vin] THE INFECTIVENESS OF CHOLERA. 151 



rule, the very months when epidemics of cholera are rare ; 

 when they do occur, they occur as a rule between the end 

 of April and October. The epidemic in Egypt in 1883, the 

 very epidemic that preceded those of Toulon and Marseilles 

 in 1884, approached its end by the end of October. 



If the comma-bacilli were possessed of the power of 

 forming spores, and if only in this state they were capable of 

 producing infection, one could understand that this forma- 

 tion of spores, as is the case with some other bacilli, might 

 be dependent on certain definite conditions, amongst which 

 might be a certain locality and a certain season. But such 

 is not the case ; Koch is very definite about it, and others 

 who have devoted special attention to this point are equally 

 definite ; I have in a previous chapter discussed this point 

 in detail, and have explained certain appearances which 

 Hueppe thought sufficient for assuming the existence of 

 spore-formation in comma-bacilli. When spore-formation 

 does occur there is no difficulty in demonstrating it ; 

 but in the case of the comma-bacilli such a phase is not 

 demonstrated. 



Again, if the comma-bacilli were dependent on some 

 special nutriment obtainable only during certain parts of the 

 year and not in others, or if the habits of the people differed 

 as regards cleanliness, water-supply, &c. in certain parts of 

 the year, a difference in the spread of the disease might be 

 then accounted for : but the comma-bacilli live and thrive 

 wherever and whenever there is nitrogenous material in 

 fact, they are in this respect conspicuous by their small 

 selective power, they grow in all localities, in all climates, 

 and in all seasons. 



Then there is the question of the infective power of the 

 cholera-dejecta. If, as many believe, the fresh cholera- 

 dejecta were possessed of infective power, then it would 



