74O JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS of the substrate--whether human or animal skin and the area involved, the time available, and the cost. (Received: oe7th May 1971) REFERENCES (1) Daniels, F. and Imbrie, J. D. Comparison between visual grading and reflectance measurements of erythema produced by sunlight. J. Invest. Dermatol. 80 295 (1958). (2) Kahn G., and Wilcox, G. Comparison of in vitro and in vivo sunscreen testing methods. y. Soc. Cosmet. Chem. 20 807 (1969). (3) Lerner, A. B., and McGuire, J. S. Effect of a- and [•- melanocyte stimulating hormones on the skin colour of man. Nature 189 176 (1961). (4) Tronnier, H. Evaluation and measurement of ultraviolet erythema. In Urbach, F. The biologic effects of ultraviolet radiation 255 (1969). (Pergamon, Oxford). (5) Runge, W. J., McHugh, R. B. and Johnson, L. W. The detection of acute erythema in pigmented and non-pigmented bovine skin by measurement of its spectral reflection. j[. Invest. Dermatol. 46 198 (1966). (6) Breit, R. and Kligman, A.M. Measurement of erythemal and pigmentary responses to ultraviolet radiation of different spectral qualities. In Urbach, F. The biologic effects of ultra violet radiation 267 (1969) (Pergamon, Oxford). (7) Edwards, E. A. and Duntley, S. Q. The pigments and colour of living human skin Am. J. Anat. 65 1 (1939). (8) Jacquez, J. A., Kuppenheim, H. F., Dimitroff, J. M., McKeehan, W. and Huss, J. Spectral reflectance of human skin in the region 235-700 mp. y. Appl. Physiol. 8 212 (1955). (9) Weiner, J. S. A spectrophotometer for measurement of skin colour. Man 51 152 (1951). (10) Barnicot, N. A. Reflectomerry of the skin in southern Nigerians and in some mulattoes. Human Biol. 30 150 (1958). (11) Harrison, G. A. and Owen, J. J. T. Studies on the inheritance of human skin colour. Ann. Human Genet. 28 27 (1964). (12) Jarrett, A. The melanocyte system and keratinization. J. Soc. Cosmet. Chem. 18 413 (1967). (13) Jolles, B. and Mitchell, R. G. A hand Tintometer for radiological and dermatological work. Lancet 1 1333 (1957). (14) Jolles, B. and Greening, S. G. Studies of indirect radiation effects with skin grafting experiments and colorimetric estimations of erythema. Brit. J. Radiol. 31 136 (1958). (15) Gibson, I. M. A modified Lovibond Tintometer using fibre optics for the measurement of surface colour. Lab. Pract. 1õ 999 (1966), (16) Judd, D. ]3. and Wyszecki, G. Colour in business, science and industry, 2nd edition. 221 (1963) (Wiley, London). (17) Pfleiderer, H. Zur Methodik der Erythem-und pigmentmessung. Proc. 1st oentern. Photobiol Congr. Amsterdam 248 (1954). (18) Nealon, D. F. A study of the skin lightening effects of ammoniated mercury. Proc. Sci. Sect. Toilet Goods Assoc. 1 7 (1944). (19) Lunnon, R. J. Direct ultra-violet photography of the skin. Med. Biol. oellustr. 9 150 (1959). (20) Callender, R. M. The technique of in vivo close-up photography using ultraviolet radiation. Ind. Comml. Photogr. 11 42 (1971).

J. Soc. Cosmet. Chem. 22 741-755 (1971) ¸ 1971 Society of Cosmetic Chemists of Great Britain The dermal development papilla and the and growth of hair R. F. OLIVER* Presented on loth March 1971 in Eastbourne, Sussex, at the Symposium on "Appendages of the Skin", organised by the Society of Cosmetic Chemists of Great Britain. S•,nopsis--Dermal-epidermal interactions in the development and growth of S KIN appendages have been reviewed. Particular emphasis has been placed on the dermal papilla of the HAIR FOLLICLE because, apart from its importance in the ONTOGENETIC development of hair follicles, it has also been shown to induce follicle development from adult EPIDERMIS, and ORAL EPITHELIUM, and to induce hair growth in the adult follicle. It is suggested that the dermal papilla may also be involved in the termination of hair growth at CATAGEN and in the determination of FIBRE characteristics. It is further suggested that the intrinsically determined properties of hair follicles may reside in the dermal component of the follicle. INTRODUCTION The hair follicle presents a number of problems of biological, cos- metic, economic and social interest. Perhaps the most intriguing are the elucidation of the factors which control the intermittent production of hair from a follicle, those which determine the characteristics of the hair, and those which are involved in follicle maintenance. The hair follicle, in common with skin and its other appendages (e.g. feather follicles, teeth and scales), is essentially composed of epidermal and dermal tissues which derive from the outer embryonic ectoderm and the underlying mesoderm. Enveloping the epidermal component of the hair *A.R.C. Institute of Animal Physiology, Babraham, Cambridge. Now at Department of Biological Sciences, The University, Dundee, Scotland, DD1 4HN. 741