370 THE TYPHOID BACILLUS 



unaffected but a few of them towards the end of the first week had a rise of 

 temperature, became emaciated, suffered from diarrhoea and eventually 

 died. Post mortem, examination showed ulceration of Peyer's patches, 

 enlargement of the spleen, etc. The typhoid bacillus was recovered in pure 

 culture from the spleen. 



Chantemesse and Ramond lowered the resistance of rabbits by injecting 

 into the peritoneal cavity some sterile broth containing 50 drops of laudanum 

 and then a quarter-of-an-hour later introduced into the stomach by means 

 of a tube 5 c.c. of a young broth culture of the typhoid bacillus. Animals 

 so treated became infected with a true enteric fever ; they developed the 

 characteristic lesions, and their serum agglutinated the bacillus. 



By daily inoculation with human blood serum or urine for a period of 

 3 weeks animals can be rendered more susceptible to infection with the 

 typhoid bacillus. 



SECTION II. MORPHOLOGY. 

 1. Microscopical appearance. 



The typhoid bacillus occurs in the tissues as a short rod measuring about 

 2-3/x long and 0'6-0'7/x broad. 



In cultures its length and breadth vary within wide limits. In broth, for example, 

 the bacillus is shorter and more slender ; in old gelatin cultures, it is elongated and 

 shows filamentous forms ; on agar and potato it is broader and shorter and has 

 a squat appearance. 



The bacilli both in tissues and cultures occur singly or joined together in 

 pairs, and in young cultures they not infrequently look like diplococci. 



The ends of the bacilli are rounded. 

 The protoplasm stains uniformly, but 

 occasionally, in old cultures, the bacilli are 

 somewhat swollen about their centres and 

 show a clear space of variable size " the 

 shuttle form " of Artaud. This unstained 

 portion does not represent spore formation 

 any more than do the terminal swellings 

 which are sometimes seen in cultures of 

 the bacillus and which are merely de- 

 generation forms. 



As a rule, the typhoid bacillus is very 

 motile and moves rapidly across the field 

 of the microscope like fish in water, but 

 some strains of the bacillus are only slightly 

 FIG. 216. Film preparation of the typhoid motile. The motility is due to the pre- 

 bacillus from a gelatin culture. Carbol- f a / . / / N 



fuchsin. (Oc. 2, obj. / 2 th, Zeiss.) sence ol nagella (vide infra). 



If a trace of growth from a solid medium 



be placed in a drop of water the bacilli separate one from another and the 

 water is immediately rendered turbid (Chantemesse). 



Staining reactions. The typhoid bacillus stains readily with the basic 

 aniline dyes and is gram-negative. 



Staining of flagella. The nagella may be easily stained (p. 149). Van 

 Ermengem s or Nicolle's method is recommended as giving the best results. 



In stained films the number and arrangement of the flagella can be readily 

 made out. As a rule, each bacillus has eight to a dozen flagella, but it is not 

 at all uncommon for individual bacilli to have as many as eighteen to 

 twenty-four. Flagella which have been inadvertently torn away from 



