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A short-time treatment for isolating epicuticle from wool is described. Electron micrographs showing the penetration and disintegrating of the epicuticle caused by dilute Na 2 S or KOH are shown. These phenomena and their connection with the increased dyeing velocity and some other phenomena after treatment with alcoholic KOH are discussed. Experimental ProcedureThe epicuticle of wool-that is, the thin membrane covering the fiber surface-was first isolated by treating wool with dilute Na2S at room temperature [5]. This procedure is, however, rather time-consuming, as it requires at least a month to carry out. A more rapid method, which yields samples of almost equal quality, is to treat wool with 1% Na-2S solution at 60°C for about 24 hrs. and then with a solution of the same concentration at room temperature for about 1 wk. Since after standing some time solutions of Na2S often will form precipitates or become discolored, it is recommended that the wool residue be washed after the elevated-temperature treatment so that impurities originating from the Na2S can he avoided.It is very difficult to get the epicuticle absolutely pure. Electron microscopy reveals that a great part of the membranes in a specimen can be obtained completely free from adhering substances, but that there will at the same time be some membranes with adhering bits of the exocuticle. Also larger particles, including elements from the endocuticle, can be found in the same specimen. Figure 1 is an electron micrograph of a piece of epicuticle, isolated by the short-time treatment and rather free from adhering substance. It has been shadowed with gold-manganin at an angle of 4: 1. (The wool had been subjected to a treatment with 2% KOH in ethyl alcohol for 5 min. before the Na2S treatment. This is irrelevant, as the same results have been ob-FIG. 1. Epicuticle) isolated by the short-tz1ne treatment with dilute Na2S, and rather free f rom adhering substances. Shadowed with gold-manganin.

IntroductionStudies by Lindberg, Philip, and Gralen [7] revealed that the wool fiber is covered by a thin membrane, the epicuticle, with a thickness of an order of magnitude of 100 A. This membrane can be separated from the fiber by different chemical methods. Elementary analyses of these membranes give different chemical compositions for the different methods employed [5]. Similar membranes can be separated from other structures of animal origin [6, 15, 16~ . From studies of the formation of the Allw6rden blister, Lindberg [8 J concluded that the epicuticle forms a continuous skin over the whole fiber. A review of the role of this membrane was given by Lindberg, Mercer, Philip, and Gralen [9]. However, doubt has been aroused as to the validity of the conclusion of the continuous skin and the sufficiency of the underlying experimental evidence. Zahn [19], for instance, stated that every scale is surrounded by a thin membrane, and O'Reilly et al. [12] made a similar suggestion. FIG. 1. The exocllticle layer becomes thinner ~eith increasing distance f royn the scale edges. The edge in the middle, common to the two scales, likewise becomes thinner; finally the surface layers fronz both scales end zep in a comyrton layer of epicuticle. Phenol-tr}'ptic digested specimen, deposited on SiO, 1tnshadoll'ed. Phenol-Tryptic DigestionTreatment with phenol at 100° C for 2 hrs. followed by digestion with trypsin at pH 8-9 gave specimens in which the scaly structure still could be recognized [10]. These studies have been continued. Figure 1 is from a preparation obtained by this method. The specimen is unshadowed and deposited on a SiO membrane. The scale edges are rather thick, but the exocuticle layer adhering to the part next to them gets thinner with increasing distance from the edges. The edge in the middle, common to the two scales forming the specimen, likewise gets gradually thinner, and finally both scales end up in a common sheet of epicuticle, free from contaminating substance. Iv r i -----4 FIG. 2. Tlze ends of a scale edge end bll*ndIN, ill a sheet of epicnticle and adhering exocuticle. The streakiuesss, 'With a periodicity of approximatel;;, O.3I-L, riiiis contin2c-ollslJ' from tlze one scale to tlae other. Phenol-try~tie digested specimen, Pd-shadO't,l'ed at an angle 4:1. at FLORIDA INTERNATIONAL UNIV on June 28, 2015 trj.sagepub.com Downloaded from 18 FIG. 3. Ridges (curled or corkscrew-shaped structures running parallel to the main directiove of td2e scale edges) are seei/. Oite of theaaz protrudes from the scale edge and seems to be reiiaforcing it. A string runs between tzoo scale edges. Tlze streakiness r2cvas ivc the length direction of the fiber. Phenol-tryptic digested specÍ1nen, deposited on SiO, unshadowed. FIG. 4. Striated surface-layer sl2eet with strings and the curled remnants of a ridge. The holes are located on the strings. Phenol-tryptic digested specimen) Pdshadowed at an angle 4: 1.Figure 2 shows part of a specimen from the same type of preparation, but which is Pd-shadowed at an angle 4: ...

Dye rates were measured for unsteamed and steamed solvent-extracted wool. These meas urements indicate that the dye rates for wool that has not been alkali-damaged, or wool in which the alkali damage has been restricted to the fiber surface, are not influenced by steaming. The dyeing time for wool treated with an aqueous alkaline solution is increased considerably by steaming. This would indicate that the effect of steaming is due to modifications in the bulk of the wool fiber.