446 SPIRILLUM CHOLERA ASIATICS. 



we must, however, assume that in the case of the water 

 ordinarily used for drinking and other purposes multi- 

 plication of the comma hacilli never occurs, and that there- 

 fore they can only he present in wells for a relatively 

 short time. (Compare the investigations by Bolton in 

 the Zeitschrift fur Hygiene, vol. i.) In the case ol 

 stagnant water, however, in the bilge water of ships, in 

 the water in harbours, which is often so extremely dirty, 

 &c., it is probable that the comma bacilli may retain 

 their vitality for a much longer time, and in the case of 

 a tank in India, where the small amount of stagnant 

 water was not only employed for bathing, drinking, and 

 cooking, but also for washing the linen and for the 

 reception of the contents of the water-closets, Koch was 

 able to demonstrate such a large number of comma 

 bacilli that it seemed likely that they had multiplied to a 

 great extent in the tank, and that their presence was in 

 all probability the source of infection of a number of 

 cases of cholera which occurred at a later period among 

 those persons who lived in the neighbourhood. 

 Influence of But ^ e factors which are concerned in infection by 



the individual cholera are not exhausted by the varying capabilities of 

 predisposition. , J J e . , 



the modes of transport. We are also compelled to 



assume that cholera does not by any means constantly 

 occur on every occasion when the comma bacilli have 

 passed the point of entrance and have reached the com- 

 mencement of the alimentary canal ; on the contrary, a 

 further condition comes into play, namely, the so-called 

 Protective individual predisposition. In a perfectly healthy person 

 * fc * s ev ^ en * from what we have learned from experi- 

 ments as to the destruction of the comma bacilli, and 

 from experiments on animals, that the comma bacilli 

 may be destroyed in the stomach, more especially by the 

 hydrochloric acid present in the gastric juice ; it is also 

 conceivable that the food may pass too rapidly through 

 the small intestine, and that also the digestive fluids or 

 the products of digestion may interfere with the growth 

 and development of the comma bacilli ; and finally the 

 energy of the cells and their resisting power towards the 

 toxic products of the bacilli come into play. According 



