SPIRILLUM CHOLERA ASIATICS. 451 



possible modes of transmission in large institutions and 

 in ships. 



Hence it is undoubtedly possible, by rigid and properly 

 applied cleanliness, to exclude a very important portion 

 of the modes of transmission of the cholera contagium. 

 And I may refer to the marked influence an influence 

 which will be discussed more in detail afterwards 

 which is exercised on the spread of the disease by the 

 introduction of a good and plentiful supply of water, 

 and by proper arrangements for the prompt removal of 

 dejecta. 



Having thus arrived at certain definite ideas as to the The epidemic 

 mode of transmission of cholera to the individual, and cholera. * 

 as to the factors which come into play, ideas founded 

 partly on the study of the biological characters of the 

 comma bacilli and partly on the results of experience 

 with regard to cholera, we may attempt by the aid of the 

 same factors to explain also the mode of the peculiar 

 epidemic distribution of cholera. 



Cholera epidemics present a series of very striking Endemic 

 phenomena, and phenomena very difficult to explain. 

 We see that cholera is constantly present in an endemic 

 manner only in Lower Bengal ; in the rest of India, 

 and more especially in Europe, it occurs only at intervals 

 in the form of devastating epidemics, and then again 

 completely disappears from these regions. The starting 

 point of these epidemics must always be sought in Lower 

 Bengal ; from thence the disease is evidently carried 

 into other regions. From what has been said above, Transmission 

 it is evident that this transmission seldom occurs by any thesick! a 

 other materials than the fresh dejecta of the patients, 

 whether the disease be mild or severe. Hence the 

 disease can only be carried over long distances when a 

 patient passes over the whole distance very quickly, and 

 at the end of his journey still furnishes dejecta con- 

 taining bacilli, or when a continuous chain is formed, 



