154 BACTERIA 



have been agglutinated do not do so. (Compare Friedberger's 

 idea of infection, page 59.) 



Paratyphoid Bacillus. A pathogenic organism producing all 

 the clinical symptoms of typhoid, only in milder form (at times) has 

 lately been discovered. It differs from the true bacillus because it 

 ferments dextrose and maltose producing gas and acid, and is not 

 agglutinated by the serum from a true typhoidal infection, even in 

 high dilution. Various varieties differ in growth upon litmus milk. 

 In every other respect it resembles the typhoid bacillus, and seems 

 to occupy a position between it and the colon bacillus. Paratyphoid 

 endotoxin resists 60 C. from thirty to sixty minutes, so it is said. 



The Paracolons are organisms like the paratyphoids, but some- 

 what closer to the colon bacillus. (For example, see page 156.) 



Blood cultures are often employed in large hospitals for the diag- 

 nosis of typhoid fever. During the first week of the attack bacilli 

 may be recovered from the blood by withdrawing 10 c.c. of blood 

 from a vein and mixing it with 500 c.c. of bouillon. The large 

 amount of blood is necessary, because the bacilli are few in number, 

 and the bactericidal action of the serum outside the body is powerful 

 until mixed with the bouillon, after which the bacilli are able to 

 withstand it. The bacilli may be easily isolated from the blood by 

 adding the latter to some bile and then incubating it. From the 

 bile, cultures are made in agar or in bouillon. 



COLON BACILLUS. 



Bacterium Coli. 



Bacillus coli or Bacillus coli communis. 



Colon Bacillus. 



While not strictly a pathogenic organism, it plays such an impor- 

 tant part in secondary infection, and resembles so closely the 

 typhoid bacillus, that it will be described here. 



Morphology and Stains. Is not so motile as typhoid; has 

 not so many flagella; and is devoid of spores. It exhibits pleomor- 



