JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS with their other effects on the epidermal derivatives, I would expect them to promote the catabolic phase, of which keratinization is part, at the expense of the anabolic phase of cell activity. Mercer et al (34) suggest that inter- cellular adhesion in the mid-bulb region is limited to small localized areas, but higher up the follicle there is a dense amorphous adhesive cement between the cells, and this cement is essential to keratinization. I would not care to speculate whether this process is a point where the oestrogen might act, but the question could be investigated experimentally. DR. E. LuDwiG: Are you able, on the basis of your observations on various animal species, to confirm that the hair follicle reacts to damage only in the following two ways: Firstly, by retiring in the telogen stage, in which instance a perfectly normal club hair results, and secondly, by disintegration in which case the result is a distrophic broken hair shed about 10 to 14 days after injury. THE LECTURER: In our studies we have not been able to bring about a disintegration of the follicle, but we have carried out a number of studies on the reaction of the follicle to plucking of the hair. It is well known that plucking of a hair in the telogen phase initiates a new cycle of activity. In the rat, if a hair is plucked when it is in the growing phase, the cycle appears to be shortened a premature catagen is induced, and this is consistent with your observation in man. The result appears to be evidence against the hypothesis that during the growing phase there is a build up of an inhibitor within the follicle if that hypothesis were true one would expect the follicle to produce a full-length hair after each plucking. I thus confirm your first point, but as to disintegration of the follicle--we have not observed it. MR. A. FOSTER: It has not been made clear whether the changes that take place in phasing are permanent or whether they only follow the next wave after the graft. Are they permanent with successive waves ? THE LECTURER: This question is slightly complicated. If the follicles are put out of phase by an operative procedure, such as grafting or plucking, they remain in this state for a long time. But it is possible that they gradually alter their phasing. Our animals have only a limited life so that it is difficult to give a categoric answer from our present evidence. MRS. H. BUTLER: I believe I understood you to say that adding oestrogen increased the rate of keratinization, but delayed the falling out of the hair. Could you clarify that please ? THE LECTURER: There are two quite different effects of oestrogens. One is the effect on the timing of the cycle itself in all our experiments it was clear that oestrogens both delay the initiation of follicular activity and the shedding of club hairs. Secondly, there is the effect on the growing hair. In female rats the hair is not quite as long as in males, but after removal of the

THE ACTIVITY OF THE HAIR FOLLICLE 457 ovaries, the hair, when next replaced, grows to the same length as in males. I suggested that oestrogen might accelerate the breakdown processes of the cell, of which keratinization is part, thus shortening the synthetic phase with the result that less hair is actually produced. MR. R. L. DAvIEs: Do you know anything about the phenomena where hairs sometimes occur in small groups, usually of three ? Have you any information why this particular grouping takes place, and on the fall-out pattern in such groups ? T•E LECTURER: Are you referring to the human scalp, or do you mean throughout the mammals ? MR. R. L. DAvIEs: The human wrist, at least on my wrist they certainly occur in groups of three. THE LECTURER: The whole question of follicular pattern is a complicated one. It is a consequence of embryonic development which in turn may be related to evolutionary history. I do not know whether there is any con- sistent pattern of replacement within each group. •/[R. C. ]BEDEMAN: You state that follicles do not seem to be lost in the pro- cess of balding, but that they regress. Can you enlarge on this somewhat ? ThE LECZURER: According to Hamilton (31), the density of follicles remains similar in bald and non-bald areas. In baldness the follicles do not actually seal up, but they regress to produce only a fine veilus hair. In normal, patterned baldness the proportions of the follicle remain unchanged the follicle gets much smaller but the volumes of the matrix and of the dermal papilla are proportionally reduced. On the other hand, in alopecia areata which is reversible in some circumstances, the papilla does not shrink as greatly as the matrix. Both types of follicle produce cosmetically useless hairs. MR. J. K. HEm): In answer to Mr. Davies I would like to state that we have noted, in the human scalp, the occurrence of some hairs in groups of up to 4 hairs. We did not determine whether multiple follicles were involved but this is likely since it was often noted that all the hairs were actively growing, though not necessarily at the same rate. The number of hairs in these groups was characteristic of the individual, and thus it was often possible to identify the particular person by examining photographs (x 10) of the scalp. THE LECTURER: The study of the actual course of balding which Mr. Herd and his associates have been carrying out, is breaking some new ground. I think most of the statements that are made about bald heads refer to areas already bald. The transition from the normal follicle, which produces long terminal hair, to the degenerate follicle which produces veilus is worthy of investigation.