TEE COMBATING OF TUBERCULOSIS. 463 



tentionally exterminated the plague rapidly disappeared; whereas at 

 other places where too little attention had been paid to the rat plague 

 the pestilence continued. This connection between the human plague 

 and the rat plague was totally unknown before, so that no blame 

 attaches to those who devised the measures now in force against 

 the plague if the said measures have proved unavailing. It is 

 high time, however, that this enlarged knowledge of the etiology of the 

 plague should be utilized in international as well as in other traffic. As 

 the human plague is so dependent on the rat plague it is intelligible 

 that protective inoculation and the application of antitoxic serum have 

 had so little effect. A certain number of human beings may have been 

 saved from the disease by that, but the general spread of the pestilence 

 has not been hindered in the least. 



With cholera the case is essentially different; it may under certain 

 circumstances be transmitted directly from human beings to other 

 human beings, but its main and most dangerous propagator is water, 

 and therefore in the combating of cholera water is the first thing to be 

 considered. In Germany, where this principle has been acted on, we 

 have succeeded for four years in regularly exterminating the pestilence 

 (which was introduced again and again from the infected neighboring 

 countries) without any obstruction of traffic. 



Hydrophobia, too, is not void of instruction for us. Against this 

 disease the so-called protective inoculation proper has proved eminently 

 effective as a means of preventing the outbreak of the disease in per- 

 sons already infected, but of course such a measure can do nothing to 

 prevent infection itself. The only real way of combating this pestilence 

 is by compulsory muzzling. In this matter also we have had the most 

 satisfactory experience in Germany, but have at the same time seen 

 that the total extermination of the pestilence can be achieved only by 

 international measures, because hydrophobia, which can be very easily 

 and rapidly suppressed, is always introduced again year after year 

 from the neighboring countries. 



Permit me to mention only one other disease, because it is etiologi- 

 cally very closely akin to tuberculosis, and we can learn not a little 

 for the furtherance of our aims from its successful combating. I mean 

 leprosy. It is caused by a parasite which greatly resembles the tubercle 

 bacillus. Just like tuberculosis, it does not break out till long after 

 infection and its course is almost slower. It is transmitted only from 

 person to person, but only when they come into close contact, as in 

 small dwellings and bedrooms. In this disease, accordingly, immediate 

 transmission plays the main part; transmission by animals, water, or 

 the like is out of the question. The combative measures, accordingly, 

 must be directed against this close intercourse between the sick and 

 the healthy. The only way to prevent this intercourse is to isolate the 



