146 MEDICAL BACTERIOLOGY 



usually without, involvement of the lungs, and the pneumonic form, dis- 

 tinguished by the occurrence of pneumonia with slight, or no enlargement of 

 superficial lymph glands. 



In both the bubonic and pneumonic forms of the disease, bacteremia is 

 said to occur; in both bacilli are present in the lymph glands and may be in the 

 urine. 



If the bubonic form is complicated with pneumonia bacilli may occur in the 

 sputum. Jn the pneumonic form bacilli are regularly present in the sputum in 

 large numbers, from the onset throughout the disease. 



Diagnosis. Microscopic examination of the sputum in pneumonic cases 

 discloses the cause. 



For the diagnosis of suspected and bubonic cases lymph glands are searched 

 for, massaged and some of their contents removed with a sterile syringe and 

 needle. A portion of the material so obtained is planted on salt-agar, in bouillon 

 containing oil and in MacConkey's bile-salt medium; about 3^0. to Y cc. is 

 injected subcutaneously into a guinea-pig, smears are made, fixed and stained 

 with carbolfuchsin, others with methylene blue and still others by Gram's 

 method. 



The discovery of a polar staining cocco bacillus in the smears, involution 

 forms on salt-agar after 24 hours at 37C., death of the inoculated animal and 

 recovery from its body of organisms identical with those removed from the 

 gland establishes the diagnosis. 



When examining rats, in addition to making blood cultures, and subcultur- 

 ing these on glucose, lactose, saccharose and salt-agar, careful examination of 

 the spleen and liver should be made to detect characteristic changes, produced 

 by plague. 



