BACILLUS OF DUCREY 511 



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, 

 Besanc,on, Griffon, and Le Sourd 10 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 substituted for that of man. Since the work by these 

 authors, the cultivation by similar methods has been carried out by 

 a number of investigators. Coagulated blood, which has been kept 

 for several days in sterile tubes, has been found to constitute a favor- 

 able medium. Freshly clotted blood cannot be employed, probably 

 because of the bactericidal 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 

 consists 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 before the pus has had a chance to cool off or to be 

 exposed to light. When buboes are not available, the primary lesion 

 may be thoroughly cleansed with sterile water or salt solution, and 

 material scraped from the bottom of the ulcer or from beneath its 

 overhanging edges with a stiff platinum loop. This material is then 

 smeared over the surface of a number of blood-agar plates. 



Upon such plates, isolated colonies appear, usually after forty- 

 eight hours. They are small, transparent, and gray, and have a 

 rather firm, finely granular consistency. The colonies rarely grow 

 larger than pinhead size, and have no tendency to coalesce. At room 

 temperature, the cultures die out rapidly. Kept in the incubator, 

 however, they may remain alive and virulent for a week or more. 



On the simpler media, glucose-agar, broth, or gelatin, cultivation 

 is never successful. On moist blood-agar and in the condensation 

 water of such tubes, the bacilli have a tendency to grow out in long 

 chains. Upon media which are very dry, they appear singly or in 

 short chains. 



During recent years interest has again been aroused in the 



10 Besangon, Griffon, et Le Sourd, Presse med., 1900. 



