The Fundamentals of Bacteriology. Charles Bradfield Morrey

      ROBERT KOCH

      Pollender, in 1849, and Davaine and Rayer, in 1850, independently observed small rod-like bodies in the blood of sheep and cattle which had died of splenic fever (anthrax). That Egyptian chlorosis, afterward identified with Old World “hookworm disease,” is caused by the Ankylostoma duodenale was shown by Greisinger in 1851. In the same year the Schistosomum hematobium was shown to be the cause of the “Bilharzia disease” by Bilharz. Küchenmeister discovered the tapeworm, Tænia solium, in 1852, Cohn, an infectious disease of flies due to a parasitic fungus (Empusa muscæ) in 1855, and Zenker showed the connection between trichinosis of pork (“measly pork”) and human trichinosis (1860) as indicated above. The organisms just mentioned are, of course, not bacteria, but these discoveries proved conclusively that living things of one kind or another, some large, most of them microscopic, could cause disease in other organisms and stimulated the search for other “living contagiums.” In 1863 Davaine, already mentioned, showed that anthrax could be transmitted from animal to animal by inoculation of blood, but only if the blood contained the minute rods which he believed to be the cause. Davaine later abandoned this belief because he transmitted the disease with old blood in which he could find no rods. It is now known that this was because the bacilli were in the “spore” form which Davaine did not recognize. He thus missed the definite proof of the bacterial nature of anthrax because he was not familiar with the life history of the organism which was worked out by Koch thirteen years later. In 1865 Villemin repeatedly caused tuberculosis in rabbits by subcutaneous injection of tuberculous material and showed that this disease must be infectious also. In the same year Lord Lister introduced antiseptic methods in surgery. He believed that wound infections were due to microörganisms getting in from the air, the surgeon’s fingers, etc., and without proving this, he used carbolic acid to kill these germs and prevent the infection. His pioneer experiments made modern surgery possible. In this year also, Pasteur was sent to investigate a disease, Pebrine, which was destroying the silkworms in Southern France. He showed the cause to be a protozoan which had been seen previously by Cornalia and described by Nägeli under the name Nosema bombycis and devised preventive measures. This was the first infectious disease shown to be due to a protozoan. In 1866 Rindfleisch observed small pin-point-like bodies in the heart muscle of persons who had died of wound infection. Klebs, in 1870–71, published descriptions and names of organisms he had found in the material from similar wounds, though he did not establish their causal relation. Bollinger, in 1872, discovered the spores of anthrax and explained the persistence of the disease in certain districts as due to the resistant spores. In 1873 Obermeier observed in the blood of patients suffering from recurrent fever long, flexible spiral organisms which have been named Spirochæta obermeieri. Lösch ascribed tropical dysentery to an ameba, named by him Amœba coli, in 1875. Finally, Koch, in 1876, isolated the anthrax bacillus, worked out the life history of the organism and reproduced the disease by the injection of pure cultures and recovered the organism from the inoculated animals, thus establishing beyond reasonable doubt its causal relationship to the disease. This was the first instance of a bacterium proved to be the cause of a disease in animals. Pasteur, working on the disease at the same time, confirmed all of Koch’s findings, though his results were published the next year, 1877. Bollinger determined that the Actinomyces bovis (Streptothrix bovis) is the cause of actinomycosis in cattle in 1877. Woronin in the same year discovered a protozoan (Plasmodiophora brassicæ) to be the cause of a disease in cabbage, the first proved instance of a unicellular animal causing a disease in a plant. In 1878 Koch published his researches on wound infection in which he showed beyond question that microörganisms are the cause of this condition, though Pasteur in 1837, had suggested the same thing and Lister had acted on the theory in preventing infection.

      These discoveries, especially those of Koch, immediately attracted world-wide attention and stimulated a host of workers, so that within the next ten years most of the bacteria which produce disease in men and animals were isolated and described. It is well to remember that the first specific disease of man proved to be caused by a bacterium was tuberculosis, by Koch in 1882.

      Progress was greatly assisted by the introduction of anilin dyes as suitable stains for organisms by Weigert in 1877, by Koch’s application of special technic and gelatin cultures for isolation and study, 1881, and the great improvements in the microscope by Prof. Abbé, of Jena.

      Laveran’s discovery of the malarial parasite in 1880 turned attention to protozoa as the causes of disease and led to the discovery of the various piroplasmoses and trypanosomiases in man and the lower animals.

      Pasteur’s protective inoculations in chicken cholera and anthrax directed attention to the possibility of using bacteria or their products as a specific protective or curative means against particular diseases. This finally led to the discovery of diphtheria antitoxin by Behring, and independently by Roux, in 1890, a discovery which opened up the wide field of immunity which is so persistently cultivated at the present time.

      PLATE IV