4 QUATERCENTENARY STUDIES IN PATHOLOGY 



little understood, to be taught to any but technically-trained people. 

 But when Koch came, a note of hope rang round the world. He passed 

 through the fire of criticism, not scathless, but carrying with him his 

 cardinal fact — that where his bacillus was, there also was tuberculosis. 

 The word tuberculosis passed from the vagueness of speculative 

 pathology into the circle of positive science. It was henceforth to mean 

 something as definite as gunpowder, or oxygen, or steam. Forthwith, 

 tuberculosis became a doctrine that the lay mind could grasp. It could 

 be taught as easily as the multiplication table, and it could be shown to 

 be as practical. 



So far, well. But this alone, though it excited the hopes of the 

 world and simplified the duty of the administrator, would not have 

 secured the growing interest of the layman. To him a new germ may 

 be an interesting curiosity ; he will listen to tales about it ; he will take 

 pride in repeating its name. But he is nothing if not practical. If you 

 cannot do him some definite good, you will tire his interest and you will 

 provoke him to reaction. Fast on the heels of the new bacillus came 

 the suggestion that the disease due to it was no longer hopeless and 

 incurable. Then the whole world began to ask for a miracle. It seemed 

 for a time as if the miracle had happened and the diseased were to be 

 made whole. The heart sank when the signs failed. But the miracle 

 had indeed happened, although the revelation of it was looked for too 

 soon. Science on the one hand, and, on the other hand. Nature came, 

 once more, together, and the open-air treatment became a fact. Mean- 

 while, science pushed forward more and more intensively until new facts, 

 new methods, new habits of the organism revealed themselves, and now, 

 after all, the tuberculine cure of tuberculosis is no longer a dream of 

 possibilities, but a definitely established doctrine. The conditions are 

 not so simple as the natural feelings led us to imagine ; but they are not 

 so complex as to have baffled the patience of research. The day is here 

 when, not as a vague belief resting on unsolved mysteries, but as a 

 permissible deduction from ascertained fact, the forecast of the near 

 future may be — tuberculosis will be extirpated. 



So far, again, well. But in the popular mind there was another 

 obstacle. Biology, on the authority of great names, had left us with a 

 crude theory of inheritance. What could it profit that we isolated the 

 bacillus if the personal pedigree were bad ? Did we not hear tales of 



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