SYSTEMATIC AND DESCRIPTIVE. 32.1 



serum, threads develop, consisting of both rods and 

 cocci. From blood-serum they can be cultivated 

 on nutrient gelatine, and vegetable albumen. 



Cultivation does not deprive the micro-organism 

 of its virulence, but heating the spores to 85 C. 

 renders them harmless. 



Inoculation in the subcutaneous tissue of guinea- 

 pigs, rabbits, calves, and sheep proves fatal. 

 White rats, dogs, and fowls have an immunity t 

 Injection into the veins in small quantity produces 

 a febrile disorder, in larger quantities death. 

 Animals in the former case suffer an abortive ill- 1 

 ness, which protects them against further inocula^ 

 tion. The micro-organism is the cause of a disease 

 in cattle, "blackleg" " quarter- evil" or " Rausch- 

 brand" At the autopsy the micro-organisms are 

 found in the subcutaneous connective tissue, in 

 the lymph glands, kidneys, spleen, and lungs. 

 An irregular tumour is formed in the skin, which 

 develops rapidly, and gives crepitus on palpation. 

 The tumour, which is hsemorrhagic effusion, occur- 

 ring in the extremities, impedes the animal's move- 

 ments. The cattle infected die in thirty-six to 

 forty-eight hours. 



GROUP III. LEPTOTRICHE^E. 



Genus I. Crenothrix. Threads articulated ; cells 



sulphurless ; habitat water. 

 Genus II. Beggiatoa. Threads unarticulated ; cells 



with sulphur granules ; habitat water. 



21 



