the median number of rubs. This, however, is easily explained. It means merely that the more susceptible patients develop mercurialism, not only after a smaller number of rubs, but of a type that progresses in sever¬ ity much more rapidly than with the less susceptible patients.The* results of all the series show that the average susceptibility is strikingly uniform in different series, if a sufficient number of patients is observed. They show also, however, that the susceptibility of a consid¬ erable number of individual patients differs widely from this average. If we give to the average a latitude as wide as from eleven to nineteen rubs, we find, in 112 observations (combining all the series), that fifty-five patients, or 49.1 per cent., are within this range; twenty-five patients, or 22.3 per cent., require less than eleven rubs (from five to ten) ; thirty-two patients, or 28.6 per cent., require more than nineteen rubs (from twenty to thirty-eight) ; i. e., about half of the patients require from eleven to nineteen rubs ; about a fourth require less and another fourth more than this number. Among the factors that might be concerned in these variations of susceptibility may be named:A. Locally: (1) Condition of the teeth.(2) Oral hygiene during administration. B. Systemically : (3) Idiosyncrasy and resistance. C. Excretion : (4) Renal efficiency. D. Absorption: (5) Efficiency of inunction.(6) Condition of the skin. Differences in the energy of inunction and in the oral hygiene, which play a large rôle ordinarily, prob¬ ably play a relatively small part in this series, since precautions were taken to secure uniformity in these respects. No systematic attempt was made to distin¬ guish between the other causes, but we were rather impressed with the importance of the condition of the skin as a factor in absorption. Thus, in the present series, there were five patients who had extensive, gen¬ eralized, miliary, papular syphilids : all were salivated by few rubs (7, 7, 9, 10 and 11 ; the 9 rub patient "old style," the others with improved technic). Another congenitally syphilitic patient had an ichtbyosis ; mer¬ curial effects started early, and severe salivation resulted after fifteen rubs ("improved technic"). When the skin is diseased, it may be supposed that the oint¬ ment may obtain direct access to the stratum mucosum through fissures. We have also gained the impression (but have not sufficient data for a decisive judgment) that patients whose skin is abnormally dry tend to be hypersusceptible, perhaps because such skins are more easily fissured, or perhaps because the ointment can be rubbed more easily into the ducts when the glands are not actively secreting. This would be somewhat analogous to the observation of McConnell a that indi¬ viduals with a very dry skin were more prone to indus¬ trial dermatoses. His observations were made in studying dermatoses due to cutting oils, and the erup¬ tions seen in printers. He explains this phenomenon as due to the fact that the epidermal cells of patients with a dry...
