FLORA OF SCALP AND DANDRUFF 121 Noble (Difco) was made in each of the six basal isolation media. Into each Petri dish 25 ml was poured. Scurf was sprinkled heavily on each hardened medium with sterile forceps. Following incubation and growth, every different kind of colony was examined and studied micro- biologically. Silica Gel Base Cultures--Silica gel was incorporated into each of the isolation media. The silica gel was prepared according to the method of Pramer (22). Flask Broth Cultures--Approximately 20 mg of scurf was placed into sterile 50-ml flasks containing 25 ml of basal isolation media. At incuba- tion periods of 1, 3, 7, 14, and 30 days, 0.1 ml of broth culture was re- moved and streaked on the surface of the corresponding solidified basal medium containing 1.5% Noble Agar and 0.1% scurf, sterilized by ethylene oxide. Percolation Apparatus Broth Cultures--The technique used was a modification of the soil percolation apparatus described by Temple (23). The mechanism of operation is described in detail by Lees and Quastel (24). The specific measurements and photographs of the hand-blown apparatus used in this research can be found in the original thesis of Roia (25). Such an elaborate method insured the isolation of slow growing or- ganisms. It also maintained constant aeration, and it provided for a method of removing samples of broth culture without disturbing the scurf. Identification of Cultures Yeasts--The techniques and media used to identify yeast isolates were those described by Lodder and Kreger-Van Rij (26). These meth- ods have been summarized by Roia (27). Molds--The identification of molds was based upon the examination of wet mounts prepared from 10- to 12-day old cultures grown on Czapek Solution Agar (Difco) at 25 øC and upon the examination of slide cultures* using Corn Meal Agar (Difco) as the nutrient. Three taxonomic keys (28-30) were used to identify the families and genera. Lewis et al. (31) were also very helpful in classification. Other references to keys used in the identification of genera are included under "Results." * Shoe•naker Fungus Microculture Slides, manufactured by Clay-Adams Co., Inc., New York.

122 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Bacteria--All microscopic studies and subcultures were made from 24-hour old cultures. The isolates were initially classified into four groups: gram-positive .cocci, gram-negative cocci, gram-positive rods with or without spores, and gram-negative rods. These groups were [urther subdivided on the basis of an anaerobic glucose fermentation study (32). All bacteria placed in a particular group were studied and classified according to the methods of Bergey (33), unless stated other- wise. Actinomycetes--The media and methods of separation and identifica- tion of the actinomycetes were based upon the criteria of Waksman (34). Keys and methods described in Bergey (35) and in Waksman and Leche- valier (36) were also used. RESULTS Questionnaire Survey Of the 502 students surveyed, 70.1% stated that they had a dandruff problem. The two most common degrees of dandruff were moderate dandruff (33.7%) and mild dandruff (30.3%). Scurf Weights The average individual scurf weights of 52 subjects varied from 13.3 to 200.0 mg. Scurf weights seemed to increase daily and the last sample was almost always heavier than the first. There were frequent fluctua- tions in the scurf weights of successive samples which occurred in the majority of volunteers. It was noticeable that all subjects with an average scurf weight of 40 mg or more showed visible signs of exfoliation, and those with less than 40 mg displayed no signs of dandruff. Using 40 mg as the criterion for diagnosis, there were 28 subjects with dandruff and 24 without dandruff. Further separations based upon scurf weights were made arbitrarily, and this information is summarized in Table I. Direct Smear Observations ?ityrosporum ovale was observed in 86.5% of all subjects. Its oc- currence was more frequent in subjects with dandruff (96.4%) than in those without dandruff (75.0%). The prevalence of this organism is tabulated in Table II. ?ityrosporum orbiculare occurred in 76.9% of all subjects. It was observed that ?. orbiculare was always less prevalent on the individual scalp than P. ovale. Of the subjects with dandruff, 82.1% had _P. orbiculare whereas only 70,8% of those without dandruff had this or-