334 PATHOGENIC BACTERIA. 



cooled to 50 C. with the appropriate material, and mix- 

 ing with it about 2 c.cm. of blood withdrawn from a vein 

 of the arm with a sterile hypodermic syringe. The blood- 

 agar mixture is poured into a sterile Petri dish and set 

 aside for a day or two at 37 ° C. The colonies that form 

 are to be examined for bacilli that resist decolorization 

 with acids. 



Novy mentions bacilli which are occasionally found in 

 milk, butter, timothy hay, cow-dung, etc., which stain 

 like the tubercle bacillus and may be mistaken for it. 

 Guinea-pig inoculations must be resorted to in cases of 

 doubt, but as some of these organisms sometimes kill the 

 guinea-pigs after a month or two, and as small nodules 

 or tubercles may be present in the animals in the mesen- 

 tery, peritoneum, liver, lung, etc., the diagnosis may have 

 to be subjected to the further confirmation of a histolog- 

 ical examination of the lesions in order to exclude tuber- 

 culosis. In cases of this kind it should not be forgotten 

 that the tubercle bacillus can be present in the substances 

 mentioned, so that the exact differentiation becomes a 

 very fine one. 



Acid-resisting bacilli are also said by Novy to occur 

 upon the conjunctiva. 



Pseudo-tuberculosis. — Eberth, Chantemesse, Charrin, 

 and Roger have reported certain cases of so-called pseudo- 

 tuberculosis. The disease occurred spontaneously in 

 guinea-pigs, and was characterized by the formation of 

 cellular nodules in the liver and kidneys much resembling 

 miliary tubercles. Cultures made from them showed the 

 presence of a small motile bacillus which could easily be 

 stained by ordinary methods (Fig. 71). When introduced 

 subcutaneously into guinea-pigs the original disease was 

 produced. 



The Bacillus pseudo-tuberculosis is characterized by 

 Pfeiffer as follows : The organism is rod-shaped, the rods 

 varying in length. Upon gelatin and agar-agar circular 

 colonies with a dark nucleus surrounded by a transparent 

 zone are found. In gelatin punctures the bacilli grow all 



