THE STORY OF NINETEENTH-CENTURY SCIENCE 



new methods had made their way everywhere, revolu- 

 tionizing the practice of surgery, and practically banish- 

 ing from the earth maladies that hitherto had been the 

 terror of the surgeon and the opprobrium of his art. 

 And these bedside studies, conducted in the end by 

 thousands of men who had no knowledge of microscopy, 

 had a large share in establishing the general belief in 

 the causal relation that micro-organisms bear to disease, 

 which by about the year 1880 had taken possession of 

 the medical world. But they did more ; they brought 

 into equal prominence the idea that, the cause of a dis- 

 eased condition being known, it may be possible as 

 never before to grapple w r ith and eradicate that condi- 

 tion. 



The controversy over spontaneous generation, which, 

 thanks to Pasteur and Tyndall, had just been brought 

 to a termination, made it clear that no bacterium need 

 be feared where an antecedent bacterium had not found 

 lodgment ; Listerism in surgery had now shown how 

 much might be accomplished towards preventing the 

 access of germs to abraded surfaces of the body, and 

 destroying those that already had found lodgment 

 there. As yet, however, there was no inkling of a way 

 in which a corresponding onslaught might be made upon 

 those other germs which find their way into the animal 

 organism by way of the mouth and the nostrils, and which, 

 as was now clear, are the cause of those contagious diseases 

 which, first and last, claim so large a proportion of man- 

 kind for their victims. How such means might be 

 found now became the anxious thought of every im- 

 aginative physician, of every working micro- biologist. 



As it happened, the world was not kept long in sus- 

 pense. Almost before the proposition had taken shape 



