THE BACILLUS OF PLAGUE. 



AMONG the services rendered by bacteriology to 

 medicine, not the least is the discovery of the 

 micro-organisms which are the cause of two diseases that 



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have lately reappeared in epidemic form. Both influenza 

 and the plague, diseases well known to our forefathers, have 

 been proved to be of bacterial origin, and as the result a mass 

 of conflicting and contradictory evidence on the causation 

 of these diseases has been cleared away. 



Although the recent spread of the plague in China and 

 India has drawn the attention of most civilised governments 

 to the question of how the possible introduction of this dis- 

 ease into Europe may be prevented, it is worth noting that 

 during the last forty years from 1855-95 the plague has 

 appeared more than sixty times as large or small epidemics. 

 Mahe (1) has pointed out that most of these outbreaks have 

 occurred in Southern China, but on eighteen separate 

 occasions it has been seen in Persia, twenty-six times in 

 Turkey and five in Turkestan. One epidemic is recorded 

 in South-east Russia, while in India, especially in the 

 districts of Kumaon and Garwhal, the plague has appeared 

 at least six or seven times. A study of the outbreaks in 

 Marseilles in 1720, in Moscow in 1770, in Cairo and 

 Smyrna in 1834, together with the one so well described by 

 Russell in Aleppo during 1760-63, was until four years ago 

 the chief source of our knowledge of the causation, symptoms 

 and progress of the plague ; and although no material ad- 

 vance has been made in the clinical history of the disease, it 

 is interesting to recall some ideas which were current as to 

 its causation. " During the continuance of the epidemic 

 effect," writes an author fifty years ago (2), "a principle is 

 given off from the body which, if very concentrated and 

 pent up in confined and unwholesome situations, may 

 generate the disease, so that, though not originally con- 

 tagious, it may in this way by accumulation of animal 

 miasms be contagious ; and when the disease is communi- 



