PART 1.1 Conditions of the Soil Determine the Caw^ation of Cholera. 295 



theory " maintain, that an infinitesimal quantity of a choleraic discharge finding its 

 way into a river can multiply to such an extent as to be capable of infecting the popula- 

 tion of an entire city, a rapid and general diffusion of cholera would be readily 

 accounted for. If this were actually the case, however, it should follow that the progress 

 of cholera along the water-courses and in the direction of the current would be evident 

 to all. In that case, any outbreak of cholera which might occur in, the earlier part 

 of the year towards the north-west of the area under consideration, ought to be trace- 

 able week by week along the line of the streams and rivers which flow into the Granges 

 in the North-West Provinces, Oudh, Behar, and so on, in a direction towards the sea ; 

 but experience shows that, so far as the disease can be tracked in any definite direction-^ 

 that is to say, so far as the circumstance that the months of maximum cholera-prevalence 

 present a certain ill-defined, progressive arrangement along the stations in the Grangetic 

 plain, can be taken as indicative of the " direction '' taken by the disease — this direction 

 is precisely the reverse of that followed by the numerous streams and rivers ; cholera 

 attains its maximum in March and April towards the mouths of the Ganges, but not 

 till August at its sources. 



(3) In so far as the endemic area is concerned, there can be no doubt that the 

 soil-theory is more in accordance with the phenomena of the seasonal prevalence, of 

 cholera than any of the other theories previously considered. In regard to Upper 

 India the evidence is as ^yet defective, and detailed data are wanting on many points. 

 There are, however, certain important facts pointing very distinctly to the importance 

 of local soil-conditions in relation to cholera-prevalence in this area also. 



It was remarked, in one of the earlier chapters of this paper, that the nearer the 

 soil of a district in India approaches in character that constituting the lower portion 

 of the Grangetic plains, the greater is the likelihood that cholera will be found as an 

 endemic disease in it. It has been seen that the seasonal manifestation of cholera 

 changes gradually as we proceed up the river, the disease manifesting a tendency 

 to be deferred later and later in the year the farther the affluents of the Granges are 

 followed towards their sources, and the drier the climate and the soil become, so that 

 in the upper part of India and in the Central Provinces the maximum prevalence of 

 the disease occurs just at those periods when the soil-conditions most closely approach 

 those in Calcutta when in its driest state, ms., during and towards the end of the 

 rains, at which period alone the soil-conditions of the former are approximate to those 

 in Lower Bengal during the greater portion of the year. After bestowing the most 

 careful consideration on this matter, and after endeavouring to examine it in all its 

 phases, we have come to the conclusion that the theory which regards conditions of 

 the soil as essentially determining the production of the cause of cholera in a 

 locality, is much more in accordance with the phenomena of its seasonal prevalence 

 as manifested throughout the Bengal presidency than any of the other doctrines 

 appear to be. 



