410 CHOLERA 



Attempts to investigate the chemical nature of the toxic bodies 

 have not led to definite results. 



Experiments on the Human Subject. Experiments have also 

 been performed in the case of the human subject, both intention- 

 ally and accidentally. In the course of Koch's earlier work, one 

 of the workers in his laboratory shortly after leaving was seized 

 with severe choleraic symptoms. The stools were found to 

 contain cholera spirilla in enormous numbers. Recovery, how- 

 ever, took place. In this case there was no other possible 

 source of infection than the cultures with which the man had 

 been working, as no cholera was present in Germany at the time. 

 Within recent years a considerable number of experiments have 

 been performed on the human subject, which certainly show that 

 in some cases more or less severe choleraic symptoms may follow 

 ingestion of pure cultures, whilst in others no effects may result. 

 The former was the case, for example, with Emmerich and 

 Pettenkofer, who made experiments on themselves, the former 

 especially becoming seriously ill. In the case of both, diarrhoea 

 was well marked, and numerous cholera spirilla were present in 

 the stools, though toxic symptoms were proportionately little 

 pronounced. Metchnikoff also, by experiments on himself and 

 others, obtained results which convinced him of the specific 

 relation of the cholera spirillum to the disease. Lastly, we may 

 mention the case of Dr. Orgel in Hamburg, who contracted the 

 disease in the course of experiments with the cholera and other 

 spirilla, and died in spite of treatment. It is believed that in 

 sucking up some peritoneal fluid containing cholera spirilla, a 

 little entered his mouth and thus infection was produced. This 

 took place in September 1894 at a time when there was no 

 cholera in Germany. On the other hand, in many cases the 

 experimental ingestion of cholera spirilla by the human subject 

 has given negative results. Still, as the result of observation of 

 what takes place in a cholera epidemic, it is the general opinion 

 of authorities that only a certain proportion of people are 

 susceptible to cholera, and the facts mentioned above are, in our 

 opinion, of the greatest importance in establishing the relation 

 of the organism to the disease. 



Immunity. As this subject is discussed later, only a few 

 facts will be here stated, chiefly for the purpose of making clear 

 what follows with regard to the means of distinguishing the 

 cholera spirillum from other organisms. The guinea-pig or any 

 other animal may be .easily immunised against the cholera 

 organism by repeated injections (conveniently made into the 

 peritoneum) of non-fatal doses of the spirilla. It is better to 



