SPIRILLUM CHOLERA ASIATICS. 447 



to the greater or less perfection of the protecting and 

 regulating arrangements of the body the same infective 

 material will in one case cause no disturbance, in 

 another only slight diarrhoea, which leads to rapid 

 removal of the multiplying bacilli, and the rapid victory 

 of the body, and in a third to serious illness. We Acquired 

 have also the experience that one attack of cholera pro- 

 duces immunity for a considerable period of time. The 

 milder or severer course of the disease does not in this 

 instance appear to make any difference ; the cases also 

 where the regulating arrangements of the body are in 

 such good condition that the reaction to the infection is 

 so slight as scarcely to be designated as disease, ap- 

 parently acquire this immunity. It has not as yet 

 been definitely ascertained how long this immunity 

 lasts ; it is probable that it may last on an average for 

 3 or 4 years, at any rate it usually lasts for several 

 months, so that an individual is seldom attacked twice 

 during the same epidemic. 



On the other hand we must assume that the bodv is Predisposing- 



factors 



more susceptible to infection when dyspeptic conditions 

 and slight gastric disturbances or overloading of the 

 stomach are present, also when the digestive process 

 has arrived at the stage where the acid reaction of the 

 intestinal contents is slight : and likewise when large 

 quantities of food can pass into the small intestine after 

 a relatively short delay in the stomach, and when, on 

 the other hand, the onward progress of the food in the 

 small intestine is abnormally slow. The exact value of 

 these and other assisting factors cannot as yet be 

 accurately determined, but that as a rule factors of this 

 kind come into play is clear from the fact that most 

 cases of cholera occur on Mondays and Tuesdays, after 

 there have been excesses in eating and drinking on the 

 Sunday ; and also from the observation made by 

 Virchow that on post-mortem examination of verv acute 

 cases of cholera there are always signs that digestion 

 has been going on actively. Another predisposing 

 factor seems to consist in the general weakening of the 

 body, such as is occasioned by poverty, hunger, and 



