ABSTRACTS OF PAPERS ON THE BIOLOGY OF HAIR GROWTH 39 phane intermediates has been made in hair, Rebell has recently isolated kynurenin from the yellowish hair of albino rats. In addition, we have observed that pheomelanic hair when illuminated with wave-lengths of 3,600 A. is fluorescent, and emits light varying from a dull orange to bright yellow. Yellow hair, the pheomelanic banding of agouti hair of rn•ice, guinea pigs and golden hamsters and human red hair show this effect. The fluores- cence of the mixture of 3-hydroxykynurenin and dopa in which hair follicles had been incubated was a dark orange colour resembling that of an alkaline extract of pheomelanic hair. "THE BEHAVIOUR OF PIGMENT CELLS AND EPITHELIAL CELLS IN THE HAIR FOLLICLE" HERMAN B. CHASE Biology Dept., Brown University, Providence 12, Rhode Island. In the germ region of the regenerating hair follicle there are two centres of growth, one around the dermal papilla and giving rise to the bulb, the other producing the elongated lower external sheath. The first portion of the inner sheath forms from the early bulb and more is added as the bulb descends. The cells of the matrix, the lower bulb, are indeterminate in that they can be mechanically displaced and still give rise to the three layers of the inner sheath and the three regions of the hair shaft. Melanocyte stem cells reside in the upper bulb which is derived from the germ region capping the dermal papilla. The mature melanocyte has short dendrites, the cell body projects into the cavity of the dermal papilla and it delivers granules to be engulfed by the recipient hair cells. The club and surrounding capsule are formed at catagen from cells of the bulb matrix, but only after the dermal papilla has become partially rounded. "THE ELECTRON MICROSCOPY OF THE MELANOCYTE" N. A. BARNICOT University College, University of London, London, W.C.1, England, and IV[. S. C. BIRBECK Chester Beatty Research Institute, Royal Marsden Hospital, London, S.W. 3, England. The examination of melanocytes from human hair bulbs with the electron microscope has allowed the mechanism of pigment granule formation to be studied. A.region near the nucleus of the melanocyte, corresponding to the Golgi region, contains numerous small vesicles these consist of an outer membrane with several concentric inner membranes. Melanin is deposited upon the vesicles, to form the completed pigment granules. These are then transferred to the cortical cells of the hair. Examination of albino hairs has shown that the complex membrane structures are synthesised by the melanocyte, but

40 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS do not become pigmented with melanin. found in the melanocy/e of human skin. Similar structures have also been , ,' "VASCULARITY AND PATTERNS OF 'GROWTH" A. DuRwxm) and K. M. Dept. of A naton,y, University of Leeds, Leeds 2, Englan#. The blood supply to skin and to hair has been reviewed and variations in the supply to different types of hai•s and to hairs during the phases of growth have been studied, particularly in the rat and the rabbit. In the rat the monotrich has a rich supply from a dense network of capillaries around the lower half of the follicle and the dermal papilla contains capillaries awls have a less dense plexus of capillaries around the follicle and no papillary capillaries the smaller follicles do not possess individual plexuses, nor do they have vascularised papillae. In naturally occurring hair growth waves, as seen in the rat and the rabbit, the wave of hair growth is accompanied by a corresponding intensification of the blood supply which keeps step with the growth or recession of the follicle. These vascular changes have been studied in detail in the animals mentioned. Artificially induced growth of hair by pulling and the associated vascular changes were studied in the rabbit, and again a clear inter-relationship was established between hair growth and the vascularity. Local erythematous and eedematous phenomena occur in the skin following pulling. Pulling single ga•ard hairs in rabbits does not induce regrowth. There is a critical number of fibres (varying with conditions), which must be pulled before regrowth is started immediately. This shows that the act of pulling in itself is insufficient to cause immediate commencement of growth in a single follicle. "}¾IITOTIC ACTIVITY OF THE FOLLICLE" W. S. BULLOUGH and E. B. LAURENCE Dept. of Zoology, Birkbeck College, University of London, London, England. 1. The distribution of mitotic activity in the growing follicle of the adult mouse is described. In the fully grown follicle such activity is confined to the matrix cells of the bulb. 2. Observations in vitro (a) It is shown that, for the development of active mitosis in a hair bulb, adequate supplies of oxygen and of some suitable carbohydrate substrate are essential. In the absence of either, the mitotic activity is powerfully inhibited. (b) Ideal carbohydrate substrates for the support of mitotic activity