286 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS SPECIAL EDITIONS The following special editions are available. Ten-Volume Index, 1947-1959 Price $2.50 Seminar on Percutaneous Absorption Price $5.00 Prepaid orders may be sent to: Editorial Assistant 2758 Pine Hill Drive Birmingham, Michigan

BOOK FUNDAMENTALS OF KERATINIZA- 'nON, edited by E. O. Butcher and R. F. Sognnaes. Publication No. 70, American Association for the Advancement of Science, Washing- ton, D. C. 1962. 189 pages, illustrated and indexed. Price $6.$0 ($5.75 to AAAS members). This small volume comprises papers presented at a symposium held by the American Association for the Advancement of Science in December, 1960. Most of these papers are original, and this volume is, therefore, of major interest to the workers in the field of keratin. The first paper in this book, by Matoltsy, is concerned with the role of keratohyalin in keratiniza- tion of mammalian epidermis. On the basis of histological studies, the author concludes that epidermal cells keratinize independently of one another and that tonofilaments and keratohyalin granules are differen- tiation products formed for in- corporation into the elaborated keratin. In another interesting chapter, Szab6 concludes that there is a difference between the embryonic and adult basal cells of the epider- mis: In the embryonic stage, these cells are self-differentiating, whereas basal cells in the adult epidermis are not self-differentiating. Rhodin and Reith, in their papers on the ultra structure of keratin again, return to the role of kerato- hyalin in keratinization. The pur- pose of keratohyalin has been in dispute ever since it was first dis- covered, and various workers have interpreted their observations dif- REVIEWS ferently. Mercer and his group have always maintained that kerato- hyalin is transformed into fibrils. These authors assign to keratohyalin a somewhat different role and in- dicate that keratohyalin aggregates with tonofilaments only during the formation of soft keratin. In con- trast, the formation of hard keratin and of amorphous keratin do not seem to require keratohyalin. Cosmetic chemists will be in- terested in the papers from a num- ber of groups concerned with the influence of Vitamin A on keratini- zation. Bern and Lawrence con- clude that the effect of Vitamin A on keratinizing epithelium varies as a result of dosage. On the other hand, Parnell and Sherman conclude that Vitamin A can be utilized directly by excised tissue and stimu- lates tissue mitotic activity at moderate dosage levels. One of the most interesting ob- servations in this volume concerns the one by Watson on the extracellu- lar position of dental enamel. Wat- son concludes on the basis of some beautiful electron photomicrographs that there is a cell membrane between the ameloblast and the enamel, indicating that enamel is fo•med extracellularly. Similarly, the last chapter of this book by Piez demonstrates that the protein matrix of enamel from human teeth, at least on the basis of amino acid composition, is not a true keratin and instead resembles collagen. It is equally interesting that this protein normally cannot be isolated unless the teeth have been treated with formaldehyde. 287