608 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS with you that this could be a weak point, it has not worked that way in fact, and the highest reactivity ratio obtained (which is an indication of affinity) was with azobenzene psulphonic acid, and was very much greater than with some of the much larger molecules. DR. H. G. TROTH: I would like to invert this experiment. Could you choose a single molecule and alter the hole size, and then use the molecule as a measure of the hole size of a particular level ? THE LECTURER: I would have thought that permanent waving would have altered the hole size. But apparently it does not. I do not know how to alter the hole size. PROE. C. S. WHEWELL: What do you really mean by hole size ? At what level of organisation do you believe these holes exist ? What relation do these holes have to microfibril structure, protofibril structure and the rest of it ? THE LECTURER: I am not sure whether the holes are within the helices, in which case the whole thing gets distorted, or whether they are between the helices. What do you think ? PROF. C. S. WHEWELL: It would appear to be quite a critical experiment to repeat your work on hair which is stretched by 30% and held stretched. This would alter the disposition in one direction. THE LECTURER: It is a good idea, and it helps Dr. Troth by varying the size of holes.

J. Soc. Cosmetic Chemists 15 609-630 (1964) ¸ 1964 Society of Cosmetic Chemists of Great Britain THE INVESTIGATION OF DANDRUFF N.J. VAN ABBE, F.P.S.* Presented at the Symposium on "Hair", at Brighton, Sussex, on 16th April 19•4. Dandruff should be regarded as a physiological abnormality involving a mild degree o• parakeratosis in the epidermis o• the scalp. The paper describes experimental studies to explore natural fluctuations in severity o• the condition and to examine the possibility o• an infectire origin. Cultural methods •or the study o• Pityrosport•rn ovale are described and the use o• ethyl oleate as a mild irritant to produce dandruff-like scaling o• mouse-skin is reported. INTRODUCTION Dandruff may be classified as a scalp condition characterized by excessive desquamation in the form of visible scales. This definition therefore implies a physiological abnormality, calling for diagnosis and investigation along the lines generally applied to pathological syndromes. Dandruff appears in the literature, often within the generic category of "seborrhoeic disorders", under several headings, such as seborrhoea sicca, seborrhoea oleosa, pityriasis capiris and pityriasis simplex. However, evidence of dis- ordered sebaceous activity as a precursor or consequence of dandruff is lack- ing even the distinction between "dry" and "greasy" forms of the condition is purely empirical. The only obvious connection is that dandruff is usually confined to regions of the skin where sebaceous activity is maximal. Before a rational approach to therapy can be contemplated, it is necessary to have more detailed information on the "natural history" of dandruff, and this paper indicates some of the avenues we have explored. THE CLINICAL PATTERN Reports on therapeutic measures against dandruff seldom include proper controls, and show little evidence of any attempt to record observations systematically or to analyse the findings statistically. In view of the apparently insurmountable difficulty of directly recording the amount of scaling, we found it necessary to devise a simple visual index for use on different subjects by a team of trained observers with demonstrable reliability. * Toiletry Division, Beecham Group Ltd., Brentford, Middlesex. 609