190 BACTERIA. 



disposing effect of autumnal gastric disturbances and slight 

 diarrhoea, which have, in many epidemics, been the in- 

 variable precursors of the true Asiatic or Indian cholera. 

 It is known that during an epidemic one attack of cholera, 

 especially a severe one, exerts a great protective influence 

 on those who survive, and as these consist almost ex- 

 clusively of the people who under ordinary circumstances 

 are again most exposed to infection, there may be natural 

 breaks in the line of extension of an advancing epidemic ; 

 breaks which have been used, by some authorities, as evi- 

 dence of the sporadic outbreak of the disease. 



So much has the study of Koch's comma bacillus tinged 

 and affected all our ways of looking at cholera epidemics 

 that we now consider the conditions under which the 

 bacillus can multiply and be carried from point to point, 

 and the conditions that favour its development and mul- 

 tiplication, instead of dealing with cholera itself as the 

 entity with which we have to contend. The epidemiologist 

 has now assumed the role of biologist in the widest sense 

 of the term. The bacteriological hygienist agrees with the 

 " localist " that it is necessary to get rid of all conditions 

 in which the cholera poison can be propagated and dis- 

 tributed, and that to this end the ground water should 

 be kept as free as possible from sewage, that all areas should 

 be properly drained, and that everything should be done 

 to render the l< drying zone ' as little congenial to the 

 bacillus as possible ; but he goes further, and insists that 

 the poison should not be allowed to be introduced into 

 localities in which it does not already exist, for he believes 

 that however favourable the conditions may be, there will 

 be no outbreak of cholera until the bacillus is introduced 

 and gains a foothold. He therefore insists on careful in- 

 spection of all ships coming from India or from other cholera- 

 stricken regions, though he is firmly convinced that it is 

 only in seaport towns that inspection or quarantine can 

 be of any value ; that if cholera makes its way beyond the 

 seaport no quarantine or sanitary cordon can stop its spread ; 

 that once beyond port the most careful isolation of all 

 patients and disinfection of every article of clothing, feeding 

 utensils, &c., should be rigidly carried out and insisted upon; 

 that the dejecta should be mixed with large quantities of 

 carbolic acid, concentrated hydrochloric acid, or strong cor- 



