75 



as above related, there are doubtless many practising 

 physicians who cannot believe that tuberculosis is com- 

 municable. Why ? First, because clinical proof to that 

 effect is unsatisfactory ; a surgeon pricks his finger in 

 dressing a pyaemic patient, and in twenty-four hours has 

 a chill and local symptoms pointing unmistakably to 

 the source of infection ; a physician inspires the breath 

 of a struggling diphtheritic patient, and in three or four 

 days gives evidence that the disease was communicated. 

 Had tuberculosis ever been observed to occur in animals 

 so soon or so violently, were the introduction of tuber- 

 culous as well as of pyaemic and erysipelatous virus ac- 

 companied by chill, fever, and severe acute local inflam- 

 mation (it does seem to be so accompanied in gen- 

 eral acute miliary tuberculosis), there might be reason in 

 the objection that no absolute clinical proof has been 

 furnished. But even when the freshest of tuberculous 

 material is introduced into the most favorable soil, the 

 eye of a susceptible rabbit, two to four weeks elapse be- 

 fore the first local manifestation of infection, and further 

 weeks or months before the evidences of general tuber- 

 culosis are apparent ; there is, indeed, nothing in the 

 animal's history to indicate infection, the proof of which 

 consists merely in the conscious act of inoculation. An 

 observer who was not aware of this act, might honestly 

 believe that the infection which manifests itself weeks or 

 months later is spontaneous even autochthonous ; and 

 some physicians, because they see no transfer of tuber- 

 culous material (though opportunities enough for such 

 transfer are certainly given), because they see no strik- 

 ing symptoms to mark the hour or the day of infection^ 

 insist that no infection has occurred. 



A man may be shot in the presence of witnesses ; but 

 if we find a body with a bullet in thq heart, we are none 

 the less certain that this body, alive or dead, has been 

 shot, though no revolver nor human agent may be dis- 

 coverable. A man may be killed by the lightning which 

 dazzles all eyes ; but he is none the less killed if the 

 electricity be the invisible current of a powerful battery. 



