X. 



CHOLERA, PLAGUE, TYPHOID FEVER 



CHOLERA 



KOCH, in 1883, observed and described the germs 

 of this disease : but it was not until 1892, the year 

 of the Hamburg epidemic, that men of science, in 

 all countries, were practically unanimous in their 

 acceptance of his discovery. 



Nothing, in all bacteriology, was more complex 

 and laborious than the international work over 

 Asiatic cholera. For there are many sub-species 

 of these germs ; and their variations, wide range 

 of virulence, instability, and diversity of behaviour, 

 are bewildering even to read of: 



"Variability of some degree is proper to all 

 germs, as it is to higher animals and plants ; but 

 the cholera microbe is one of those in which, owing 

 to their organisation and mode of life, that variability 

 is particularly marked ; so much so that not unfre- 

 quently, after an examination with all available tests, 

 it is impossible to say whether the germ dealt with 

 is, or is not, a representative of the cholera species." 



110 



