28 PATHOGENIC BACTERIA. 



only been perfected by workers as it has been found nec- 

 essary from time to time to comply in the most minute 

 detail with Henle's conditions, and as, one point being 

 carried, it was found necessary to advance on others. 

 The first of these was that a specific organism should 

 always be associated with the disease under consideration. 

 As such presence, however, might be accidental, these 

 organisms were not only to be found in pus, etc. , but actu- 

 ally in the living body. As they might be, even then, 

 merely parasitic, and not associated directly with the 

 causation of the disease, it would be necessary to isolate 

 the germs, the contagium organisms, and the contagium 

 fluids, and to experiment with these separately with 

 special reference to their power of producing similar 

 diseases in other animals. We now know that it has 

 only been by strict compliance with all these conditions, 

 again postulated by Koch, that the most brilliant scien- 

 tific observers and experimentalists in Germany, France, 

 England, [and America] have been able to determine 

 the causal connection between micro-organisms and 

 disease." 1 



The refined methods of Pasteur, but more especially 

 of Koch, by making possible the fulfilment of the pos- 

 tulates of Henle caused an enormous increase in the 

 rapidity with which data upon disease-germs were gath- 

 ered. Almost within a decade the causes of the most 

 important specific diseases were isolated and cultivated. 



In 1879, Hausen announced the discovery of bacilli in 

 the cells of leprous nodules. The same year Neisser 

 discovered the gonococcus to be specific for gonorrhea. 



In 1880 the bacillus of typhoid fever was first observed 

 by Eberth, and independently by Koch. 



In 1880, Pasteur published his work upon "chicken- 

 cholera." In the same year Sternberg described the 

 pneumococcus, calling it the micrococcus Pasteuri. 



In 1882, Koch made himself immortal by his discov- 

 ery of and work upon the tubercle bacillus. The same 



1 Woodhead : Bacteria and their Products, p. 65. 



