522 PATHOGENIC MICROORGANISMS 



ceeded in extracting from toxic bouillon a white, water-soluble powder 

 which possessed most of the poisonous properties of the broth itself. 

 This, in solution, gave many of the useful proteid reactions, but dif- 

 fered from proteids in failing to coagulate when boiled and in not 

 giving precipitates when treated with magnesium sulphate, sodium 

 sulphate, or nitric acid. It was believed by them to be closely related 

 to the albumoses, bodies representing intermediate phases in the pep- 

 tonization of albumins. Similar results have been obtained by Was- 

 sermann and Proskauer, 1 Brieger and Boer, 2 and others. Uschinsky, 3 

 on the other hand, has disputed the proteid nature of toxins in gen- 

 eral, having produced diphtheria toxin by growing the organism upon 

 a medium entirely free from albuminous bodies. Uschinsky believes 

 that the protein reactions observed by others may be due to ingredi- 

 ents of the precipitates other than the toxin. It is not impossible, 

 however, that the organisms may have produced proteid substances 

 by synthesis from the simpler substances in Uschinsky 's medium. The 

 production of toxin from such a medium, therefore, is not a conclusive 

 argument against the proteid nature of toxins. Accurate chemical iso- 

 lation and analysis of diphtheria toxin have not yet been accomplished. 



Diphtheria toxin is destroyed, 4 when in the fluid form, by tempera- 

 tures of 58 to 60 C. In the dry state, it resists a temperature of 

 70 C. and over, without change. Light and free access of air produce 

 rapid deterioration. Sealed, protected from light, and kept at almost 

 freezing point, the toxin remains stable for long periods. Electrical 

 currents passed through toxic broth have little or no effect upon it. 



Transmission. Diphtheria is transmitted from one individual to 

 another directly or indirectly by contact or droplet infection as in 

 coughing, etc. It has been found that individuals may retain virulent 

 diphtheria bacilli in nose and throat for long periods after recovery 

 from the disease. These are the so-called ''diphtheria carriers." 



The problem of diphtheria carriers has become one of considerable 

 importance and has been given special prominence of recent years by 

 the studies of Yon Scholly, Moss, and Nuttall and Graham Smith. 

 Anderson, Goldberger and Hachtel 5 studied 4,039 healthy people in 



1 Wassermann und Proskauer, Deut. med. Woch., 1891, p. 585. 



2 Brieger und Boer, Deut. med. Woch., 1896, p. 783. 



3 Uschinsky, Cent. f. Bakt., xxi, 1897. 



4 Roux et Yersin, loo. cit. 



* Goldberger, Williams and Hachtel, Bull. No. 101, of the Hygienic Laboratories, 

 of the U. S. Public Health Service. 



