204 CLINICAL BACTERIOLOGY. 



tures that have already been carried on artificially for sev- 

 eral years. The animals then die in the course of the 

 second week, and one or more glands, up to the size of a 

 walnut, are found, which contain creamy pus in their cen- 

 tral portions, in which plague-bacilli are present in large 

 numbers. An involuntary experiment in the human being 

 is also on record : A member of the German Plague-com- 

 mission suffered infection in making an autopsy of a body 

 dead of plague. Two days later a small pustule formed on 

 the right hand, followed shortly by a lymphangitis, and a 

 swollen gland in the axilla. The discharge from the pus- 

 tule contained plague-bacilli. In spite of the alarming 

 character of the disease at first, recovery took place. 



Etiologic Relations of the Bacilli to Plague. The con- 

 stant presence in all cases of plague and the positive out- 

 come of experiments on animals indicate with certainty that 

 the plague-bacillus is the specific exciting agent of plague. 

 In accordance with what has been said, the disease is to be 

 looked upon rather as an infectious disease ; but a toxic 

 element is by no means wanting. The hyperemia and the 

 ecchymoses of the stomach and the bowel are considered 

 by the German Plague-commission as purely toxic effects. 

 As an evidence of the toxic action, the case is reported of 

 a fetus born on the third day of the disease in the mother, 

 in which the characteristic hemorrhages were found, al- 

 though all portions of the body were free from germs. 

 Certain sequelae also are to be attributed to the toxic 

 effects : paralysis of the recurrent laryngeal nerve, amauro- 

 sis, aphasia, deafness, paraplegia, etc. The poison of the 

 plague-bacilli is probably contained within the bodies of 

 the bacteria. The German Commission dried cultures 

 carefully, mixed them with water, and heated them to a 

 temperature of 65 C. (149 F.). As much as eighty 

 milligrams of the dry residue were introduced into the 

 peritoneal cavity of brown apes, which exhibited only mild 

 manifestations of disease, slight decline of temperature, 

 want of energy, and anorexia. In brown apes, which are 

 by no means so susceptible to plague as gray apes, this 

 toxic effect is, therefore, but little marked. 



Bacteriologic Diagnosis of Plague. The suppurating 

 plague-buboes contain the characteristic bacteria in enor- 

 mous number. These are readily recognized by their polar 

 staining when treated with methylene-blue. A similar 



