SOFT SORE 



269 



aniline-oil method (vide p. 101) should be used for this purpose, 

 as alcohol decolorises the organism very readily. A little of the 

 methylene-blue or other stain may be added with advantage to 

 the aniline-oil used for dehydrating. 



Cultivation. Although for a long period of time attempts 

 to obtain cultures were unsuccessful, success has been attained 

 within recent years. Benzanon, Griffon, and Le Sourd obtained 

 pure cultures in four cases, the medium used being a mixture of 

 rabbit's blood and agar, 

 in the proportion of one 

 part of the former to 

 two of the latter. The 

 blood is added to the 

 agar in the melted con- 

 dition at 45 C., and 

 the tubes are then 

 sloped. Davis confirms 

 these results, and finds 

 that another good me- 

 dium is freshly -drawn 

 human blood distributed 

 in small tubes ; this 

 method is specially suit- 

 able, as the blood in- 

 hibits the growth of 

 various extraneous or- 

 ganisms. On the solid 



medium (blood-agar) the growth appears in the form of small 

 round globules, which attain their complete development in 

 forty-eight hours, having then a diameter of 1 to 2 mm. ; the 

 colonies do not become confluent. Microscopic examination of 

 these colonies, which are dissociated with some difficulty, shows 

 appearances similar to those observed when the organism is in 

 the tissues (Fig. 77), but occasionally long undivided filaments are 

 observed which Davis regards as degenerative forms. Within a 

 comparatively short period cultures undergo marked degenera- 

 tive changes, and great irregularities of form and shape are to be 

 found. It would appear that a comparatively large amount of 

 blood is necessary for the growth of this organism, and even 

 sub-cultures on the ordinary media, including blood-serum media, 

 give negative results. Inoculation of the ordinary laboratory 

 animals is not attended by any result, but it has been found 

 that some monkeys are susceptible, small ulcerations being 

 1 We are indebted to Dr. Davis for the use of Figs. 76 and 77. 



FIG. 77. Ducrey's bacillus from a 24-hour 

 culture in blood-bouillon, x 1500. l 



