374 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Our 1991 study shows that there is a significant link between the two methods despite the different aspects of roughness that they measure. This is not disputed by Wortmann and Wortmann. However, with a correlation of r = 0.48 between the two methods, it is completely unreasonable and misleading to try to predict the results of the one method from the results of the other. The Wortmann and Wortmann analysis suggests that such predictability must prevail for cosmetic products to be tested reasonably with one method or the other. This assumption is incorrect. The two methods provide valuable, complementary information on aspects of skin roughness, as can be seen in the literature (2,3). The validity and reproducibility of the individual methods in their own right are fully unknown to Wortmann and Wortmann, and cannot be deduced from our 199 ! publication because no separate data was presented there. Consequently, Wortmann and Wortmann's inferences are unfounded and incorrect. In particular, image analysis, which we have used in commissioned work to measure the skin-smoothing effect of various commercial products, does allow cosmetic skin care products to be tested with regard to their skin-smoothing effect. Even slight smoothing effects of approximately 5% can be proven in a manner that is statistically significant. Wortmann and Wortmann's classification of products (very good-unacceptable) may be conclusive in mathematical terms but it has no foundation whatsoever as far as science, skin physiology, and the actual test design are concerned. REFERENCES (1) K. Schrader and S. Bielfeldt, Comparative studies of skin roughness measurements by image analysis and several in vivo skin testing methods, J. Soc. Cosmet. ½hem., 42, 385-391 (1991). (2) R. Bimczok et at., A multi center comparison of different test methods for the assessment of the efficiency of skin care products with 368 human volunteers, IFSCC, Yokohama (1992). (3) K. Wittern, Hautpftegeprodukte, Kreuznacher Symposium (Verlag ffir die chem. Industrie H. Ziolkowski KG, Augsburg), p. 58. (4) P. Corcuff et at., A fully automated system to study skin surface patterns, Int. J. Cosmet. Sci., 6, 167-176 (1984). (5) P. Corcuff et al., Evaluation of anti-wrinkle effects on humans, Int. J. Cosmet. Sci., 7, 117-126 (1986). (6) F. J. Wortmann et al., The methylene blue and image analysis tests for determining skin roughness: A critical assessment based on data in the literature, J. Soc. Cosmet. Chem. (September/October 1993). Karlheinz Schrader Stephan Bielfeldt Creachem GmbH Forschungsinstitut fiir die kosmetische Industrie Postfach 11 43 37591 Holzminden, Germany

J. Soc. Cosmet. Chem., 44, 375 (November/December) Book Review MELANINS AND MELANOGENESIS, by Giuseppe Prota. Academic Press, San Diego, CA, 1992, 290 pages. This book summarizes the current state of the art in melanin research. It contains 224 pages of text and over 50 pages of references (covering over 1,000 citations up to early 1992). This field was last re- viewed thoroughly in the late 1960s by Nicolaus. Much has changed in the inter- vening years, and this book therefore rep- resents a valuable new reference source in this complex field. Dr. Prota is recognized as a work leader in melanin research, and in this book he presents a comprehensive evaluation of the chemical, biological and, to some extent, medical aspects of melanins. While he puts major emphasis on the chemistry and biosynthesis of these pigments, he does ef- fectively relate these aspects to their broader biological significance. The introductory chapter gives an over- view of the basic concepts and major issues in melanin pigmentation. Other chapters discuss melanin-producing cells and tyros- inase and the various types of melanins: natural/synthetic, eumelanins, neuromela- nins, and pheomelanins and trichochro- mers. The last three chapters are devoted to the biology of melanins, covering pigment cell metabolism, genetic and hormonal regulation of melanogenesis, and photobi- ology and photochemistry of rnelanogene- sis. Despite this diversity of subjects and the volume of information provided, it is to Dr. Prota's credit that the presentation is concise and very readable. While clearly meant to appeal to the specialist, most technical readers will learn much from this book. Overall, Dr. Prota presents an objec- tive, in-depth study of the status of re- search into the important field of melanin pigmentation. This book is essential read- ing for all scientists in this area.--KEITH C. BROWN--Director, Organic Re- search, Clairol, Inc. 375