548 PATHOGENIC MICROORGANISMS 



nature. Usually it leads to lymphatic swellings in the groin which, 

 later, give rise to abscesses, commonly spoken of as "buboes." 



In the discharges from such lesions, Ducrey, 1 in 1889, was able to 

 demonstrate minute bacilli to which he attributed an etiological rela- 

 tionship to the disease, both because of the regularity of their presence 

 in the lesions and the successful transference of the disease by means 

 of pus containing the microorganisms. 



Morphology and Staining. The Ducrey bacillus is an extremely 

 small bacillus, measuring from one to two micra in length and about 

 half a micron in thickness. It has a tendency to appear in short 

 chains and in parallel rows, but many of the microorganisms may be 

 seen irregularly grouped. It is not motile, possesses no flagella, and 

 does not form spores. 



Stained by the ordinary anilin dyes, it has a tendency to take the 

 color irregularly and to appear more deeply stained at the poles. By the 

 Gram method, it is decolorized. In tissue sections, it may be demon- 

 strated by Loeffler's methylene-blue method, and in such preparations 

 has been found within the granulation tissues forming the floor of the 

 ulcers. In pus, the bacilli are often found within leucocytes. 



Cultivation and Isolation. Early attempts at cultivation of this 

 bacillus were universally unsuccessful in spite of painstaking experi- 

 ments with media prepared of human skin and blood serum. In 1900, 

 Besanyon, Griffon, and Le Sourd 2 finally succeeded in obtaining growths 

 upon a medium containing agar to which human blood had been added. 

 They were equally successful when dog's or rabbit's blood was substi- 

 tuted for that of man. Since the work by these authors, the cultiva- 

 tion by similar methods has been carried out by a number of investiga- 

 tors. Coagulated blood, which has been kept for several days in sterile 

 tubes, has been found to constitute a favorable medium. Freshly 

 clotted blood can not be employed, probably because of the bacteri- 

 cidal action of the serum. Serum-agar has occasionally been used 

 with success, but does not give results as satisfactory as those obtained 

 by the use of the whole blood. 



The best method of obtaining pure cultures upon such media con- 

 sists in puncturing an unruptured bubo with a sterile hypodermic needle 

 and transferring the pus in considerable quantity directly to the agar. 

 If possible, the inoculation of the media should be made immediately 



1 Ducrey, Monatschr. f. prakt. Dermat., 9, 1889. 



2 Besanfon, Griffon, et Le Sourd, Presse m6d., 1900? 



