154 STRONG AND TEAGUE. 



cough during the time of exposure, and, notwithstanding the 

 fact that many of the patients suffered with marked dyspnoea 

 and advanced oedema of the lungs, in only a single instance was 

 the plague bacillus encountered in one of these plate-cultures, 

 although in a number of the experiments the surface of the 

 medium was visibly wet by the vapor arising from the breath. 



In this one case, the conditions of the experiment were as 

 follows : 



Three plates containing agar (Series XII) were all exposed 

 at a distance of about 7 centimeters and for two minutes before 

 a patient with marked dyspnoea and who died two hours after- 

 ward. A suspension of the bacterial growth upon one of these 

 plates, which covered almost the entire surface of the plate, 

 was made and a portion rubbed with the side of a scalpel over 

 the abdomen of a shaved guinea pig and the skin then freshly 

 scarified. The animal died of plague infection six and one-half 

 days later; there were inguinal buboes and miliary nodules in 

 the spleen. The animals inoculated with the colonies from the 

 other 2 plates exposed in exactly the same manner did not 

 develop plague infection. The results obtained from the exam- 

 ination of this one plate are different from those obtained from 

 the remaining 38 plates exposed before patients who did not 

 cough. Two possible explanations of the result suggest them- 

 selves, first, that the plague bacilli reached the medium on the 

 plate exposed before the patient in the plague ward in some 

 other way than by the expired air from the patient ; and, secondly, 

 that the plate was infected with plague bacilli by the droplet 

 method through the forced expirations of the patient during 

 the time this one plate was exposed. 



The remaining number of plates (35)^ were exposed before 

 patients who coughed during the time of exposure, and in 15 

 instances colonies of plague bacilli developed on the media in 

 the exposed plates. In some cases more than 100 colonies of 

 this organism were obtained upon the media after a single cough, 

 sometimes in almost pure culture. 



Guinea pigs, the abdomens of which had been shaved and 

 extensively scarified just before the time of the experiment, 

 were exposed before 3 cases of pneumonic plague for a period 

 of two minutes and at a distance of 5 centimeters from the 

 mouth, the abdomen being placed toward the mouth. The 

 breathing of the patients in all of these experiments was so 



^ In 4 other instances the patients talked during, the time of the exposure, 

 but no plague bacilli were demonstrated on these plates. 



