200 DYSENTERY, HOG AND CHICKEN CHOLERA. 



Morphology. The Bacillus dysenteries is of medium size, 

 with round ends, containing no spores. The flagellate char- 

 acter and motility of the B. dysenterise have been denied by 

 many observers. It stains by the ordinary anilin dyes, but 

 not by Gram's method. 



Biologic Characters. It is aerobic, but may be grown with- 

 out oxygen. It grows at the ordinary room temperature, but 

 best at the temperature of the human body, and does not 

 liquefy gelatin. 



Its growth on agar is not characteristic, slightly resembling 

 the typhoid growth, and on gelatin the growth is pearl col- 

 ored, somewhat like the typhoid, but later becomes moist. 

 On potato it sometimes has also an invisible growth ; at other 

 times its growth is rather voluminous and grayish brown in 

 color. It clouds bouillon without forming a pellicle on the 

 surface. It does not liquefy blood-serum. Litmus milk at the 

 end of three days becomes of a pale lilac color, but the milk 

 is not coagulated. In six or seven days the medium becomes 

 dark blue. It produces no indol. By means of fermentation 

 tests Hiss has divided the dysentery 'bacilli into four groups : 

 Group I. ferments only dextrose. Group II. ferments dex- 

 trose and mannit. Group III. ferments dextrose, mannit, 

 and saccharose. Group IV. ferments dextrose, mannit, mal- 

 tose, saccharose, and dextrin. None of these groups liquefy 

 gelatin. None are capable of forming acid from lactose and 

 none produce gas in carbohydrate media. 



Agglutination. The serum of affected animals has an 

 agglutinating power on young cultures of the bacillus. By 

 agglutination methods group differentiation has been proved. 



It is pathogenic for laboratory animals. When injected 

 intraperitoneally into animals it produces a purulent peri- 

 tonitis, with involvement of the mesenteric glands and swollen 

 spleen, and the liver is covered with an exudate. The intes- 

 tinal glands and Peyer's patches show signs of inflammation. 

 The bacillus may be recovered from the exudate, and also in 

 limited quantity from the organs. Subcutaneous injections 

 show swelling and oedema at the point of inoculation, with 



