444 A MANUAL OF BACTERIOLOGY 



nitrite poisoning, the nitrites being produced by the 

 reducing action of the vibrios on nitrates present. 



Anti-serum. By growing the cholera vibrio in a 

 shallow layer with free access of oxygen in a peptone 

 gelatin-salt medium, Metchnikoff and his co-workers 

 obtained a toxic fluid after three or four days growth. 

 During incubation the fluid becomes concentrated to about 

 one-eighth by evaporation. After filtration, 0-25 c.c. 

 killed a 300-grm. guinea-pig in eighteen hours. Goats, 

 inoculated with increasing doses of this toxin, com- 

 mencing with 10 c.c. and reaching 200 c.c. in six months, 

 become immunised and yield an antitoxic serum, 1 c.c. 

 of which will neutralise four times the lethal dose of toxin. 

 Metchnikoff had previously found that young suckling 

 rabbits suffer from an intestinal cholera when fed with 

 cultures, so that the effect of the cholera antitoxin in 

 preventing intestinal cholera could be tested on these 

 animals. Experiment showed that of the treated rabbits, 

 51 per cent, survived, of the untreated only 19 per cent. 

 Salimbeni employed a serum prepared in this manner in 

 the treatment of cases of cholera in the Russian epidemic, 

 1910. 



Animals may be inoculated with dead and living cultures 

 and an immune serum so prepared, but no practical value 

 has yet attended the use of anti-sera in the treatment of 

 cholera. Macfadyen immunised a goat with cholera- cell 

 juice, and obtained a serum of which 5 -J-^- c.c. protected a 

 guinea-pig against three lethal doses of cholera culture. 



The writer prepared an anti-endotoxic serum in this 

 manner, with which a few cases of cholera were treated 

 in Russia. 1 



Vaccine. Ferran in 1885 first prepared a vaccine by 

 making cultures (mixed) in broth from cholera stools and 

 injecting 0-3-0-5 c.c. subcutaneously, but the reports of 



1 Lancet, 1910, vol. ii, October 22. 



