DYSENTERY. 181 



Morphology. The Bacillus dysentericce is of medium size, 

 with round ends, containing no spores, and having flagella. 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 causes no fermentation, though it causes a slight 

 increase of acidity in glucose-bouillon. 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. 



Agglutination. The serum of affected animals has an 

 agglutinating power on young cultures of the bacillus. 



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 o?dema at the point of inoculation, with 

 involvement of the lymphatic glands, and are also followed 

 by effusion in the serous cavities. 



By alkalinizing the secretions of the stomach, animals have 

 been infected by feeding with the bacillus, and in those ani- 

 mals lesions very much resembling the disease in man have 

 been reproduced, and pure cultures of the bacillus obtained 

 from the secretions of the intestines. 



That the poison is in the cell-body of the Bacillus dysen- 

 tencce, and is not a secretion of the cells, is demonstrated by 



