APPENDIX 285 



other slight general symptoms, which soon pass off ; locally, 

 however, severe inflammation and necrosis follow, unless 

 a preliminary injection has been made 3 to 5 days previously 

 with a weak vaccine prepared from cultures attenuated by 

 being grown in media kept continually aerated, and at 35° C. 

 The only local symptoms are then slight pain and oedema. 

 After the symptoms have passed off the animal is found to 

 be scarcely affected by many times larger intraperitoneal 

 injections than suffice to kill control animals not so pro- 

 tected. 



These results have also been obtained with rabbits and 

 pigeons, and the symptoms following injection into human 

 beings, of whom about a hundred had been vaccinated up 

 to March last,' are identical with those exhibited by all the 

 animals, subsequent hypodermic injections with the ex- 

 alted virus also producing the same results in both, so that 

 although, of course, human beings could not be directly 

 tested like the animals, there seems little room for doubt 

 that they are similarly protected. It may be added that 

 swallowing a draught of cholera bacilli in one case, and free 

 intentional exposure to contagion at Hamburgin another, pro- 

 duced no results in two observers who had been vaccinated. 



More recently, however, some doubt has been cast on 

 the efficacy of the process to protect against the ordinary 

 infection of cholera by Klein, ^ who found that precisely 

 similar results could be obtained with Vib7-io proteus, the 

 typhoid bacillus, Bacillus coli, Bacillus ■prodigiosiis, &c. Vac- 

 cination with an exalted virus prepared from any of these 

 conferred immunity against the cholera bacillus (even the 

 exalted virus) or any of the others, when injected intraperi- 

 toneally. He also found that guinea-pigs protected by Haff- 

 kine's method were killed by intraperitoneal injection of a 



' Haffkine, Fortnightly Review, March 1893. 

 2 Brit. Med. Journ., March 25, 18',)a, p. G32. 



