BUBONIC PLAGUE. 439 



adrenals congested. There are often sero-sanguinolent 

 effusions into the serous cavities. 



Klein l states that the intraperitoneal injection of the 

 bacillus into guinea-pigs is of diagnostic value, produc- 

 ing in twenty-four to forty-eight hours a thick cloudy 

 peritoneal exudate rich in leukocytes and containing 

 characteristic chains of the plague bacillus. 



Animals fed upon cultures or upon the flesh of other 

 animals dead of the disease became ill and died with 

 typical symptoms. When Klein inoculated animals with 

 the dust of dwelling-houses in which the disease had 

 occurred, some died of tetanus, one from plague. Many 

 rats and mice in which examination showed the charac- 

 teristic bacilli died spontaneously in Hong-Kong. 



Yersiii showed that flies also die of the disease. Mace- 

 rating and crushing a fly in bouillon, he not only suc- 

 ceeded in obtaining the bacillus from the medium, but 

 infected an animal with it. 



Nuttall, 2 in reviewing Yersin's fly-experiment, found 

 the statement true, and showed that flies fed with the 

 cadavers of plague-infected mice died in a variable 

 length of time. Large numbers of plague bacilli were 

 found in their intestines. He also found that bed-bugs 

 allowed to prey upon infected animals took up large 

 numbers of the plague bacilli and retained them for a 

 number of days. These bugs did not, however, infect 

 healthy animals when allowed, subsequently, to feed 

 upon them. Nuttall is not, however, satisfied that the 

 number of his experiments upon this point was great 

 enough to be conclusive. 



Ogata found that the plague bacillus existed in the 

 bodies of fleas found upon diseased rats. One of these 

 he crushed between sterile object-glasses and introduced 

 into the subcutaneous tissues of a mouse, which died 

 in three days with typical lesions of the plague, a con- 

 trol-animal remaining well. Some guinea-pigs taken 



1 Centralbl. f. Bakt. u. Parasitenk., xxi., No. 24, July 10, 1897, p. 849. 



2 Ibid., Aug. 13, 1897. 



