BACILLI OF THE COLON-TYPHOID-DYSENTERY GROUP G49 



as thirty-six days, according to Klein. 10 In ice, according toJPruddeia, 11 

 it may remain alive for three months or over. Against the ordinary 

 disinfectants, the typhoid bacillus is comparatively more resistant 

 than some other vegetative forms. It is killed, however, by 1 : 500 

 bichlorid or 5 per cent carbolic acid within five minutes. 



Pathogenicity. In animals, some early investigators to the con- 

 trary, typhoidal infection does not occur spontaneously and artificial 

 inoculation with the typhoid bacillus does not produce a disease anal- 

 ogous to typhoid fever in the human being. Frankel 12 was able to 

 produce intestinal lesions in guinea-pigs by injection of the bacilli into 

 the duodenum, and recovered the bacteria from the spleens of the animals 

 after death, but the disease produced was in no other respect analogous 

 to typhoid fever in the human being. It is probable that typhoid bacilli 

 injected into animals do not multiply extensively and that most of the 

 symptoms produced are due to the poisons liberated from the dead 

 bacteria. In corroboration of this view is the observation that inocu- 

 lation with dead cultures is followed by essentially the same train of 

 symptoms as inoculation with live cultures. 13 The injection of large 

 doses into rabbits or guinea-pigs intravenously or intraperitoneally is 

 usually followed by a rapid drop in temperature, often by respiratory 

 embarassment and diarrhea. Occasionally blood may be present in 

 the stools. According to the size of the dose or the weight of the 

 animal, death may ensue within a few hours, or, with progressive 

 emaciation, after a number of days, or the animal may gradually recover. 



Welch and Blachstein 14 have shown that typhoid bacilli injected 

 into the ear vein of a rabbit appear in the bile and may persist in the 

 gall-bladder for weeks. Doerr, 15 Koch, 16 Morgan, 17 and more recently 

 Johnston 18 have all confirmed this, the last named showing that 

 the typhoid bacillus could not only remain latent for a long time 

 in the gall-bladder of rabbits, but would appear in the blood 

 stream with considerable regularity after the seventh or ninth day, 

 and persist in the gall-bladder for as long as one hundred and 



10 Klein, Med. Officers' Report, Local Govern. Bd., London, 1894. 



11 Prudden, Med. Rec., 1887. 



12 Frankel, Cent, f . klin. Med., 10, 1886. 



13 Petruschky, Zeit. f . Hyg., xii, 1892. 



14 Welch and Blachstein, Bull. Johns Hop. Hosp., ii, 1891. 



15 Doerr, Centralbl. f. Bakt., 1905. 



16 Koch, Zeitschr. f. Hyg., 1909. 



17 Morgan, Jour, of Hyg., 1911. 



18 Johnston, Jour, of Med. Res., xxvii, 1912. 



