1955 SEMINAR DISCUSSION 279 tion of asparagus no change whatever of the characteristic odor was noticeable. To Conrad's questions: While the surface lipids of normal human skin contain about 5 to 10 per cent squalene, there are characteristic species differences in wool fat, for example, squalene being absent or occurring only in traces (Sobel, Mac- Kenna, Wheatley and Wormall Rothman and Nicolaides). The species differences resemble those which exist in the fatty acid contents of skin fat from different species. Squalene is a physiologic precursor of cholesterol. The squalene content of human hair fat shows a three- to fourfold increase after puberty, whereas the cholesterol concentration declines by just as much (Rothman and Nicolaides). Considerably more cholesterol is pres- ent in the lipids on the stratum corneum than in "native" sebum. It appears possible that the conversion of squalene into cholesterol indirectly promotes the formation of the unsaturated fatty acids largely responsible for "body odor." To Lyon's remark: In support of Lyon, I should on this occasion re-emphasize the great shortcoming which obviates a satisfactory answer to the present question and to many other questions in this field, in that we are practically unable to obtain pure specimens from each of the different potential sources' of the materials in question. As yet, we cannot insert a catheter into the duct of a sebacesus gland and despite the solitary report by Japanese investigators of successful catheterization of an eccrine sweat duct, we generally are still unable to collect the unadulterated products of any of the skin glands. Many tedious attempts on our part (New York Skin and Cancer Unit) have failed thus far. Moreover, I cannot conceive of apocrine sweat being collected in a capillary placed into a hair follicle or directly on the skin sur- face without any admixture of sebaceous matter. Present knowledge indicates that most of the fatty acids encountered on the skin surface are not of glandular origin but formed externally by enzymatic action of the microbial flora. To Malkinson's question: As was aptly demonstrated by Marchionini and Cerrutti [Arch. Der- mato/u. Syphilis, 166, 354 (1932)], osmidrosis or "bromidrosis" of the feet essentially results from impaired evaporation and stagnation of eccrine sweat, with consequent swelling, bacterial infection and decomposition of keratin. The pH of the affected skin surface shows a shift toward alkalin- ity which in turn further enhances the growth of micro6rganisms. The odorous substances apparently are derived from the hydrated keratin by enzymatic action of the microbial flora. Although proper hygiene is useful also in bromhidrosis of the feet, often repeated washings may be less expedient than in the axillae because keratin swelling is promoted.

:280 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS For obvious reasons, the toe webs and any other part of the foot where sweat evaporation is impeded are the sites of predilection to develop the fetid odor. Certain deformities, moreover, such as superimposed toes or toes which are tightly squeezed together or the missing arch of the soles in subjects with a high degree of flat feet, frequently cause or aggravate sweat stagnation and malodorous decomposition. In subjects of this kind, the bromhidrosis is promptly alleviated by correction of the anatomical anomaly. When sweating is excessive a priori and/or the native sweat's composi- tion, e.g., by a high pH, favors the changes leading to keratin swelling and bacterial growth, the bromhidrosis is linked to these "idiopathic" factors. To Klarmann's discussion: I fully subscribe to what Klarmann has said but should add that clinical trials we thus far carried out with cationic wetting agents, notably with different dilutions of Zephiran chloride in water, were rather disappointing, inasmuch as skin irritation sooner or later ensued, preventing continua- tion of the applications. Concerning the action of exchange resins, preliminary assays appear pertinent in which we (New York Skin and Cancer Unit) applied such resins .externally in powdered form, or incorporated in creams or lotions and observed definite changes in pH. as well as a relatively frequent reduction of sweating in response to these applications. While the anion exchange resins produced an increase in pH, the cation exchange resins caused a decrease which was much more pronounced in the axillary vaults than in all other skin areas under study. The cation exchange resins were con- siderably more effective in diminishing sweat delivery than were the anion exchangers. The powders were the most and the creams the least effective. Despite the early stage of investigation of these agents in the axillary vaults, I feel that their effect is quite complex. To Fredell's paper: In full agreement with Fredell, we frequently observed a transient pro- vocatory effect of single applications of creams containing aluminum salts, prior to manifestation of reduced sweat delivery. We regarded the pro- vocatory action as an effect of the ointment base and as related to the increased outpouring observed in response to topical application of lanolin by Unna and later by Pollitzer, Rothman, O'Brien and ourselves.