138 CLINICAL BACTERIOLOGY AND H^EMATOLOGY 



carbol fuchsin or Loffler's blue, and the other by Gram's 

 method. If the bacilli are present, they will appear as short 

 oval rods which may or may not exhibit the polar staining; 

 if the specimen has been stained for the proper length of 

 time (about two minutes), most of them will do so, but in any 

 case it will most likely be present in a few. The Gram speci- 

 men will not show these rods; there may be a few pus cocci 

 present as a secondary infection. 



The blood is examined by any of the methods to be 

 described subsequently, and a very careful search made, as 

 the numbers of the bacilli may be comparatively scanty. 



If a careful examination of stained films made from a bubo 

 does not show the organisms having the above characters, it 

 19 probably safe to say that the case is not one of plague. 



The certain recognition of the B. pestis is not easy, as other 

 organisms resemble it closely. The growth on agar is not charac- 

 teristic : it is whitish and abundant. Gelatin is not liquefied. Many 

 strains, but not all, give the appearance of stalactites hanging down 

 from the surface of the fluid when cultivated in broth kept absolutely 

 at rest. Rats, including white rats, are susceptible and die in two or 

 three days after subcutaneous injection, and bacilli are found in enor- 

 mous numbers in the blood. (Some allied organisms do not infect 

 white rats.) The organism is also said to grow on media containing 

 taurocholate of soda, whereas its allies will not. 



SOFT SORE 



Soft sore is now known to be due to the bacillus described 

 by Unna and by Ducrey.* It is apparently invariably present 

 in these lesions, and it can be cultivated, though with diffi- 

 culty, and when inoculated will reproduce the disease. It, or 

 an organism morphologically indistinguishable from it, occurs 

 sometimes in ulcers following herpes preputialis, though of 

 unusual severity; possibly in these cases the bacilli are less 

 virulent than in the ordinary soft sore. It is scarcely neces- 

 sary to say that syphilis and soft sore (or gonorrhoea and soft 

 sore) may be inoculated at the same time, and the lesions 

 appropriate to both diseases may be present simultaneously. 



The bacillus in question is a short straight rod, less than a 

 quarter the length of the tubercle bacillus, and not much 

 longer than the bacillus of influenza, and is frequently 



* But sores which are very similar in appearance may be due to ordinary 

 eptic organisms. 



