294 VETERINARY BACTERIOLOGY 



The bacteria belonging to this group are closely related in their 

 morphologic, physiologic, and cultural characters. A descrip- 

 tion for one will answer in general for the remaining. They are 

 small, plump, short bacilli, with rounded ends, usually about 

 0.5 to 0.8 by 1 to 2 //, non-motile, and without spores. Capsules 

 may be demonstrated in the blood with some species. The organ- 

 isms stain readily with aqueous anilin dyes, but are gram-negative. 

 The outstanding morphologic character is the tendency toward 

 bipolar staining, particularly in tissues. The ends stain deeply, 

 the central portion not at all, giving the appearance of diplococci. 

 The organisms grow readily upon the common cultural media, 

 with the exception of potato, upon which they usually develop 

 scantily, if at all, at blood-heat. Gelatin is not liquefied. Some 

 acid is produced from dextrose; milk is usually not coagulated. 

 The organisms are not particularly resistant, and are easily des- 

 troyed by heat, desiccation, and sunlight. Not only the organ- 

 isms, but the diseases produced by them in various animals, 

 resemble each other. All the species of the group are pathogenic 

 for the rabbit, and usually for other laboratory animals. On the 

 other hand, some of them possess a high degree of specificity, 

 such that only that form isolated from the lesions of a certain 

 species is pathogenic for that species. The disease is, in most 

 cases, a true septicemia, characterized by hemorrhages in various 

 organs. In some cases it may be localized in the lungs, the lymph- 

 glands, or the intestines. 



As has been stated, it is at present not possible to differentiate 

 the organisms associated with the various diseases from each other 

 by any of their biologic characters. It is, therefore, necessary 

 to adopt tentatively a pathologic classification, and group them 

 with reference to the animals naturally infected and the diseases 

 produced. The following list includes only the/ more important 

 types that have been described, and is not complete: 



A. Hemorrhagic septicemias of lower animals only. 



1. Of birds, Bacillus avisepticus. 



2. Of swine, Bacillus suisepticus. 



3. Of cattle, Bacillus bovisepticus. 



4. Of equines, Bacillus equisepticus* 



5. Of rabbits, Bacillus cuniculicida. 



