MICROCOCCUS LANCEOLATUS. 505 
culture of the micrococcus, usually results in the death 
of these animals in from twenty-four to forty-eight 
hours. The course of the disease produced and the 
post-mortem appearances indicate that it is a form of 
septicemia—what is known as sputum septicemia. 
After injection there is loss of appetite and great 
debility, and the animal usually dies some time during 
the second day after inoculation. The post-mortem 
examination shows a local reaction, which may be of 
a serous, fibrinous, hemorrhagic, necrotic, or purulent 
character; or there may be combinations of all of these 
conditions. The most marked pathological lesion is 
the enlargement of the spleen, which in mice is con- 
spicuous and common, and in rabbits not so much so. 
It is sometimes hard, dark colored, and dry, or it may 
be soft and bright red. The liver also is sometimes 
dark colored and gorged with blood, but more fre- 
quently it is paler than normal and rich in fat. The blood 
of inoculated animals immediately after death often 
contains the micrococci in very large numbers. For 
microscopical examination they may be obtained from 
the blood of the veins, arteries, or cavities of the heart, 
and usually from the pleural and peritoneal exudations 
when they are present. 
Mice and rabbits are the most susceptible animals, 
and are thus usually employed for experimental pur- 
poses in investigations with this micrococcus; but 
guinea-pigs, dogs, cats, rats, and sheep are also sus- 
ceptible. Chickens and pigeons are insusceptible. 
Young animals, as a rule, are more easily affected 
than old ones. In dogs subcutaneous injections usually 
give negative results. True localized pneumonia does 
not usually result from subcutaneous injections into 
