JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS those applicable in engineering, such as certain phases of mathematics and physics, can be called the "engineering sciences." In either case, the applic- able sciences have become so varied, so involved, and so vast that the amount of material to be included in any compendium is limited only by the ambition, energy, and resources of the author. These analogies may assist us in forming a concept of the "cosmetic sciences." Although we call ourselves "cosmetic chemists," chemistry is by no means the only science which impinges upon cosmetic technology. Chemistry is, however, the science most widely used by us in establishing the theoretical foundations of our profession. More and more of the knowledge used by us is being expressed in chemical terms, as description gives way to analysis. Much of the descriptive material now available for our use is classified under such headings as anatomy, morphology, histology, cytology, physio- logy, pharmacology, dermatology, microbiology, etc. The progress of science is signalised, however, by the definition and explanation of structures, substances, and processes in terms of physical and chemical concepts. Biological concepts acquire greater meaning and usefulness for us when broken down into their chemical components. We are therefore justified in referring to the scientific basis of our technology as cosmetic chemistry. Our industry makes use of a great deal of technological data which is not yet sufficiently organised and explained to be classed as scientific material. It was probably to be expected that in our Society's first ten years techno- logical papers should outnumber scientific by 130 to 23. With the tech- nological phase so well covered, more attention can now be given to the underlying science. Cosmetic chemistry includes all chemical generalisations, theories, and concepts which can be utilised to enhance the safety, effectiveness, and acceptability of cosmetic preparations. Cosmetic theory is at present severely limited because of: A. Incomplete communication, interpretation, and application of data in the literature of chemistry, physiology, pharmacology, etc. B. Incomplete understanding, even among the pioneers in the under- lying sciences, of the mechanisms involved in cosmetic treatment. Many of the papers presented before our Society in the past, especially those designated as dealing with scientific topics, have served to communi- cate to our members data which contribute to their understanding of cosmetic problems. Possibly it will be of interest to mention a few of our current problems, to consider recent advances toward their solution, and to record some of the unanswered questions that we hope can eventually be answered. The panorama thus outlined may assist in delineating the emerging cosmetic chemistry.

THE EMERGING COSMETIC INDUSTRY 29 COMPOSITION AND FUNCTION OF TISSUES If cosmetic preparations are to be so formulated as to protect the skin effective]y, or to improve its condition, the fullest possible know]edge of the structure of the skin and the chernical composition and function of its com- ponents is desirable. Present knowledge of skin structure is unfortunately far from adequate, and many morphological features are known only vaguely. The chemical composition of important components is even ]ess completely known. Rothman's recent compendium, "Physiology and Bio- chemistry of the Skin, "• performs admirably the function of summarising and organising data published up to 1952 on these topics, and on the functioning of skin tissues. Connective Tissue. The tendency of ageing skin to wrinkle and sag is apparently connected with a loss of elasticity, which is in turn, at ]east partially, traceable to changes in the structural elements of the corium or curls. In the connective tissue of the cutis, three types of material can be distinguished, namely, cells, fibres and matrix. The matrix appears homo- geneous under the light microscope, but the electron microscope shows that it contains a fine network of fibrils. Collag•n. The fibres of connective tissue are of three types: Co]lagen, reticu]ar and elastic. Co]lagen fibres are greatly preponderant there is no agreement as to how they differ chemically from the branching reticulin fibres. Recent evidence 2 indicates that co]lagen of leather contains large numbers of extremely small pores, with radius of the order of 100A. Kennedy-' recently obtained electron micrographs of sections of co]]agen fibrils from various sources showing tubular structure in the fibrils. Such evidence adds support to the view that co]]agen may serve not only as a structural unit, but also as a conductor for transporting substances toward nomvascularised tissues. • The method of formation of collagen is very incompletely understood its prominent presence in new repair tissue, and the recent report that injections of Irish moss extract stimulated growth of repair tissue in rats • contribute to our desire to know more about co]lagen formation. Knowledge of the chemical composition of collagen is incomplete. Pauling and Corey, • in working out a proposed helical structure, had used the sequence -P-G-R-, where P is proline or hydroxyproline, G is glycine, and R is one of the other amino acid residues, as the typical repeating unit of collagen. Kroner, Tabroff, and McGarr, • however, recently isolated 28 new peptides from collagen hydrolysate and showed that in the 68 collagen peptides now known only 15 contain the P-G-R- sequence. They found the proline-hydroxyproline linkage to be strongly represented. Gustarson • cited the apparent relation between the hydrothermal stability of collagen and its hydroxyproline content as an indication that the hydroxyproline