474 CHOLERA 



these methods, the appearance of the colonies in plates should 

 be specially noted, the test for the cholera-red reaction should 

 be applied, and in many cases it is advisable to test the effects 

 of intraperitoneal injection of a portion of a recent agar culture 

 in a guinea-pig, the amount sufficient to cause death being also 

 ascertained. The agglutinating or sedimenting properties of the 

 serum of the patient should be tested against a known cholera 

 organism, and against the spirillum cultivated from the case. 

 The action of an anti-cholera serum-, i.e., the serum of an animal 

 immunised against the cholera spirillum, should be tested in a 

 similar manner. 



Up till recent times there had been cultivated, from sources 

 other than cholera cases, no organism which gave all the cultural 

 and serum tests (agglutination and Pfeiffer's reaction) of the 

 cholera spirillum. In 1905, however, Gotschlich obtained six 

 different strains of a spirillum which conformed in all these 

 respects. The organisms were obtained at El Tor from the 

 intestines of pilgrims who had died with dysenteric symptoms, 

 and there were no cases of cholera in the vicinity. The organisms 

 in question, however, differ from the cholera organism in having 

 marked haemolytic action, and also in producing a rapidly acting 

 extracellular toxin. Kraus and others have found, on comparing 

 anti-sera to the cholera and El Tor spirilla, that while the anti- 

 bacterial properties are similar there is a difference in antitoxic 

 action. The El Tor antitoxin neutralises the cholera toxin, but 

 a cholera antitoxin has no effect on the El Tor toxin ; the El Tor 

 spirillum is thus peculiar as regards its toxic products. There 

 is accordingly difference of opinion as to whether these organisms 

 are to be regarded as a distinct species or as true cholera spirilla 

 which had been carried by the patients, though no symptoms 

 resulted from their presence. In view, however, of what we 

 know of variations in the type of the cholera organism, the latter 

 possibility is probably the case. This instance exemplifies well 

 the difficulties which may surround the identification of a 

 particular organism obtained from non-cholera cases ; but none 

 of the facts ascertained really affect the question as to the causal 

 relationship of Koch's spirillum to cholera. 



General Summary. We may briefly summarise as follows 

 the facts in favour of Koch's spirillum being the cause of cholera : 

 First, there is the constant presence of spirilla in true cases 

 of cholera, which on the whole conform closely with Koch's 

 description, though variations undoubtedly occur. Moreover, 

 the facts known with regard to their conditions of growth, etc., 

 are in conformity with the origin and spread of cholera epidemics. 



