BACTERIUM MALLEI 449 



larities in the way that it takes up the dyes, being usually 

 marked by deeply stained areas that alternate with points 

 at which it either does not stain at all or only slightly. 



The animals susceptible to infection by this organism are 

 horses, asses, field-mice, guinea-pigs, and cats. Baumgarten 

 records cases of infection in lions and tigers that were fed, 

 in menageries, with flesh from horses affected with the 

 disease. Rabbits are but slightly susceptible; dogs and 

 sheep still less so. Man is susceptible, and infection not 

 rarely terminates fatally. Wl^ite mice, common gray house- 

 mice, rats, cattle, and hogs are insusceptible. 



Inoculation Experiments. — ^The most favorable animal 

 upon which to study the pathogenic properties of this 

 organism in the laboratory is the common field-mouse. 

 When inoculated subcutaneously with a small portion of a 

 pure culture of bacterium mallei death ensues in about 

 seventy-two hours. The most conspicuous tissue-changes 

 will be enlargement of the spleen, which is at the same time, 

 almost constantly, studded with minute gray nodules, the 

 typical glanders nodule. They are rarely present in the 

 lungs, but may frequently be seen in the liver. From these 

 nodules the glanders bacillus may be obtained in pure culture. 

 With the exception of the characteristic nodules, the disease 

 as seen in this animal presents none of the features that 

 it displays in the horse and ass. The clinical and patho- 

 logical manifestations resulting from inoculation of guinea- 

 pigs are much more faithful reproductions. The animal 

 lives usually from six to eight weeks after inoculation, and 

 during this time becomes affected with a group of most 

 interesting and peculiar pathological processes. The specific 

 inflammatory condition of the mucous membrane of the 

 nostrils is almost always present. The joints become swollen 

 29 



