576 Bacilli Resembling the Typhoid Bacillus 



Staining. It stains irregularly with the ordinary solu- 

 tions, but not by Gram's method. It has no spores. 



Cultivation. Upon gelatin plates it forms round, pale 

 gray, translucent colonies. It does not liquefy the gelatin. 

 The deep colonies are brown and spheric. The growth on 

 agar-agar is similar to that of the colon bacillus. The 

 organism produces no indol, coagulates milk in a few days, 

 and reduces litmus. Its fermentative powers have not been 

 sufficiently studied. Upon potato it forms a yellowish- 

 white, shining layer. 



Pathogenesis. The bacillus is pathogenic for mice, 

 guinea-pigs, pigeons, lambs, and kids, but not for dogs, 

 cats, rats, or sparrows. The infection may be fatal for 

 mice and guinea-pigs, whether given subcutaneously, intra- 

 peritoneally, or by the mouth. 



Lesions. The bacilli are found scattered throughout the 

 organs in small groups, resembling those of the typhoid 

 bacillus. 



At the autopsy a marked enteritis and swelling of the 

 lymphatic follicles and patches, with occasional hemor- 

 rhages, are found. The bacilli occur in the intestinal con- 

 tents. The spleen is somewhat enlarged. 



The bacillus is differentiated from the colon bacillus 

 chiefly by the absence of indol-production, by its ability to 

 produce infection when ingested, and by the fact that it 

 elaborates a toxic substance capable of producing symp- 

 toms similar to those seen in the infection. 



It may be distinguished from Bacillus lactis aerogenes 

 by its motility. It is with great difficulty separable from 

 certain water bacteria; but so far as is known its patho- 

 genesis can be made use of for assisting in its differentiation 

 in doubtful cases. 



BACILLUS DYSENTERIC (SHIGA). 



General Characteristics. A motile, flagellated, non-sporogenous, 

 non-liquefying, aerobic and optionally anaerobic, non-chromogenic, 

 non-aerogenic, pathogenic bacillus of the intestine, staining by ordi- 

 nary methods, but not by Gram's method. 



After considerable investigation of the epidemic dysentery 

 prevalent in Japan, Shiga * has come to the conclusion that 

 a bacillus which he calls Bacillus dysenteriae is its specific 

 cause. 



* "Centralbl. f. Bakt. u. Parasitenk.," 1898, xxiv, Nos. 22-24. 



