TRANSMISSION OF THE INFECTION. 153 



and 5 = a bacillus with very delicate colonies which partially decolorizes 

 by Gram's stain; these two cultures were later inoculated into guinea 

 pig No. 5305, 1 a-se of each culture being rubbed in different places over the 

 shaved and scarified abdomen; the animal remained healthy. 35 A 2, 3, 

 and 4 are cultures of a small bacillus which does not decolorize by Gram's 

 stain; this culture was inoculated into guinea pig No. 5319, which remained 

 healthy. 35AG=ia bacillus which partially decolorizes by Gram's stain; 

 this organism was later inoculated into guinea pig No. 5321, which remained 

 healthy. 



Plate B exposed at a distance of about 7 centimeters for two minutes. 

 Patient breathing heavily; no cough during time of exposure. Result 

 after forty-eight hours: Irregular surface growth, covering practically 

 the whole surface of the agar in which many isolated, round colonies, from 

 2 to 4 millimeters in diameter, are situated. The growth on the plate was 

 suspended in a few drops of peptone solution, and several cese?i rubbed 

 over the shaved and scarified abdomen of guinea pig No. 28 with a scalpel; 

 the animal died six and one-half days after of typical plague infection ; 

 there was a haemorrhagic local lesion about the point of inoculation; 

 hsemorrhagic inguinal buboes; and the spleen showed early miliary absces- 

 ses; there was no pneumonia; smears from the spleen and bubo showed 

 innumerable plag-ue bacilli, and a culture of Bacillus pestis was obtained 

 from the heart. 



Plate C was exposed for two minutes at a distance of about 7 centi- 

 meters; no coughing during time of exposure. Result after forty-eight 

 hours: Irregular surface growth covering almost entire surface of the 

 plate, in which are scattered numerous colonies, 2 to 3 millimeters in 

 diameter. Just outside the edge are 3 small white colonies, which are 

 planted on agar slants. The growth on the surface of the plate was then 

 suspended in a few drops of saline solution and 3 oesen inoculated subcu- 

 taneously into mouse No. 26, which did not develop plague infection. 

 Results of the cultures on agar slants are as follows: 35Cl = a bacillus 

 which decolorizes by Gram's stain; the growth is rather heavy for plague; 

 the culture was inoculated later into guinea pig No. 5478, which remained 

 healthy. 35 C 2 and 3 ai*e cultures of a large bacillus which partially 

 decolorizes by Gram's stain; these 2 cultures were inoculated later into 

 guinea pigs Nos. 5316 and 5315, which did not develop plague infection and 

 remained healthy. 



Case 36. — Advanced case of pneumonic plag-ue. Plate exposed at a 

 distance of about 85 centimeters for one and three-quarters minutes. 

 Patient coughed five times during exposure. Only 3 colonies developed on 

 the plate. These were transplanted to agar. Two of these colonies failed 

 to develop ; the third proved to be a coccus or very short bacillus which 

 partially decolorized by Gram's stain. 'CJiis organism was later inoculated 

 into guinea pig No. 5314 by the cutaneous method. The animal remained 

 healthy. 



From these experiments it may be seen that of the 82 plates 

 containing agar, 8 were exposed in the wards in the neighbor- 

 hood of pneumonic-plague patients, 4 were exposed before pa- 

 tients who talked during the time of the exposure, and 35 before 

 patients who coughed during the time of the exposure. In 39 

 instances the plates were exposed before patients who did not 



