i6o Lectures on Bacteria. [^ xiit. 



Our knowledge of the Bacteria and of the real existence of 

 contagia viva was in a much more advanced state, when the 

 outbreak of the epidemic in Egypt in 1883 led to a fresh re- 

 sumption of the question. R. Koch, the most experienced 

 investigator of the subject, pursued his enquiries in Egypt and 

 in India, and there became acquainted with a distinctly marked 

 Bacterium-form which is found in the intestinal canal in fresh 

 cholera-cases, and was once observed also in a water-tank in a 

 cholera-district. This Bacterium he suspected to be the specific 

 contagium or miasma of the Indian pestilence ; we will for the 

 present call it a Spirillum. 



According to the facts as at present known, there can scarcely 

 be a doubt that Koch's Spirillum is really the contagium vivum 

 of Asiatic cholera. First of all, its constant presence — for we 

 may call it constant — in the small intestine or in the evacuations 

 of cholera-patients is acknowledged by all observers, even by 

 those -who do not accept Koch's views. It is sometimes found 

 almost as in the state of a pure culture in the mucus of the in- 

 testine in bodies examined immediately after death ; under other 

 circumstances certainly it is less pure and abundant. In the 

 exceptional cases in which it was not found, either strict search 

 was confessedly not made, or it may have been overlooked or 

 have actually disappeared, especially at an advanced stage of the 

 disease, and therefore have once been present. Koch's Spirillum 

 has never been found either in the intestinal canal or in any 

 other part of the body in any disease except Asiatic cholera. 



The Spirillum of cholera can readily be cultivated pure as a 

 saprophyte, as will be noticed again further on. Attempts to 

 inoculate animals with pure living material of this kind gave at 

 first only negative or in the most favourable case uncertain 

 results, and this is especially true with regard to the experiments 

 in which it was sought to convey infection with the food. It was 

 found that the Spirilla were killed by the acid gastric juice, or 

 were rendered inoperative by some other causes. But a change 

 in the mode of conducting the experiment led to a positive result. 



