transmitted to the rabbit and relapsing fever to the mouse, the power of these preparations, as soon as manufactured, could be tested in the laboratory. The object, of course, was to find a substance which would kill the spirochetes without injury to the host. The result was the justly celebrated Ehrlich-Hata 606, chemically known as dioxydiamidoarsenobenzol, sometimes shortened to arsenobenzol, and, more recently, receiving the commercial name, Salvarsan. This substance in a single dose, 58 times smaller than the dosis tolerata (the largest dose which could be given with safety), cured definitely chicken spirillosis; a single small dose destroyed the spirolla of relapsing fever in infected mice, and a single injection of one seventh the dosis tolerata, caused the spirochete of syphilis to disappear completely from the experimental lesions of the rabbit within twenty-four hours. This last experience naturally aroused the hope of curing syphilis in man by a single injection given in the early stages. Such treatment, if successful, would supersede, or at least supplement, the empirical treatment by mercury which required a course of several years' treatment before a cure could be assured. The toxicity of the substance was, therefore, tested on dogs and then, to make sure it had no ill effects, on healthy men (assistants of Professor Alt), who volunteered for the purpose and finally the therapeutic effect was tried on relapsing fever in man. Iversen, of Eussia, to whom this work was entrusted, found that one injection completely cured relapsing fever in 90 per cent, of his patients. Finally the substance was used in the treatment of syphilis in man. The completeness and rapidity of the curative action have been astounding. The effect on the lesions of the primary and secondary stages is to cause them to heal or disappear promptly; the spirochetes can not be found after a few days and the effect is apparently one of complete sterilization. Thousands of reports in the medical press confirm the general beneficial effect of this remedy and testify to the absence of ill-effects when properly administered. Even though further experience may modify the present optimism, nothing can detract from the magnificent service by which Ehrlich and his pupils have benefited humanity and added to the glory of medical science by establishing the principle of specific chemotherapy. With a record of about a dozen drugs which can be used to cure or modify diseases caused by nearly a dozen different protozoa, chemotherapy offers promise of results which, with serumtherapy and vaccination in bacterial diseases, will sharply limit the ravages of the transmissible diseases of man and animals.
- (I.) The arsenic group: arsenious acid, atoxyl, acetylatoxyl, arsenophenylglycin and dioxydiamidoarsenobenzol. (II.) Azo-dyestuffs: trypan-red, trypanblue and trypan-violet. (III-) Basic triphenylmethan dyestuffs: parafuchsin, methyl-violet and pyronin.
- Nagana, surra, sleeping sickness, mal de Caderas, Texas fever, chicken spirillosis, relapsing fever and syphilis.