348 AGRICULTURAL AND INDUSTRIAL BACTEKIOLOGY 



the pericardium. The liver is usually congested and shows 

 small hemorrhages. The spleen is enlarged and softened 

 and usually numerous petechial hemorrhages are to be 

 found in the internal organs and the mucous and serous 

 membranes. 



Practical methods of immunization against the disease 

 have not been developed, although there has been much 

 experimental work done. The disease apparently is trans- 

 mitted from bird to bird by ingestion of food or water 

 fouled with excretions which contain the specific causal 

 organism. The only practicable method of control appar- 

 ently is careful sanitation. 



PASTEURELLA BOVISEPTICA 



Synonyms. Bacterium bovisepticum, Bacillus lovisepti- 

 cus, Bacillus bipolare multicidum, Bacillus bovicida, Bacil- 

 lus vitulisepticus. 



The disease hemorrhagic septicemia is one of the most 

 widely distributed in the United States. Similar diseases 

 have been described in European countries, both in domestic 

 cattle and wild animals, particularly the deer. The disease 

 in cattle is characterized by a fever due to the development 

 of the causal bacteria throughout the blood stream and in 

 the tissues. Upon post mortem, the animal generally shows 

 large numbers of hemorrhagic spots or points in the internal 

 organs and in some cases under the skin. These hemor- 

 rhages are particularly characteristic of the serous mem- 

 branes. In some cases the hemorrhages in the subcutaneous 

 tissues may be quite extensive and cause darkening of the 

 skin. 



It is possible to immunize animals by the injection first, of 

 nonvirulent and later of virulent organisms, and the serum 

 from such animals is known to have the power of producing 

 passive immunity. It is evident, however, that there are 

 many different strains of bacteria belonging to this species 



