DIPHTHERIA VITULORUM 169 



Microscopical Appearances. Bacilli five or six times as long as 

 broad, usually in filaments. 



Biological Characteristics. This bacillus does not grow in 

 nutrient gelatine blood serum from sheep and other usual media, but 

 in the blood serum of calves pieces of the affected tissue gave a whitish 

 growth of the bacillus, which, however, did not grow when transferred 

 afresh to serum. 



Pathogenesis. Fatal for mice in from seven to thirty days when 

 inoculated subcutaneously, the autopsy revealing extensive infiltration 

 of abdominal walls, which often spreads into the peritoneal cavity, 

 enveloping the viscera in a yellowish exudation. The bacilli are formed 

 in this exudation, and mice inoculated with some of the fluid die 

 similarly. Non-pathogenic for rabbits and guinea-pigs. 



BACILLUS TYPHI ABDOMINALIS. 



(Bacillus of Typhoid Fever.) 



This organism was first observed by Eberth in the internal organs 

 of typhoid cadavera. Koch also saw the bacillus about the same 

 time, and photographed it. It was first obtained in pure cultures by 

 Gaffky, and has also been found during life in the blood, urine, and 

 faeces of typhoid patients. 



Microscopical Appearances. Short, plump rods with rounded 

 ends, 1 to 3 ft long, and 0'5 to 0'9 /* broad, which in sections of tissue 

 are usually found singly, but in cultures often found in long threads. 

 (See Photomicrograph, Fig. 62.) In agar cultures at 37 C., in the 

 bodies of animals, and in human tissues, the rods are more plump, and 

 smaller in all directions than on gelatine and potato media, and the long 

 threads occur more frequently at lower temperatures. 



Motility. Actively motile, each bacillus possessing eight to eighteen 

 flagella situated along the sides and ends (Peritricha). (See Photo- 

 micrograph, Plate II., Fig. 7, stained by the author's orcein method ; also 

 the same preparation x 1500 diameters, Plate II., Fig. 8.) 



Spore Formation does not exist. The so-called spores of Gaffky 

 are, according to later investigations, involution forms. 



Staining Reactions. With the ordinary aniline dyes the rods do 

 not stain so readily as most other organisms. Watery solutions of the 

 dyes and a weak solution of carbol fuchsin give the best results when 

 slightly heated during the staining process. They do not stain by the 

 Gram method. Small vacuoles are sometimes present in the rods, due 

 to retraction of the protoplasm from the cell envelope of the bacilli. 



