Page:Popular Science Monthly Volume 41.djvu/639

Rh tuberculosis is an infectious disease, was contained in Koch's original memoir announcing his discovery. Investigations made since have fully confirmed Koch's conclusions in all important particulars. In order to show you the interest taken by bacteriologists and pathologists in all that relates to the tubercle bacillus and the effects of its pathogenic action, I have referred to the Jahresbericht of Baumgarten, for the year 1890, which gives abstracts of all original memoirs in this field of research. The total number of papers referred to, published during the year mentioned, is one hundred and thirty-five. By far the greater number are published in German and French journals, but the literature includes a certain number of memoirs published in Russia, in Italy, in Hungary, in Sweden, and in the United States.

Another important discovery, made in 1882, is that of the bacillus of glanders, by Löffler and Schutz.

Koch published his discovery of the cholera spirillum ("comma bacillus") in 1884.

The same year (1884) Löffler discovered the diphtheria bacillus. Subsequent researches have not only established the etiological relation of this bacillus to the disease known as diphtheria, but have given us an exact knowledge of its biological characters and pathogenic action, as tested upon lower animals.

The tetanus bacillus was discovered in 1884 by Nicolaier, a student in the laboratory of Prof. Fliigge, of Gottingen. That this bacillus is the cause of tetanus in man has been demonstrated by the subsequent researches of numerous investigators.

So far as human pathology is concerned, no important pathogenic micro-organism has been discovered since the date last mentioned (1884) until the present year. After numerous unsuccessful researches by competent bacteriologists, a bacillus has been discovered by Pfeiffer, of Berlin, and independently by Canon, which there is good reason to believe is the specific cause of epidemic influenza.

"We have, also, a recent announcement, by Canon, of the discovery of a minute bacillus in the blood of patients suffering with measles, but the etiological relation of this bacillus has not been established, and additional researches will be required before we can properly estimate the value of Canon's alleged discovery.

The brief historical review which we have made shows that the etiology of a considerable number of infectious diseases has been determined by the researches of bacteriologists, but it also shows that other important diseases of this class are not included in this list.

Up to the present date no satisfactory demonstration of the specific infectious agent has been made in any one of the eruptive fevers; and in yellow fever, my own extended researches have