45« ANNUAL REPORT OF THE Off. Doc. 



vent this intercourse is to isolate the patients. This was most rig- 

 orously done in the Middle Ages by means of numerous leper-houses, 

 and the consequence was that leprosy, which had spread to an alarm- 

 ing extent, was completely stamped out in Central Europe. The 

 same method has been adopted quite recently in Norway, where 

 the segregatioo 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 in- 

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

 fresh cases kept regularly diminishing from year to year. Conse- 

 queotly 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 at the 

 root of the evil, and must not squander force in subordinate ineffec- 

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

 done, and what is about to be done against tuberp"losis really strikes 

 at the root of tuberculosis, so that it must sooner f later die. 



In order to answer this question it is necessary first and fore- 

 most to inquire how infection takes place in tuberculosis. Of 

 course, I presuppose that we understand 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 inhalatiou. As to the ques- 

 tion 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 dried, 

 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 produces phlegm and pus containing tubercle-bacilli, to the 

 formation of moist and dry particles (which, in virtue of their small- 

 ness, can keep floating a good while in the air), and finally to new 



