MORPHOLOGY 491 



soft and flabby, the temperature fell to 30 C. or below and death took place, 

 occasionally after a very prolonged agony. Post mortem, there were no 

 lesions of the abdominal or thoracic viscera, the small intestine alone being 

 hypersemic, pink in colour and distended with a turbid fluid : the caecum 

 contained a large amount of thick alkaline serous fluid with mucous flakes 

 in suspension. The fluid in the small intestine contained an enormous 

 number of vibrios, most frequently in pure culture. The micro-organisms 

 ingested at the same time as the vibrios disappeared after performing their 

 ancillary role. In one-fourth of the cases the vibrio passed into the blood 

 stream. 



When young rabbits cease to feed entirely on milk their susceptibility to 

 infection with cholera vanishes, and an immunity is established which cannot 

 be overcome even with the assistance of other micro-organisms. The 

 intestinal cholera of young rabbits is contagious and may be transmitted 

 by the mammse of the mother during suckling of the infected animals. 



Young guinea-pigs a few days old are much less susceptible to infection 

 than rabbits when fed with a mixture of the Massaouah vibrio and ancillary 

 organisms. The disease from which they suffer is less characteristic of cholera 

 than the disease in rabbits, and the vibrio exhibits a greater tendency to 

 become generalized in the tissues of guinea-pigs. 



Man. 



It is many years since experiments were first conducted with a view to 

 infecting the human subject with cholera by the alimentary canal (Boche- 

 fontaine, Klein). In 1892, Pettenkofer and Emmerich swallowed pure cul- 

 tures of Koch's vibrio, but though they had previously taken carbonate of 

 soda and strictly regulated their diet, they merely suffered from an attack 

 of choleraic diarrhoea unaccompanied by any general symptoms. 



Hasterlik and Strieker, and Ferran also suffered from diarrhoea and vomiting 

 after taking pure cultures of the vibrio. 



On several occasions Metchnikoff and his pupils drank pure cultures of 

 vibrios from different sources (from Hamburg, Courbevoie, Saint-Cloud, 

 Paris, Versailles, etc.). The observer first took a gram of bi-carbonate of 

 soda dissolved in a little water and immediately afterwards a varying amount 

 of an agar culture rubbed up in a little sterile broth. Metchnikoff was able 

 in this way to produce " a true asiatic cholera which although slight had 

 all the classical symptoms " of the disease : 

 '" rice water " stools, sub-normal temperature, jr 



vomiting, cramps, suppression of urine, and ^ - ^ 



vibrios in almost pure culture in the stools. ^ ^ 



_ - 



SECTION H. MORPHOLOGY. . x o> 



f - ^ f* 



Cholera vibrios are essentially pleomorphic ; x f 



their shape, the number of their flagella and f * 



their cultural characteristics being all very vari- \ I * 



able. This pleomorphism renders their identifi- 

 cation singularly difficult. ^t 



FIG. 237. Vibrio ckolerce (Indian 



1. Microscopical appearance. strain). Film from an agar culture. 



Dilute carbol-fuchsin. (Reich ; oc. 



The typical cholera vibrio (of Koch) occurs as n. : obj. T uh.) 

 a stumpy rod 1'5-3/x, long and 0'5-0'6/j broad 



slightly curved like a comma ; the degree of curvature is very variable. In 

 the field of the microscope some of the vibrios appear to be straight, but 



