462 CHOLERA 



Koch's spirillum is the cause of the disease, have been of the 

 greatest value in the diagnosis of the disease. And lastly, the 

 results of Haffkine's method of preventive inoculation in the 

 human subject, which are on the whole favourable, also supply 

 additional evidence. If all these facts are taken together, we 

 consider the conclusion must be arrived at that the growth of 

 Koch's spirillum in the intestine is the immediate cause of the 

 disease. This does not exclude the probability of an important 

 part being played by conditions of weather and locality, though 

 such are very imperfectly understood. Pettenkofer, for example, 

 recognised two main factors in the causation of epidemics, w r hich 

 he designated x and y, and considered that these tw r o must be 

 present together in order that cholera may spread. The or is the 

 direct cause of the disease an organism which he admitted 

 to be Koch's spirillum ; the y includes climatic and local con- 

 ditions, e.g. state of ground-water, etc. 



Other Spirilla resembling the Cholera Organism. These 

 have been chiefly obtained either from water contaminated by 

 sewage or from the intestinal discharge in cases with choleraic 

 symptoms. Some of them differ so widely in their cultural and 

 other characters (some, for example, are phosphorescent) that no 

 one would hesitate to classify them as distinct species. Others, 

 however, closely resemble the cholera organism. 



The vibrio berolinensis, cultivated by Neisser from Berlin sewage 

 water, differs from the cholera organism only in the appearance of its 

 colonies in gelatin plates, its weak pathogenic action, and its giving a 

 negative result with Pfeiffer's test. It, however, gives the cholera-red 

 reaction. The vibrio Danubicus, cultivated by Heider from canal water, 

 also differs in the appearance of its colonies in plates, and also reacts 

 negatively to Pfeiffer's test ; in most respects it closely resembles the 

 cholera organism. Another spirillum (v. Ivanoff) was cultivated by 

 IvanofFfrom the stools of a typhoid patient after these had been diluted 

 with water. The organism differed somewhat in the appearance of its 

 colonies and in its great tendency to grow out in the form of long 

 threads, but Pfeiffer found that it reacted to his test in the same way as 

 the cholera organism, and he considered that it was really a variety of 

 the cholera organism. No spirilla could be found microscopically in the 

 stools in this case, and Pfeiffer is of the opinion that the organism 

 gained entrance accidentally. These examples will show how differences 

 of opinion, even amongst experts, might arise as to whether a certain 

 spirillum were really the cholera organism or a distinct species resem- 

 bling it. 



A few examples may also be given of organisms cultivated 

 from cases in which cholera- like symptoms were present. 



The vibrio of Massowah was cultivated by Pasquale from a case during 



