HOMO MILITAN'S 



ella pestis, while soon afterwards various investigators furnished proof 

 that plague is primarily a disease of rats and other rodents, with fleas 

 acting as the means by which the germs are transmitted from animal 

 to man. Since that time the war against bubonic plague has been 

 primarily a war against rats. 



It may here be remarked that plague epidemics, after all, have 

 spontaneously disappeared from Europe, while man has largely re- 

 mained passive. But then it must be pointed out that in Asiatic coun- 

 tries this disease continues to make victims on a large scale. In British 

 India alone more than 10 million people have died of plague during 

 the period 1 898-1 91 8. One may well shudder at the thought of what 

 might have happened in the densely populated island of Java if dur- 

 ing the past few decennia the 'Plague Control Service' had less ener- 

 getically fulfilled its task of rendering the homes of the Javanese pop- 

 ulation ratproof, and if Otten had not prophylactically treated 94 per 

 cent of the two million inhabitants of the Preanger district with the 

 live vaccine he had prepared. 



The pneumonic plague epidemic in Manchuria, characterized by 

 a very high mortality, and in which not the rat but the locally abun- 

 dant Siberian marmot ('tarbagan'), cherished for its fur, turned out 

 to be the source of the infection, caused a great stir in 19 10. A second 

 epidemic, which broke out ten years later, was successfully controlled 

 by the meanwhile established 'North Manchurian Plague Prevention 

 Service', notwithstanding the extremely difficult conditions under 

 which it had to function, thus causing the number of victims to be 

 greatly reduced. It must also be borne in mind that even in this cen- 

 tury occasional cases of bubonic plague have been detected in various 

 large harbour cities, such as Glasgow, Sydney, Melbourne, San Fran- 

 cisco, etc., and that over the period 191 3-1920 Van Loghem discov- 

 ered eight cases of rat plague aboard ships in Amsterdam harbour. 

 That in none of these instances an epidemic resulted must indubitably 

 be ascribed primarily to the effective measures instituted by Homo 

 militans. 



As a second example of an invisible form of life that even in recent 

 times, and with a good chance of success, has threatened human life 

 I mention influenza whose causative agent has turned out to be a 

 virus that only very recently has been isolated by Stanley and made 



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