410 MICRO-ORGANISMS IN WATER 



TYPHOID BACILLUS 



Authority. Eberth, Virchow's Archiv, vol. Ixxxi., 1880; also ibid. vol. 

 Ixxxiii., 1881. Gaffky, ' Zur Aetiologie des Abdominaltyphus,' Mittheilungen 

 a. d. kaiserlichen Gesundlieitscuntc, vol. ii., 1884, p. 372. 



Where Found. In the blood, urine, faeces, as well as in the organs of typhoid 

 patients. Found by numerous investigatoi's in water. 



Microscopic Appearance. A short, plump bacillus about three times as 

 long as broad, with rounded ends. It occurs in the tissues usually singly, but 

 in artificial cultures it grows frequently into long threads. It is very motile 

 and is provided with numerous cilia, which are attached to both the sides and 

 ends of the bacillus. To stain the cilia add 22 drops of caustic soda to 

 16 c.c. of the mordant (Loeffler) (see p. 56). It is not stained by Gram's 

 method, and stains less readily with aqueous aniline solutions than most bac- 

 teria. Giinther recommends heating the cover-glass, after the dye has been 

 poured on it, for a few seconds until it begins to steam, and then washing off 

 the stain as usual. It does not form spores. 



Cultures. 



GELATINE PLATES. The colonies on the surface form large spreading greyish 

 white iridescent expansions with jagged and irregular edge. Under a low power 

 they exhibit a brownish shimmer and a characteristic woven structure. The 

 depth colonies are darker, with regular edge, and are covered with delicate irre- 

 gular lines. No liquefaction takes place. 



GELATINE TUBES. Grows chiefly on the surface, producing a delicate greyish 

 white iridescent expansion with irregular edge. 



AGAR-AGAR. Forms a greyish white moist expansion. 



POTATOES. Produces an almost invisible greyish white growth after forty- 

 eight hours, but on touching the moist-looking surface with the needle a tough 

 resistant pellicle is found. On different potatoes, however, its growth is more 

 apparent, so that the above is not the only appearance to which it gives rise. 



BLOOD SEBUM. Produces a milk-white expansion restricted to the path of 

 the needle. 



BKOTH. Kenders it turbid. 



MILK. Grows abundantly, rendering it slightly acid. No coagulation takes 

 place. 



Remarks. It grows best at about 37 C. Kitasato states that it pi-oduces no 

 indol reaction (see p. 273). It produces sulphuretted hydrogen in iron-gelatine (see 

 p. 14), the needle-track after from five to six days becoming intensely black in 

 colour. In iron-agar, at from 33 to 34 C., this black colour appears at the end of 

 twenty-four hours (Fromnie). It produces sulphuretted hydrogen in broth with or 

 without peptone ; comparative tests made with the B. coli-communis revealed no 

 difference either in the degree of the reaction (as shown by the lead-paper test) or in 

 the rapidity with which it took place in the case of these two organisms. The typhoid 

 bacillus never produces gas in any artificial media (see p. 269). It is destroyed when 

 heated for ten minutes at 60 C. Injection into the aural vein of rabbits causes death 

 in twenty-four to twenty-eight hours (I'Yaenkel and Simmonds) ; guinea-pigs into 

 which the cultures are introduced by the mouth, as described for cholera, ai*e also 

 killed (Seitz). Opinion is, however, still divided as to whether death is due to mere 

 intoxication by the bacterial products present in the cultures or to actual multipli- 

 cation of the bacillus within the animal. In this connection see Petruschky 

 (Zeitschr. f. Hygiene, vol. xii., Ls'.i-J, p. -jr,'.)). For the effect of insolation on this 

 bacillus see Chapter IX. It will not grow in formalin-broth (1 : 70001, see p. '-2*.~>. 



