DIPHTHEROID BACILLI 89 



on, in subculture, there may be no staining of the polar bodies. Neisscr originally 

 recommended five seconds' application, with an intermediate washing, for each of 

 his two solutions. Thirty seconds for each is probably preferable. Some authorities 

 recommend five to thirty minutes. It is well to bear in mind that about 2% of the 

 people in apparent health carry diphtheria bacilli of the granular or barred type in 

 their throats and of these about one in five will prove virulent for the guinea-pig. 



It is essential when a question exists as to the nature of a diphtheria- 

 like organism to test it as to virulence. While there are exceptions, 

 especially in freshly isolated colonies, yet as a rule a severe infection 

 yields virulent organisms and vice versa. Pure cultures are best obtained 

 by streaking material from the throat on glycerine agar plates. From 

 an isolated colony inoculate a tube of bouillon. From such a twenty- 

 four-hour-old culture inoculate a guinea-pig with two or three drops 

 subcutaneously in the shaven abdomen. Escherich considers a fatal 

 result with 1.5 c.c. of such a bouillon culture a satisfactory test as to 

 virulence. After death, which occurs in two or three days, the adrenals 

 are enlarged and haemorrhagic. 



Diphtheroid Bacilli. Pseudodiphtheria Bacillus. Hofman's Bacil- 

 lus. Under these terms various Gram positive bacilli have been de- 

 scribed as occurring in nose and in skin diseases. 



Their chief importance is in connection with their presence in the 

 throats of healthy people. Probably approximately 10% of people 

 harbor such organisms as against i to 2% with granular types. Some 

 authorities believe it possible for these diphtheroids to be capable of 

 being transformed into virulent diphtheria bacilli. This seems im- 

 probable. Such organisms are often found in urethral discharges, 

 either alone, or with gonococci or other organisms. 



1. They very rarely give the blue dot staining at the two ends. Exceptionally 

 they may give a dot at one end. Neisser attaches importance to the dots 

 at both ends as showing diphtheria. 



2. They tend to stain solidly or at most with only a single unstained segment. 

 They are shorter, thicker, and do not curve so gracefully as the true diphtheria 

 bacillus. They are stockier. 



3. They produce very little acid in sugar media, not one-half that produced by 

 true diphtheria. 



4. They are nonpathogenic for guinea-pigs. 



5. Many of them grow quite luxuriantly and often show chromogenic power. 



Xerosis Bacillus. This organism is frequently found in normal 

 conjunctival discharges. There is question as to its pathogenesis, and 

 the finding of this organism should not exclude the previous presence of 



