MICROBIAL DISEASES OF MAN AND DOMESTIC ANIMALS 825 



sometimes shows polar staining, and is Gram-negative. The temperature range is 

 about 26 to 41 C. It is aerobic. Haemoglobin is usually regarded as an essential 

 constituent of media for its growth. Superheated or boiled blood agar affords more 

 luxuriant growth than agar containing unaltered blood. Colonies are small, round, 

 and transparent and remain discrete unless thickly sown. Growth occurs in blood 

 broth used in thin layers. Resistance is less than the majority of non-spore-bearing 

 bacteria. It seems especially sensitive to drying and its thermal death point is 

 60 C. for about one minute. The bodies of the bacteria are distinctly pyogenic. In- 

 oculated animals develop agglutinins and complement-fixing antibodies which 

 are useful for identification purposes. Some influenza patients give positive com- 

 plement fixation tests with antigens of B. influenza, but the same may be said of 

 antigens of streptococci, and pneumococci. There are probably different strains of 

 B. influenza as in the case of pneumococci. 



WHOOPING COUGH* 



Bacterium pertussis 



According to latest statistics, the death-rate of whooping cough is 

 roughly about 5.5 per 100,000 exposed. The causative agent, accord- 

 ing to Bordet and Gengou, is an influenza-like bacillus. 



It is a non-motile coccoid bacillus, stained faintly by aniline dyes 

 and Gram-negative. It is distinguished from the influenza bacillus by 

 agglutination and complement deviation tests and by the fact that it 

 can be gradually adapted to ordinary media. 



The production of pertussis in young animals has been claimed. 

 The organism has an endotoxin which produces local necrosis after 

 subcutaneous injection. 



Further evidence on the etiology of whooping cough is afforded 

 by the observations of Mallory and others who have found large num- 

 bers of small microorganisms corresponding morphologically with 

 Bact. pertussis occurring between the cilia on the epithelial cells lining 

 the respiratory tract in fatal cases of the disease. 



H^MORRHAGIC 



Bacterium bomsepticum 



Haemorrhagic septicaemia belongs to a class of similar diseases 

 grouped under the general head of Pasteur elloses. 



* Prepared by Edward Fidlar. 

 t Prepared by M. H. Reynolds. 



