MICROBIAL DISEASES OF MAN AND DOMESTIC ANIMALS 789 



mum of 37 and a maximum of 42. Its atmospheric requirements are 

 those of an aerobe. 



On serum agar the colonies are small, grayish and glistening, with 

 smooth outline and granular center. On legumin-agar they are 

 round, hemispherically raised, and opalescent. In broth growth is 

 slow and occurs at the surface. Only rarely is growth obtained on 

 gelatin media chiefly because of the unfavorable temperature required. 

 There is no change in litmus milk. Acid is formed from dextrose and 

 maltose. 



The toxins of the meningococcus are probably intracellular. 



The resistance of the organism to unfavorable conditions is very 

 slight, and it undergoes autolytic changes almost with the same rapidity 

 as does the gonococcus. 



Meningitis due to this coccus does not occur naturally in animals, 

 but it has been produced in monkeys artificially. Laboratory animals 

 inoculated subcutaneously, intraperitoneally or intravenously with a 

 sufficiently large dose will die without developing meningitis. 



Animals immunized by graded doses show specific agglutinins, 

 opsonins and lysins. Horses so treated yield a serum which in some 

 hands has given very favorable results. In the first epidemics in the 

 British armies however, the mortality ranged from about 40 to 50 per 

 cent and the serum was distinctly disappointing. Investigation then 

 demonstrated that four types of the meningococcus existed, distin-- 

 guishable by agglutination reactions, and new sera were produced which 

 yielded better results. 



As the germs leave the body in the discharges of the nose and mouth, 

 the prevention and control of the disease would appear at first thought 

 to be an easy matter, but the occurrence of carriers and ignorance of 

 the factors which govern the virulence of the infective agent and the 

 individual's susceptibility make epidemic meningitis a very difficult 

 problem from the standpoint of public health. 



INFECTIOUS MASTITIS* 



Infectious mastitis or mammitis (inflammation of the udder) 

 appears in isolated outbreaks and is serious for the individual owner and 

 individual herd, but it never spreads widely. It may affect a large 

 portion of the herd and cause heavy financial losses. Infectious masti- 



* Prepared by M. H. Reynolds. 



