42 Observations Regarding Pettenkofer s T/ieory. [part i. 



enable one to have formed but most indefinite conclusions on the subject. Accustomed 

 as the Bavarian Health Officer has been for many years to much deep thinking 

 on the subject, it is frequently difficult for less trained intellects to follow his exact 

 meaning on all points, as the theory is by no means so simple that " he who runs 

 may read." 



During the last year a work* was issued by him embodying the result of the 

 labours of previous years, in which the views already advanced are maintained with even 

 a greater conviction of their truth than before. 



The main points in Pettenkofer's theory are — (1) there exists a specific cholera 

 poison, which (2) reaching the soil undergoes various stages of development, providing 

 (3) that a certain amount of moisture is present ; (4) should the ground not possess the 

 requisite amount of moisture, be either too dry or too wet when the poison is placed 

 therein, the latter will retain its vigour until the requisite conditions return ; but (5) 

 these having returned, it does not follow that an epidemic will forthwith break out, 

 unless (6) certain meteorological conditions are present (the precise nature of which is 

 unknown), and especially there must be (7) a predisposition to the disease in persons 

 coming within the area in which the poison is found. 



The reason why the period when cholera usually breaks out in the Upper Provinces 

 does not correspond with the period in which it is at its height in Calcutta and in 

 Lower Bengal generally, is, according to Dr. Pettenkofer, due to the fact that in the 

 former place the ground for the greater part of the year is too dry, there being no 

 rain, and the water being commonly many feet from the surface ; whereas in Lower 

 Bengal when the rains set in cholera ceases — the ground becomes too wet. Cholera 

 is worst in the latter when the water-level is at its lowest, namely, about April ; 

 whereas in the former cholera is at its worst when the water-level is rising or about 

 subsiding (August and September), so that, I presume, the Munich Professor would 

 explain the reason why cholera is endemic in Bengal, and only epidemic in the Upper 

 Provinces by the fact that the wet season is much shorter in* its duration than the dry, 

 consequently the conditions necessary for the development of the poison occur only 

 during short periods, whereas the same conditions affect Lower Bengal in a different 

 way, giving rise to short periods of exemption, instead of the short periods of attack, 

 consequently the inhabitants of the " Ditch" are more exempt from cholera when it 

 overflows with water. 



It must also be borne in mind that the local fall of rain is not in all cases the 

 only cause of variation in the height of subsoil water, for an adjoining river may rise 

 or fall, irrespective of local conditions, and perhaps give rise to an alteration in the 

 amount of moisture present in the soil. In a great number of instances, however, the 

 level of the water in a well adjoining a river is considerably above that of the river, 

 as a non-porous, clayey layer may dip towards it, thus confining the water to its bed. 



* "Boden und Grundwasser in ihren beziehungen zu Cholera und Typhus." Von Max v, Pettenkofer. 

 Miinchen, 1869. 



