JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 507 light of this knowledge, low-temperature setting was an obvious pos- sibility, especially as the first of the reactions, disulfide bond breakdown, can be carried out so easily by a multitude of reagents at ordinary temperatures. It was at this stage of the work that I first met the MacDonald brothers. They arrived at the University without warning, explained that, as makers of permanent waving machines, they had been in- terested in our work on high-temperature setting, and foresaw that we might develop low-temperature methods of setting. The advent of such methods would destroy their business as machine makers and they must, therefore, be the first to develop them. This was the beginning of a long period of collaboration, in which we were joined by Dr. N.H. Chamberlain, and by the end of 1934 the first patent applications for low-temperature permanent waving had been lodged in England. One of these was based on the use of reducing agents to promote disulfide bond breakdown, followed by treatment with oxidizing agents to reform disulfide bonds and thus fix the relaxed structure in its new configura- tion. This early emergence of processes for permanently waving hair in the cold is due principally to the remarkable foresight of William MacDonald, and it affords an excellent illustration of the advantages which accrue from having at least one person within an industry who is able and willing to take an interest in developments outside his own specialized field. But this is not the only, or even the main, reason for the respect in which I hold the MacDonald brothers. What this is will be clear from the following experience. During the early part of their career as makers of permanent waving machines, they had made many friend- ships among professional hairdressers, who were intended to have the exclusive use of the new methods of cold permanent waving. The production of "home-perm" outfits was never contemplated, and it was only when what is now one of the largest producers of such outfits sought a license to use the processes, that the MacDonalds realized the full ex- tent of the danger to which they had exposed the professional hairdresser. After some days' consideration, they informed the firm that they could not grant a license, although they realized that this could not prevent the marketing of home-perm outfits, since only the individual user could be charged with infringement, but it was impossible for them (the MacDonalds) to profit from what they then believed would be the distresses of their friends, the professional hairdressers. The matchless

5O8 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS integrity which compelled so quixotic a rejection of riches will, I hope, excuse my devoting so much of this address to those friends of earlier days. When the first of the cold permanent waving processes was invented, knowledge of the constitution and reactivity of keratin was still very primitive. It could be summarized in the statement that fibers like wool and hair consist of long, folded polypeptide chains with salt and cystinc linkages between them. During the past 35 years, however, there have been great advances in understanding, based on the use of new techniques such as electron microscopy and chromatographic methods of amino-acid analysis, but without any fundamental changes in the methods of permanent waving. These are still based on re- duction, followed by oxidation, and it is important to inquire why the new knowledge has found so little industrial application. For this purpose, different developments will be considered in turn. AMINO-ACID ANALYSIS The first complete amino-acid analyses of keratin became available in 1955 (1), but the knowledge was not as useful as was once expected, because earlier evidence that keratin is not homogeneous was reinforced by the results of electron microscope studies. The latter revealed the existence of ordered (crystalline) micro fibrils embedded in a disordered (amorphous) matrix, and during the past decade much effort has been given to the fractionation of keratin, identification of the histological origin of the fractions, and to their amino-acid analysis. The most usual method of experiment has been to oxidize cystinc cross linkages into cysteic acid side chains, to extract the oxidized keratin with dilute ammonia, and then fractionally precipitate the extracted proteins with acid. There is evidence to link the two main fractions with micro fibrils and matrix, and some of the differences in composition are given in Table I (2). The fact that the two fractions differ so greatly in content of cystine, lysine, and serine, all of which are now known to be involved in high- temperature setting reactions, is one of the reasons why early X-ray studies of fibers set at high temperatures showed such a difference in rate of response of the ordered and disordered regions. Because of this difference in rate of response, and also of rate of loss of set during relaxation in steam or boiling water, it became clear also that no exact understanding of the chemical mechanism of setting with different re- agents could be obtained from dimensional changes alone. It was