464 POPULAR SCIENCE MONTHLY. 



patients. This was most rigorously done in the Middle Ages by means 

 of numerous leper-houses, and the consequence was that leprosy, which 

 had spread to an alarming extent, was completely stamped out in 

 Central Europe. The same method has been adopted quite recently 

 in Norway, where the segregation of lepers has been ordered by a special 

 law. But it is extremely interesting to see how this law is carried out. 

 It has been found that it is not at all necessary to execute it strictly, 

 for the segregation of only the worst cases, and even of only a part of 

 these, sufficed to produce a diminution of leprosy. Only so many infec- 

 tious cases had to be sent to the leper-houses that the number of fresh 

 cases kept regularly diminishing from year to year. Consequently the 

 stamping-out of the disease has lasted much longer than it would have 

 lasted if every leper had been inexorably consigned to a leper-house, as 

 in the Middle Ages, but in this way, too, the same purpose is gained, 

 slowly indeed, but without any harshness. 



These examples may suffice to show what I am driving at, which 

 is to point out that in combating pestilences we must strike the root 

 of the evil and must not squander force in subordinate ineffective 

 measures. Now the question is whether what has hitherto been done 

 and what is about to be done against tuberculosis really strikes the root 

 of tuberculosis so that it must sooner or later die. In order to answer 

 this question it is necessary first and foremost to inquire how infection 

 takes place in tuberculosis. Of course, I presuppose that we under- 

 stand by tuberculosis only those morbid conditions which are caused 

 by the tubercle bacillus. In by far the majority of cases of tuberculosis 

 the disease has its seat in the lungs, and has also begun there. From 

 this fact it is justly concluded that the germs of the disease — i. e., the 

 tubercle bacilli — must have got into the lungs by inhalation. As to the 

 question where the inhaled tubercle bacilli have come from, there is 

 also no doubt. On the contrary, we know with certainty that they get 

 into the air with the sputum of consumptive patients. This sputum, 

 especially in advanced stages of the disease, almost always contains 

 tubercle bacilli, sometimes in incredible quantities. By coughing and 

 even speaking it is flung into the air in little drops — i. e., in a moist 

 condition — and can at once infect persons who happen to be near the 

 coughers. But then it may also be pulverized when dry, in the linen or 

 on the floor for instance, and get into the air in the form of dust. In 

 this manner a complete circle, a so-called circulus vitiosus, has been 

 formed for the process of infection from the diseased lung, which pro- 

 duces phlegm and pus containing tubercle bacilli, to the formation of 

 moist and dry particles (which in virtue of their smallness can keep 

 floating a good while in the air), and finally to new infection if par- 

 ticles penetrate with the air into a healthy lung and originate the 

 disease anew. But the tubercle bacilli may get to other organs of the 



