-acid sequence in the various fractions of keratin, because until this informa- tion is available there can be no constructive study of improved methods of cross-linking keratin, which must be the basis of improved methods of cold permanent waving. To see how imperfect is our present knowl- edge we need only ask why it has so far been impossible to set strained fibers with alkalies at low temperatures, using conditions which promote the formation of lanthionine cross linkages, when such setting is possible with potassium cyanide according to the following reaction scheme: R--S• R d- KCN --• R--SK d- R--SCN --• R--S--R d- KCNS It seems unlikely that the answer is connected with the fact, which has emerged from recent work on the amino-acid sequence in wool keratin (3), that certain of the peptide bonds are highly sensitive to attack by alkalis. This knowledge does, however, suggest that some advantage may be found in using neutral or mildly acidic linkage-rebuilding agents with reduced keratin in the conventional low-temperature permanent

JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table II Percentage Reduction in Resistance to 25% Extension in Water Reduced Reduced and Reagent Fibers Oxidized Fibers Mesoxaldehyde 33.3 14.8 Dehydroascorbic acid 33.1 13.0 Pentan-2: 3: 4-trione 31.1 12.9 Cyclopentan- 1: 2: 3-trione 31.1 - 0.6 waving process. How effective these agents are will be seen from the results of Table II (4). The fibers were first reduced with thioglycollic acid (M) at pH 4.55 and 25 øC for twenty-four hours, washed overnight in running water, and then treated with a 2.5% solution of a vicihal tricarbonyl compound at 25 øC. INTERNAL POLYMERIZATION As a direct consequence of the lack of knowledge of the amino-acid sequence in the keratin proteins, and the difficulty of making a construc- tive attack on cross-linking problems, much attention has been given to the synthesis of polymers inside animal fibers as a means of modifying their properties. Many methods have been evolved, usually for use with vinyl compounds, but in the case of permanent waving they are commonly associated with two disadvantages, swelling of the fibers and a reduction in the affinity for water both of which harm the feel. Hydrophilic polymers are dearly desirable, and it is interesting that an aqueous solution of reductone (10%), which is slightly acidic, poly- merizes inside wool fibers at 25 øC without any assistant (4). Although the polymer is hydrophilic, the resistance of the fibers to 25• extension in water can be increased by as much as 54%. Compounds of this general type are likely to find important uses in modifying the properties of keratin, at least until the results of more systematic studies of cross linking become available. SURFACE DEPOSITS OF POLYMER More important than the fmmation of polymers inside keratin fibers at the present time, is the application of preformed polymers from solution to the surface of the fibers for the purpose of improving appear- ance and feel. Rapid systematic progress in this field is possible with the Stereoscan--the Cambridge scanning electron microscope. It cer-