120 BACTERIOLOGY FOR NURSES 



Some of the very serious complications of diph- 

 theria, as the extensive swelhng and suppuration of 

 the glands of the neck, are due to pus infections; 

 apparently the diphtheritic lesion affords an avenue 

 for the entrance of pyogenic organisms. It is in these 

 compHcated cases of diphtheria that the antidiph- 

 theritic serum has little effect. 



Diphtheria Infection in the Lower Animals. — By 

 inoculation of the lower animals typical diphtheria 

 with all of the local and general symptoms can be 

 reproduced. Cats, dogs, pigeons, and guinea pigs 

 are the most susceptible, rabbits somewhat less so, 

 and rats and mice the most resistant. 



The Toxins of Diphtheria. — The fact that the 

 bacillus of diphtheria is found only at the point of 

 infection and not in the internal organs, although 

 profound changes are wrought in these organs, led 

 to the conclusion that these changes were due to sol- 

 uble poisons (toxins), produced by the bacilli at 

 the point of infection, which gain access to the 

 general circulation and are carried to the distant 

 organs affected. This poison is known as a toxal- 

 bumin, and in its chemical composition is analogous 

 to the venom of poisonous serpents. If kept in the 

 dark at a low temperature, the toxin of diphtheria 

 may retain its activity for months, but its toxicity 



