228 GONORRHOEA, SOFT SORE, SYPHILIS 



but loses the colour very rapidly when a decolorising agent is 

 applied. Accordingly, in film preparations when dehydration 

 is not required, it can be readily stained by most of the 

 ordinary combinations, though Loffler's or Kiihne's methylene- 

 blue solutions are preferable, as they do not overstain. In 

 sections, however, great care must be taken in the process of 

 dehydration, and the aniline-oil method (vide p. 93) should be 

 used for this purpose, as alcohol decolorises the organism very 

 readily. A little of the methylene-blue or other stain may be 

 with advantage added 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. 



^ + ^ Benzangon, 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 condition at 

 45 C., and the tubes are 

 then sloped. Davis con- 

 firms these results, and 

 finds that another good 

 medium is freshly-drawn 

 human blood distributed 

 in small tubes ; this 



method is specially suitable, as the blood inhibits the growth 

 of various extraneous organisms. 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 similar appear- 

 ances 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 degenerative changes, and 

 great irregularities of form and shape are to be found. It 



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. 1 



