72 TOXINS AND ANTITOXINS. 



toxin * a culture of the bacillus is first made in a 

 mutton bouillon made strongly alkaline with so- 

 dium carbonate (10 grams per liter), and with the 

 addition of 2 per cent, of peptone. At the end 

 of about one month, the culture being kept at 

 about 37 C., the liquid is filtered through porce- 

 lain. It is indispensable to employ a very viru- 

 lent bacillus; it is hence frequently advantageous 

 to increase the virulence and toxigenic power of 

 the bacilli it is desired to use. 



The toxic liquid obtained is exceedingly power- 

 ful: o.i Cc. kills a rabbit in forty-eight hours. 

 This toxin is very sensitive to the effects of heat. 

 When heated to 65 C. it loses almost all its toxicity ; 

 at 70 C. it becomes innocuous ; and it only re- 

 quires to be heated to 100 C. for fifteen minutes 

 in order to lose all immediate activity even in large 

 doses. Nevertheless toxins thus weakened are 

 capable of proving fatal to an animal even after 

 five or six months. 



Light, oxygen, ozone and all oxidizers destroy the 

 active principle of the diphtheria toxin, which is, 

 moreover, rendered almost inactive by organic acids. 



This toxin is capable of diffusing through animal 

 membranes, a fact that is in agreement with the 

 toxic effect seen in a subject attacked with diph- 



* See SPRONK: Annal. de I'Instit. Pasteur, ix, p. 785; Ibid., 

 x, p. 333; MARTIN, Ibid., xn, p. 26; SPRONK, Ibid., xii, p. 711. 



