THE KERATINIZATION PROCESS 267 



that, before commencing definitely to form " droplets " of cuticular 

 keratin, the cuticle cells form small amounts of fibrillar material (Birbeck 

 and Mercer, 1957). 



The laminated structure and the differing chemical nature of the several 

 component layers are responsible for some peculiar reactions. When hairs 

 are immersed in acidified chlorine water, which attacks keratin with the 

 production of low molecular weight osmotically-active substances, the 

 resistant surface membranes are inflated into bubbles by the water, which 

 enters the cell (Allworden's reaction) (Fig. 111). The bubbles may develop 



Fig. 111. Explanation of the appearance of bubbles on the surface of 

 hairs immersed in chlorine water (Allworden's reaction). The external 

 cell membranes are modified chemically and form a very resistant layer, 

 the epicuticle. When chlorine penetrates it and oxidizes the proteins 

 within the cell, lower molecular weight soluble compounds are produced. 

 The membrane is dilated by the entry of water owing to the high osmotic 

 pressure within the cell. 



to an extraordinary degree on hairs with elaborate frilly cuticular scales 

 such as bat hair (Muller 1939). The study of this phenomenon first led 

 Miiller to recognize the existence of specialized resistant surface membrane. 

 Lindberg (1949) obtained clear pictures of the membrane by mechanically 

 abrading wool fibres covered with well-developed bubbles. Bromine 

 water is less active. Bubbles form, but the skin is thicker and seems to 

 consist of the surface membrane and the more resistant portion of the 

 exocuticle. A variety of other sheaths and tubules can also be obtained 

 from the lamellar cuticular structures of hair which differ principally in 

 the amount of keratin remaining attached to the epicuticle (Mercer et al., 

 1949; Manogue and Moss, 1953; Lagermalm et ai, 1951). 



