660 CONDITIONS AFFECTING THE DEATH OF FUNGI. 



By cultivation 

 in an appa- 

 ratus kept 

 constantly in 

 motion. 



By long- 

 continued 

 cultivation. 



By light and 

 pressure. 



Attenuation 

 of the bacilli 

 of fowl 

 cholera. 



Of sympto- 

 matic anthrax. 



Of swine 

 erysipelas. 



Attenuation 

 of the virus 

 of rabies. 



Bucliner obtained loss of virulence in the anthrax 

 bacilli if he cultivated them outside the body for a 

 number of generations in certain nutrient substrata, 

 such as in extract of meat solution, with or without 

 peptone, to which a very plentiful supply of air was 

 added by the employment of an apparatus which kept 

 the solution in constant motion. There were many 

 objections to this method as first described by Buchner 

 (p. 240) ; but protective inoculations which have been 

 made by Frank with Buchner 's attenuated anthrax bacilli 

 show that, as a matter of fact, a gradual loss of virulence 

 can be obtained by this method. 



A diminution of virulence also appears to occur when 

 the anthrax bacilli are kept for a long time in the same 

 culture fluid (Koch). 



Lastly, according to Arloing,* exposure for three 

 hours to sunlight, and, according to Chauveau and 

 Wossnessenski,*!* increased atmospheric pressure, cause 

 an attenuation of the anthrax bacilli. 



Among other pathogenic bacteria the bacilli of fowl 

 cholera, of symptomatic anthrax, and of swine erysipelas 

 show a similar behaviour. In the case of the first- 

 mentioned bacillus the mode of the attenuation has not 

 as yet been accurately ascertained (p. 317) ; in the case of 

 symptomatic anthrax the attenuation is best obtained by 

 the employment of high temperatures (p. 301) . A special 

 and new principle has been followed by Pasteur in the 

 case of the bacilli of swine erysipelas ; he found that 

 their virulence was increased by repeated transmission 

 of the infective agents through pigeons, while, on the 

 other hand, it was diminished by their acclimatisation 

 in the bodies of rabbits (p. 307). 



Another plan, and one not as yet completely explained, 

 has been recently employed by Pasteur J for the attenua- 

 tion of the virulence of the poison of rabies. Pasteur's 

 method is shortly as follows : As the infective agents 

 of rabies are as yet completely unknown, and have not 

 been cultivated artificially, a pure rabic poison, and 



* Compt. rend., vol. 99. f ibid., vcl. 98. 



J Compt. rend., 1885, 26th October. 



