+The Action of Salvarsan.+--It will be recalled that Ehrlich planned salvarsan to kill the germs of syphilis, just as quinin kills the germs of malaria. It was intended that when the drug entered the blood it should be carried to every part of the body, and fastening itself on the spirochetes, kill them without hurting the body. This is seemingly exactly what the drug does, and it does it so well that within twenty-four hours after a dose of it is given into the blood there is not a living germ of syphilis, apparently, in any sore on the body. If the same thing happened in all the out-of-the-way corners of the body, the cure would be complete. The natural result of removing the cause of the disease in this fashion is that the sores produced by it heal up. They heal with a speed and completeness that is an even greater marvel than the action of mercury. The more superficial the eruption, the quicker it vanishes, so that in the course of a few days all evidence of the disease may disappear. This is especially true of the grayish patches in the mouth and about the genitals, which have already been described as the most dangerously contagious lesions of syphilis. It is evident, therefore, that to give salvarsan in a case of contagious syphilis is to do away with the risk of spreading the disease in the quickest and most effective fashion. It is as if a person with scarlet fever could be dipped in a disinfecting bath and then turned loose in the community without the slightest danger of his infecting others. How much scarlet fever would there be if every case of the disease could be treated in this way? There would be as little of it as there now is of smallpox, compared to the wholesale plagues of that disease which used to kill off the population of whole towns and counties in the old days. If we could head off the crops of contagious sores in every syphilitic by the use of "606," syphilis in the same way would take a long step toward its disappearance. It is not a question, in this connection, of curing the disease with salvarsan, but of preventing its spread, and in doing that, salvarsan is one of the things we have been looking for for centuries.