424 INFECTION AND IMMUNITY. 



lytic agent (pyocyanolysin) of an alkaline nature, 



which resists boiling and is not a true toxin, since 



immunization with it does not yield an antitoxin 



Toxin and (Jordan). In addition to the products mentioned, 



Antitoxin. ^ or g an i sm secretes a true soluble toxin for 



which it is possible to obtain an antitoxin, and 



possesses, furthermore, an endotoxin for which 



an antitoxin can not be obtained. 



The soluble toxin of Bacillus pyocyaneus is not 

 produced in large amounts. It differs from the 

 other soluble toxins in its resistance to heat, with- 

 standing a temperature of 100 C. for five min- 

 utes. It produces the symptoms which are char- 

 acteristic of infection with the living organism, 

 the principal anatomic changes being parenchyma- 

 tous degenerations and ecchymoses, the latter sup- 

 posedly being due to degenerative changes in the 

 endothelium of the vessels. 



Antitoxic and By immunizing with young cultures grown on 

 Ct lerum f s! an agar surface, a serum which is bactericidal 

 and opsonic is obtained. On the other hand, 

 if an older toxin-containing bouillon culture be 

 used, the serum is opsonic, bactericidal and 

 antitoxic. The serum which is bactericidal and 

 opsonic has no power of neutralizing the toxin. 

 The toxin solution contains not only the true 

 toxin, but also quantities of endotoxin which 

 were liberated as the dead bacilli were dissolved. 

 Inasmuch as the antitoxin neutralizes only the 

 true toxin, leaving the endotoxin unbound, the 

 toxicity of the filtrate cannot be destroyed entirely 

 by antitoxin, a condition which is brought out 

 clearly when the attempt is made to neutral- 

 ize a multiple of the simple fatal dose by the 

 corresponding amount of antitoxin. In such mul- 



