ABSTRACTS OF PAPERS ON THE BIOLOGY OF HAIR GROWTH 43 When the administration of the drug is stopped the bulb recovers completely and again produces a hair shaft of normal diameter. As a result, hairs from patients who have received amethopterin have zones of constrictions. The degree of constriction corresponds to the dose of drugs employed and may be so severe that the shaft breaks at this point when the hair is pulled or even when it is combed or casually manipulated. "l%IUTRITIONAL FACTORS INFLUENCING THE GROWTH OF HAIR" M. L. RYDER Wool Industries Research •l ssociation, Leeds 6, England. The amount and quality of food governs the weight of wool a sheep grows, and a poor diet reduces the length and diameter of the wool fibres. The addition of both protein and carbohydrate to the diet increases wool production. Carbohydrate is needed to provide energy for protein utilisation, apart from releasing protein for wool growth. Carbohydrate is also essential for mitosis, and the importance of glycogen in the follicle has been amply demonstrated. Cystine or methionine are essential for hair growth in many animals but sheep can readily' synthesise cystine from sulphate. B vitamins are necessary agents for the growth of hair pan•othenic acid seems to be associated with the utilisation of copper. Deficiency of copper causes loss of pigment, and in wool, a loss of crimp. Copper is thought to catalyse the oxidation of to --S--S-- groups but it has not been possible to detect copper in the follicle either histochemically or with the use of Cu -64. It is doubtful, how- ever, if any of the dietary deficiencies reported to cause impaired growth are really specific. Loss of hair due to poor diet does not seem to be by the formation of "brush ends," but apart from the thinning of the fibre there is a reduction in breaking strength. A poor diet retards follicle development in young animals, but it is doubtful if there is a permanent effect. The larger the papilla is, the more blood vessels it contains and the greater is the diameter of the fibre. Variations in diameter of the fibre seem to be associated with the number of vessels in the dermal papilla as well as variations in the density of the surrounding net of vessels. A large follicle has an extensive supply because it is large it is not this that makes it large. Within a few minutes after the injection of cystine labelled with S -85. radioactive particles appeared first immediately above the bulb, suggesting an entry at this level h'om the surrounding capillary net rather than through the papilla vessels. Soon after an injection of glucose labelled with C -• the activity is in the bulb and not above it. There seems to be a rapid turnover of cystine in the body, but small amounts still enter the follicle up to 3 weeks afterwards after its injection.

44 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS "AGE, SEX AND GENETIC FACTORS IN THE REGULATION O• HAIR GROWTH IN 1V•AN: A COMPARISON OF CAUCASIAN AND JAPANESE POPULATIONS" JA•s B. D•pt. of .tintomy, Stat• Uniw•sity of N•w York, Coll•g• of Medicin• at N.Y. City, Brooklyn, New Yor•. Techniques have been devised • to provide repeatable quantitative measure- ments of hairs and their rate of growth in certain regions of the body. Using these methods, data have been obt•ned for each sex throughout the life span in Caucasian and Japanese populations. The standards constructed from these values can serve to assess some aspects of physiologic age, and to study endocrine status. They will also be valuable in gaining further under- standing of the nature and interdependence of endocrine, ageing, genetic, environmental and other regulatory factors. Beard growth, in Caucasian as compared with Japanese males, was found to be considerably greater and values reached a peak at an earlier age. This was shown by measurements of weight of hair grown per day, and was associated with higher values in Caucasians for area of skin with coarse hairs and for number of such hair per sq. cm. of a standardised region of the cheek. In a large series of Japanese females no instance of facial hirsutism was found in contrast to the high incidence reported for Caucasian women. Males of both ethnic groups had similar values for the mean diameter of coarse hairs and of their component parts and for the percentage of grey hairs with advancing age. Growth of axillary hair was also more pronounced in Caucasian than in Japanese males of comparable sex and age. The disparity between the two ethnic groups in values for axillary hair was even greater in females than in males. These data for beard and axillary hair are in the same direction and extend previous reports of greater tendencies on the part of Caucasian males to develop coarse hairs on the external ears, to become bald and to develop ache. As a rule some of the late sequelae of sexual maturation were among those which tended to occur more frequently, and to progress further in Caucasians than in Japanese. This principle seems to apply to the areas with coarse hairs in the axilla and beard as well as to the severe forms of common baldness, and it may apply to ache. Secondary sex characters and certain sex-differing pathologic states failed to develop in men who did not mature sexually. The degree to which maintenance of these conditions, once fully developed, depended upon gonadal secretions, differed among the items studied these, listed in decreas- ing order of dependence, a• e the axillary hair, beard, and common baldness. Under ordinary conditions these traits are dependent upon gonadal secretions for development, and in some instances for maintenance, but this