Specificity 435 



characteristic of the true diphtheria organism. The chief 

 points of difference between the bacilli are that the pseudo- 

 diphtheria bacillus, when grown upon blood-serum, is short 

 and stains uniformly; that cultures grown in bouillon 

 develop more rapidly at a temperature of from 2o-22 C. 

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

 is not pathogenic for animals. These distinctions are, 

 however, exactly what would be expected of an organism 

 whose virulence and vegetative powers had been altered, 

 by persistent manipulation or by unfavorable environment. 



Contagion. The diphtheria bacilli, being always present 

 in the throats of patients suffering from diphtheria, con- 

 stitute the element of contagion, and by being accidentally 

 discharged from the nose and mouth during coughing, 

 sneezing, vomiting, etc., endanger whoever comes in contact 

 with the patient. 



The results obtained by Biggs, Park, and Beebe in New 

 York are of great interest. Bacteriologic examinations 

 conducted in connection with the Health Department of 

 New York city show that virulent diphtheria bacilli may 

 be found in the throats of convalescents from diphtheria, 

 as long as five weeks after the discharge of the membrane 

 and the commencement of recovery, and that they exist 

 not only in the throats of the patients themselves, but also 

 in those of their caretakers, who, while not themselves 

 infected, may be the means of conveying the disease germs 

 from the sick-room to the outer world. Still more extra- 

 ordinary are the observations of Hewlett and Nolen,* that 

 the bacilli remained in the throats of patients seven, 

 nine, and in one case twenty-three weeks after convalescence. 

 The hygienic importance of this observation must be ap- 

 parent to all readers, and serves as further evidence why 

 thorough isolation should be practised in connection with the 

 disease. 



Neumann f found that virulent diphtheria bacilli may 

 occur in the nose with the production of what seems to be 

 a simple rhinitis as well as a pseudo-membranous rhinitis. 

 Such cases, not being segregated, may easily serve to spread 

 the contagion of the disease. 



Wesbrook, and Wilson and McDaniel % have found it con- 



* "Brit. Med. Jour.," Feb. 1, 1896. 



f " Centralbl. f. Bakt. u. Parasitenk.," Jan. 24, 1902, Bd. xxxi, 

 No. 2, p. 41. 



| "Trans. Assoc. Amer. Phys.," 1900. 



