BACTERIA IN DIPHTHERIA. 461 



Park and Beebe (1894), in an extended research made for the pur- 

 pose of determining the persistence of the diphtheria bacillus in the 

 throats of convalescents ('2,500 cultures made), found that in 304 out 

 of 005 consecutive cases the bacillus disappeared within 3 days after 

 the disappearance of the exudate; in 170 cases it persisted for 7 days; 

 in 64 cases for 12 days; in 36 cases for 15 days; in 13 cases for 3 

 weeks; in 4 cases for 4 weeks; in 2 cases for 9 weeks. Park and 

 Beebe arrive at the following conclusion with reference to pseudo- 

 diphtheria bacilli : 



u The name pseudo-diphtheria bacillus should be regarded as ap- 

 plying to those bacilli found in the throat which, though resembling 

 the diphtheria bacilli in many respects, yet differ in others equally im- 

 portant. These bacilli are rather short, and more uniform in size 

 and shape than the typical Loffler bacillus. They stain equally 

 throughout with the alkaline methyl-blue solution, and produce 

 alkali in their growths in bouillon. They are found in about one 

 per cent of the healthy throats in New York City, and seem to have 

 no connection with diphtheria. They are never virulent." 



Park (1894) has shown that virulent diphtheria bacilli are fre- 

 quently found in the throats of persons who have been associated 

 with diphtheria patients, although no manifestations of the disease 

 were visible. It is therefore apparent that infection requires not 

 only the presence of virulent bacilli, but also of a predisposition to 

 the disease. This corresponds with the facts relating to other in- 

 fectious diseases e.g., tuberculosis, typhoid fever and among the 

 probable predisposing causes we may mention " sewer-gas poisoning," 

 catarrhal inflammations of the mucous membranes most commonly 

 involved, inanition, "crowd poisoning," and depressing agencies 

 generally. 



Bacteriologists have given much attention to the question of mixed 

 infection in diphtheria. Funck (1894) accepts the generally received 

 view that mixed infections with the diphtheria bacillus and Strepto- 

 coccus pyogenes are more serious than an uncomplicated diphtheria, 

 and in an experimental research has attempted to determine whether 

 this is due to an increased production of the diphtheria bacillus or to 

 the presence of the streptococcus. His experiments on guinea-pigs 

 showed that when infected with streptococci these animals did not 

 prove to be more sensitive to the action of the diphtheria poison 

 (without living bacilli), and he concludes that the unfavorable influ- 

 ence of the streptococcus in mixed infections is due to increased patho- 

 genic activity on the part of the diphtheria bacillus. Bernheim 

 (1894) found, in his experiments on guinea-pigs, that they suc- 

 cumbed more rapidly to diphtheria infection when they previously 



