362 Chancroid 



Davis* have abundantly confirmed the observations of 

 Ducrey and Unna, and proved the identity of the two 

 micro-organisms and their specificity for the disease. 



Morphology. The organism is commonly described as 

 a 'strepto-bacillus." It is short and ovoid in shape, and 

 occurs habitually in longer or shorter chains. Each organ- 

 ism measures about 1.5 X 0.5 p.. The ends are rounded and 

 stain deeply. In pure cultures long undivided filaments, 

 at least twenty times as long as the individual bacilli, are 

 not uncommon. There seems to be no relation between 

 the cells and the bacilli. As a rule, they are free, sometimes 

 they are inclosed in leukocytes. 



Staining. The organisms are somewhat difficult to stain, 

 as they do not retain the color well, giving it up quickly 

 when washed. They do not stain by Gram's method. 



Cultivation. The first successful isolation and cultivation 

 of the organism seems to have been by Bezancon, Griffon 

 and Le Sourdf upon a culture medium consisting of rabbits' 

 blood i part, and agar-agar 2 parts. DavisJ has been 

 equally successful in cultivating the organism upon this 

 medium. His method was as follows : 



"Tubes of two per cent, agar, reaction + 1.5, were melted 

 and mixed with fresh rabbits' blood drawn under aseptic 

 precautions, in the proportion of two-thirds agar to one- 

 third blood, and slanted while in a fluid state. At a later 

 period tubes of rabbits' blood-serum uncoagulated, also 

 rabbits' blood bouillon, one-third blood to two- thirds bouil- 

 lon, were used, and gave equally satisfactory results. By 

 employing small tubes of freshly-drawn human blood, pure 

 cultures were obtained in several instances from genital 

 lesions direct without any special cleansing of the ulcerated 

 surface. This, I believe, is the best medium for obtaining 

 cultures from a source open to contamination, the fresh 

 blood apparently inhibiting to a certain extent the growth 

 of extraneous organisms." 



No growth takes place upon ordinary culture media under 

 either aerobic or anaerobic conditions. 



Colonies. The colonies appear upon the appropriate 

 media in about twenty-four hours and attain their complete 

 development in about forty-eight hours. They are at" first 

 round bright globules, and later become grayish and opaque. 



*Jour. Med. Research," 1893, ix, p. 401. 



f'Ann. de Dermat. et de Syphiligr., 1901, n, p. 1. %Loc. tit. 



