42 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS for resting follicles and at a lower dose. In the mouse in which the same follicles may have a resting element with a club hair together witk a growing element with a bulb, depila• ion by X-rays of each of these hairs is independent and characteristic. This indicates that the effect is on the epithelium and not dependent on vasculartry. "EFFECTS OF IONISING RADIATION ON HAIR ROOTS OF THE HUMAN SCALP" EUGEr•E J. VXN SCOTT The direct effect of tonising radiation on hair follicles can be studied by microscopic examination of unstained roots of hairs extracted from the irradiated scalp. Changes in the hair root are detectable as early as two days following irradiation and become progressively more manifest thereafter. These changes are confined to growing hair follicles and consist of a characteristic progressive atrophy of the entire hair bulb, which begins in the matrix portion. At the end of 10-14 days complete disintegration of the bulb occurs, leaving a severely tapered proximal tip of extracted hairs. Such hairs fall out at the end of three weeks. The roots of a proportionately few hairs recover during the first week, assume a structurally normal bulb, and con- tinue to prodace a hair the hair shaft has a smaller diameter in a demar- cared zone which can be identified, as judged by its distance from the bulb, as that portion of hair shaft produced during the time of radiation. Calculation of the percentage of growing hairs demonstrating morphological effects of irradiation may be done by examination of one hundred or more hairs manually extracted from areas of scalp exposed to different doses of radiation. Such examinations, repeated at intervals during the week following irradia- tion, reveal that the percentage of hairs showing changes increases linearly in relation to both time and to the dose of irradiation to which the hair roots were exposed. "CHANGES IN HAIR ROOTS OF THE HUMAN SCALP FOLLOWING THERAPY WITH A FOLIC ACID ANTAGONIST" EUGENE J. VAN SCOTT The loss of scalp hair following amethopterin (Methotrexate), unlike that due to either ionising radiation or systemic diseases, is due to a breakage of the hair shaft and not to a falling out "by the roots." Microscopic examination of unstained roots of hairs pulled from the scalps of patients receiving therapeutic doses of amethopterin reveals a transient but reversible injury to the hair bulb. There is a decrease in the diameter of the hair formed during the time of administration of the drug.

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.