220 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS EXPERIMENTAL Twenty women employees of the Gillette Research Laboratory were used for this study. They ranged in age from 24 to 59 years, with 17 of them between 24 and 42. The three oldest panelists were Chinese all others were Caucasians. Within the Cau- casian group, the hair color ranged from light blond for 2 panelists to a nearly black, dark brown for 2 panelists. One panelist had reddish hair, but most had hair color in . the brown range. The ancestry of the Caucasians--when known--varied from Scandi-.: nayJan to Mediterranian. All 3 Orientals were born in China. A minimum of 12 cm hair length and the absence of Negroid-type curliness were the only criteria for the sele,._-• tion of the panelists. These restrictions were necessary because of the counting tech-":'(':' nique used. ß . , . . Simple hair: one hair fiber emerges from a follicle orifice. Compound fibers: 2 or more ?.• :i fibers emerge from a follicular opening without a contiguous epidermal or stratum co '- neum bridge between them, as seen at 45-fold magnification. Single hair: a simple whose nearest neighbor is set at more than about 10 fiber diameters distance. Grouped. i: hairs: all compound hairs and those simple hairs which had neighbors not more than 3?'5: fiber diameters away. Site' the area occupied by a single hair or by grouped hairs. Conig ca.ia of ech vertex anterior and in front of the vertex posterior, according to the area designation of Moretri (17). On 8 of the panelists, the counting was repeated on the symmetrical right temporal area. ß ,: COUNTING METHOD Both counting and fiber collection were carried out in November and December, 1975. A template with a 1.00 cm z opening was placed on the head of the panelists i:?:. within 24 h of the last shampoo. With the help of a hooked needle, all fibers emerging • : jl from the skin within the 1.00 cm z opening were pulled through the frame while they were being viewed through a stereo microscope at 45-fold linear magnification. All the fibers were bent in one direction and counting started at the opposite end of the.i square, scanning along the skin line row by row. Each fiber counted was pulled over the?. opposite side of the opening with the hooked needle and held there by hand and All data and observations were called out by the observer and tape recorded for later .• transcription, because both hands of the observer were occupied during the process i:i:.: I' and the subject had to remain still. Only "terminal" fibers were counted. In our: , method, a fiber was classified as terminal if it was at least about 2 cm long (18) and was 5• : similar in diameter to the long fibers. The following characteristics were noted: total number of fibers, total number of sites, number of fibers within each single site, ing versus compounding for each fiber, relative geometric arrangement of the sites within the area, and the relative geometric arrangement of the fibers within sites.

FEMALE SCALP 221 FIBER COLLECTION FOR DIAMETER DETERMINATION Small areas, in the general location where fiber counting had been carried out, were randomly preselected. All fibers within this area were cut off at the skin line. About 30 fibers were collected from each individual. Compound and group 6bets were marked and kept separately from others to allow evaluation of intragroup and intracompound variations. The collected 6bets were cleaned with an ether rinse, and dried at room temperature. All further treatment and measurements were carried out at 70øF and 65 per cent RH. The fibers were individually cut to an exact length of 5.00 cm in a straightened configuration with the aid of a special instrument (19). The 5.00 cm length was cut starting about 1 cm from the original skin line of the fiber and, therefore, en- compassed the last 4 to 6 months of growth. The 5 cm long fiber segments were indi- vidually weighed on an electrobalance to the nearest 0.1 /xg. The idealized average cylindrical diameter was calculated from the weight of each fiber according to the following: D = 20 X/W/(3.14 x 1 x d) where D equals diameter in micrometers W equals weight in micrograms I equals length in centimeters = 5 and d equals density of fiber in g/cm a = 1.3. Correlations among different measured values were calculated according to a standard statistical program package supplied to our computer. RESULTS AND DISCUSSION HAIR COUNT A large proportion of the scalp fibers grow in groups. The fibers within a group are closely spaced, but the distance between neighboring groups is considerable, about 1 min. In order to minimize errors originating from the significant intergroup distance, the fibers were counted over a relatively large area--1 cmL This was in contrast to some earlier work (10, 11, 12, 13, 14, 15, 16), where the fiber number was determined in 2 mm squares. The results are shown in Table I. The age of the subjects ranged from 24 to 59, but only 3 participants were over 42. Since both age and racial origin have been reported to influence some of the measured characteristics (10, 11, 13, 16, 20, 21, 22), the average values are given both with and without the inclusion of the Chinese panelists. On the basis of the present work, it can- not be determined whether the differences seen between the 2 averages were due to racial or age factors. The number of fibers/cm 2 ranges from 95 to 295 with a mean of 211. Subject number 1--with the extremely low fiber count--shows signs of diffuse allopecia, associated with age, which was confirmed by photographs of her going back a few decades. The next 4 individuals with fiber counts under 160 fibers/cm 2 include 2 over 45 years of age (Chinese) and one of Spanish origin (number 4) with very dark hair. Number 3 has light brown hair and, according to her account, never had had more hair. The remainder of the panel had more than 190 fibers/cm 2. The correlation between decreasing hair count with increasing age is rather weak 0.601. This does not negate earlier findings that both hair and follicle numbers decrease with age (13, 16, 22). Our study did not include extreme ages, and even within the range, 85 per cent of