406 PATHOGENIC BACTERIA. 



has so many points in common with the real diphtheria 

 bacillus that it is difficult to distinguish between them. 

 The chief points of difference between these bacilli are 

 that the pseudodiphtheria bacillus seems to be shorter 

 than the diphtheria bacillus when grown upon blood- 

 serum; that the cultures in bouillon seem to progress 

 much more rapidly at a temperature of from 20°-22° C. 

 than those of the true bacillus ; and that the pseudobacil- 

 lus is not pathogenic for animals. These slight distinc- 

 tions are, however, exactly what should be expected of 

 an organism whose virulence had been lost, and whose 

 vegetative powers had been altered, by persistent manip- 

 ulation or by unfavorable surroundings. 



The diphtheria bacilli are always present in the throats 

 of patients suffering from diphtheria, and constitute the 

 element of contagion by being accidentally discharged 

 by the nose or mouth by coughing, sneezing, vomiting, 

 etc. Whoever comes in contact with such materials is 

 in danger of infection. 



It is of great interest to notice the remarkable results 

 obtained by Biggs, Park, and Beebe in New York, where 

 the bacteriological examinations conducted in connection 

 with diphtheria show that the virulent bacilli may be 

 found in the throats of convalescents as long as five weeks 

 after the discharge of the membrane and the commence- 

 ment of recovery, and that they exist not only in the 

 throats of the patients themselves, but also in the throats 

 of their care-takers, who, while not themselves infected, 

 may be the means of conveying the disease from the 

 sick-room to the outer world. Even more extraordinary 

 are the observations of Hewlett and Nolen, 1 who found 

 the bacilli in the throats of patients seven, nine, and in 

 one case twenty-three weeks after convalescence. The 

 importance of this observation must be apparent to all 

 readers, and serves as further evidence why most thor- 

 ough isolation should be practised in connection with 

 this dreadful disease. 



1 Brit. Med. Jour., Feb. I, 1896. 



