Cultivation 443 



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 " strep tobacillus." It is very small, short, and ovoid in 

 shape, and occurs habitually in longer or shorter chains. 

 Each organism measures about 1.5 + 0.5 fi. 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. 



7 -*--< 



^r;* 



Fig. 138. Smear of pus of chancroid of penis stained with carbol- 

 fuchsin and briefly decolorized by alcohol. X 1500 (Davis). (Photo- 

 micrograph by Mr. L. S. Brown.) 



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 cultiva- 

 tion of the organism seems to have been by Benzancon, 

 Griffon and Le Sours f upon a culture-medium consisting of 

 rabbits' blood i part, and agar-agar 2 parts. Davis J has 

 been equally successful in cultivating the organism upon this 

 medium. His method was as follows: 



"Tubes of 2 per cent, agar, reaction + 1.5, were melted 



* " Jour. Med. Research," 1893, IX P- 4 QI - 



t ''Ann. de Dermat. et de Syphiligr.," 1901, n, p. i. 



J Loc. cit. 



