TYPHOID 143 



three days' incubating at- blood-heat, the gelatine shake 

 culture after three days at about 20° C. 



It is worthy of note that in gelatine streak cultures 

 typhoid has a tendency to be confined to the inoculation 

 streak, while the growth in the case of the Bacillus coli com- 

 munis spreads all over the nutrient medium. 



As a further means of distinction, the Bacillus typhosus 

 and Bacillus coli communis are amongst the limited number 

 of organisms that can grow on media that contain small 

 quantities of phenol (carbolic acid). These two organisms 

 will grow in gelatine or broth containing 0'05 per cent, of 

 phenol, whereas the growth of the other pathogenic and 

 putrefactive bacteria is inhibited. 



Pseudo-Typhoid Organisms. — A number of organisms have 

 been described by Cassedebat, Babes, Booker, Klein, 

 Springthorpe and others, which were obtained from cases 

 which were clinically identical with enteric fever and other 

 sources, which resembled the Eberth-Gaffky bacillus, but 

 were shown to present slight but constant differences in 

 their cultural characters. 



They are only to be differentiated from the true typhoid 

 bacillus by a very careful comparison of cultures made side 

 by side on various media. 



Cassedebat found three species of pseudo-typhoid bacilli 

 in the Marseilles water-supply during the great typhoid 

 epidemic in that town during 1891. They all corresponded 

 with the E berth - Gaffky bacillus in their growth upon 

 gelatine, potato, blood serum, etc., and they all gave a 

 negative indol reaction. Like the typhoid bacillus, they 

 grew in milk without causing the coagulation of the caseine, 

 but two of them produced an alkaline reaction in this 

 medium, while the third corresponded with the Eberth- 

 Gaffky bacillus in producing a decided acid reaction. 



Occurrence and Distribution. — Admitting typhoid fever to 



