374 



MICRO-ORGANIS:MS and disease [chap. 



important experiments have been made by Behring and 

 Kitasato, Kitasato, Roux and Vaillard as to the nature and 

 action of the tetanus-toxin {see Immunisation and Antitoxin), 

 obtained in the filtrate of broth cultures. 



Different kinds of flasks and test tubes have been 

 designed which permit replacing tlic air above the broth 



Fig. 151. — Film Spf.cimen- of Suecut,\nf,ous CFdem.^ Fluid of \ Guixea-tig 

 DKAU OF ^Malignant CEdema ; Filamenlous For.ms of the Bacillus of 

 Malig.n'-\nt CFdema. 



X 1000. 



(after inoculation) by hydrogen gas — generally the flask or 

 test tube possesses a lateral tube so as to allow of this replace- 

 ment being easily effected. I find, however, that the 

 anaerobic microbes grow well in ordinary flasks and test 

 tubes, provided there is a large amount of the broth (three- 

 quarters or more of the volume) and the flask or test tubes 



