DIPHTHERIA. 4°7 



Park ' found virulent diphtheria bacilli in about i per 

 cent, of the healthy throats examined in New York City. 

 Diphtheria was, however, prevalent in the city at the 

 time. Most of the persons in whose throats they existed 

 had been in direct contact with cases of diphtheria. Very 

 many of those whose throats contained the virulent bacilli 

 did not develop diphtheria. He concludes that the mem- 

 bers of a household in which a case of diphtheria exists 

 should be regarded as sources of danger, unless cultures 

 from their throats show the absence of diphtheria bacilli. 



In connection with the contagiousness of diphtheria 

 the recent experiments of Reyes are interesting. He 

 has demonstrated that in absolutely dried air distributed 

 diphtheria bacilli die in a few hours. Under ordinary 

 conditions their vitality, when dried on paper, silk, etc., 

 continues for a few days. In air that is moist the dura- 

 tion of vitality is prolonged to about a week. In sand 

 exposed to a dry atmosphere they die in five days in the 

 light; in sixteen to eighteen days in the dark. When 

 the sand is exposed to a moist atmosphere the duration 

 of vitality is doubled. In fine earth they remained alive 

 seventy-five to one hundred and five days in dry air, and 

 one hundred and twenty days in moist air. 



From time to time reference has been made to the 

 toxin elaborated by the diphtheria bacillus. Roux and 

 Yersin 2 first demonstrated the existence of this substance 

 in cultures passed through a Pasteur porcelain filter. 

 The toxin is intensely poisonous; it is not an albumin- 

 ous substance, and can be elaborated by the bacilli 

 when grown in non-albuminous urine, or, as suggested 

 by Uschinsky. in non-albuminous solutions whose prin- 

 cipal ingredient is asparagin. The toxic value of the 

 cultures is greatest in the second or third week. 



In addition to the toxin, a toxalbumin has been isolated 

 by Brieger and Frankel. 



1 Report on Bacteriological Investigations and Diagnosis of Diphtheria, from 

 May 4, 1893, to May 4, 1894, Scientific Bulletin No. 1, Health Department, 

 City of New York. 



2 Ann. de I'Inst. Pasteur, 1888, 1889, 1890, and 1894. 



