EFFECT OF BILATERAL STRUCTURE ON KERATIN FIBERS 355 (4) Conrad, L. I., 5 e. Soc. Cosmetic Chem., 5, 11 (1954). (5) Gillespie, D. T. C., "Wool Wax," Washington, D.C., Hobart Publishing (1948). (6) Croda Publication, "Lanolin" (1951). (7) Drekter, I. J., and Conrad, L. I., U. $. Patent 2,302,678 (1942). (8) Jenkins, G. L., and Hurtung, W. H., "The Chemistry of Organic Medicinal Products," 3rd edition, New York, John Wiley and Sons (1949). (9) Greenberg, L. A., and Lester, D., "Handbook of Cosmetic Materials," New York, Inter- science Publishers, Inc. (1954). (10) Sulzberger, M. B., and Lazar, M.P., •7. Investigative DermatoL, 15, 453 (1950). (11) Sulzberger, M. B., Warshaw, T., and Herrmann, F., Ibid., 20, 33 (1953). (12) Warshaw, T. G., •7. Soc. Cosmetic Chem., 4, 290 (1953). (13) Everall, J., and Truter, E. V., •7- Investigative DermatoL, 22, 493 (1954). THE EFFECT OF BILATERAL STRUCTURE ON THE CHEMISTRY OF KERATIN FIBERS* By J. H. DtYSENBUP,¾ and E. B. JEFFRIES Textile Research Institute, Princeton, New yersey INTRODUCTION Much or THE WORK discussed here has been done by others at Textile Research Institute in addition to the authors of this paper. Work under way on the Wool Research Project at Textile Research Institute includes the investigation of methods that may be used to characterize various natural protein fibers in terms of the ortho-para behavior of the particular fiber cortex. This paper is in the nature of a progress report on what has been accomplished so far. Before going into this work, however, a brief summary of the previous history of the idea of a bilateral structure for wool fibers is in order. In 1953, Horio and Kondo in Japan showed that a wool fiber dyed with a dilute solution of the basic dyestuff, Janus Green B, exhibits a bilateral staining effect (7). When viewed longitudinally, one-half of the dyed fiber appears to be dyed more heavily than the other half and this bilateral structure runs the entire length of the fiber from root to tip. Furthermore, the more heavily stained portion always appears on the outer, convex side of the crimp wave and appears to go from one side of the fiber to the other, in correspondence with the periodicity of the crimp. In Fig. 1 is shown a photomicrograph of a domestic fine wool fiber (64's grade) dyed with a dilute solution (0.1 per cent) of Janus Green B at pH 7. The bilateral structure is clearly apparent. This photomicrograph was taken under polarized light conditions, which tend to accentuate the bilateral effect observed with ordinary light. Horio and Kondo also showed that * Based in part on the paper presented at the September 23,1954, Seminar, New York City.

35(, JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Figure 1.--A 64's wool fiber (Rambouillet), dyed with Janus Green B, viewed in polarized light (X 80). the two components of the cortex differ from each other in swelling in alkali, and in birefringence after exposure to alkali and that they appear to be in the form of hemicylinders wound round each other helically in phase with the fiber crimp, so that one component is always placed at the outer side of the crimp curvature, with the other component at the inner side. In 1938 in Japan, Ohara demonstrated the differential dyeing effect on fibers dyed both in bulk and as cross sections with basic dyes (10). He pointed out that in the case of a basic dye, such as Janus Green B, the convex outer portion of the crimp curvature is preferentially stained. He appears to have had limited success with acid dyes in this regard, but did claim that Orange G preferentially stained the concave inner side of the crimp curvature in some experiments. In 1939, Ohara also published observations that these concave inner portions exhibit the greater bire- fringence (11). The later work of Horio and Kondo in 1953, referred to previously (7), confirmed the findings of Ohara that the differential dyeing effect may be observed on fibers dyed both in bulk and as cross sections and that a basic dye, such as Janus Green B, preferentially dyes the convex outer portion of the crimp curvature. These workers also reported that the acid dyes, Orange G and Ponceau 2R, preferentially stain the concave inner portions of the crimped fibers. Their views appear to have been shared by Mercer who in his 1953 paper (8) named the portion of the fiber more heavily dyed with basic dyes the "orthocortex." He demonstrated that this portion could be removed preferentially from the remainder of the fiber by a process of supercontraction and subsequent digestion with the enzyme trypsin. The remaining portion of the fiber cortex, which was named the "paracortex" by Mercer, is generally less reactive to chemical reagents. In Fig. 2, there appear two photomicrographs illustrating this effect. The procedure used