It was to be anticipated that Dr. Koch's discovery of the tubercle bacillus would lead him on to the discovery of a cure for tuberculosis. Very naturally his thought on this subject was borne in the direction of inoculation. That method had been used by Pasteur and by himself in the case of other infectious diseases. Why should it not be employed in consumption? If the "domestication," so-called, of the virus of splenic fever and the use of the modified poison as an antiseptic preventive of the disease was successful, as it had been proved to be, why should this not be done with the attenuated virus of consumption?
The last five years of the ninth decade were spent by Dr. Koch in experimentation on this subject. He found that the tubercular poison might be treated in the same manner as the poison of other infectious diseases. He experimented with methods for domesticating the bacillus of consumption, and reached successful results. On the fourteenth of November, 1890, he published in a German medical magazine at Berlin a communication on a possible remedy for tuberculosis. He had prepared a sort of lymph suitable for hypodermic injection, and with this had experimented on a form of _external_ tuberculosis called lupus. This disease is a consumption of the skin and adjacent tissues. It is a malady almost as dreadful as consumption of the lungs, but is by no means frequent in its occurrence. It is found only at rare intervals by the medical practitioner.
Dr. Koch had demonstrated that lupus is a true tuberculosis--that the germ which produces it is the same bacillus which produces consumption of the lungs. He accordingly directed his effort to cases of lupus, treating the patients with hypodermic injections which he had prepared from the modified form of the tubercular poison. He was successful in the treatment, and was able to announce, to the joy of the world, that he had discovered a cure for lupus; and the announcement went so far as to express a belief in the salutary character of the remedy in the treatment of consumption of the lungs.
Dr. Koch, however, with the usual caution of the true men of science, did not announce his tuberculin, or lymph, as a cure for pulmonary consumption. He did not even declare that it was positively a remedy for the other forms of tuberculosis, but did announce his cure of cases of lupus by the agent which he had prepared. The world, after its manner, leaped at conclusions, and the newspapers of two continents, in their usual office of disseminating ignorance, trumpeted Koch's discovery as the end of tubercular consumption.