1894.] Microscopical journal. 389 



ease and its bacteriological character. The bacilli, he says, are 

 to be found in the blood, in the buboes, in the spleen, and in 

 all other internal organs of the victims of the plague. The 

 bacilli are rods with rounded ends, which are readily stained 

 by the ordinary aniline dye, the poles being stained darker than 

 the middle part, especially in blood j^reparations, and present- 

 ing a capsule sometimes well marked, sometimes indistinct. 

 The bacilli found in the spleen are best stained by a solution 

 of methyl blue. The bacilli show very little movement, and 

 those grown in the incubator, in beef tea, make the medicine 

 somewhat cloudy. The growth of the bacilli is strongest on 

 blood serum at the normal temperature of the human body. 

 Under these conditions they develop luxuriantly, and are moist 

 in consistence and of a yellowish-gray color. They do not 

 liquefy the serum. On agar-agar jelly they also grow freely. 

 The different colonies are of a whitish-gray color, and by a re- 

 flected light have a bluish appearance; under the microscope 

 they appear moist and in rounded patches with uneven edges. 

 At first they appear everywhere as if piled up with " glass- 

 wool," and later as if having dense large centers. If a cover- 

 glass preparation is made from a cultivation on agar-agar, and 

 after having been stained is observed under the microscope, 

 long threads of bacilli are seen which might on careless inspec- 

 tion, be mistaken for a coccus chain, but are recognized with 

 certainty as threads of bacilli under closer observation. The 

 growth on agar-gelatin is similar to that on agar-agar. In a 

 puncture cultivation at the ordinary temperature after a few 

 days they are found growing as a fine dust in little points 

 alongside the puncture, but with very little growth on the sur- 

 face. 



Dr. Kitasato experimented on animals and found that mice, 

 rats, guinea-pigs and rabbits were susceptible to inoculation. 

 If they are inoculated with pure cultivations, or with the blood 

 of a patient in which the bacilli have been observed, or with 

 the contents of a bubo, or with pieces of the internal organs, or 

 even with the contents of the intestine, they become ill in from 

 one to two days, according to the size of the animal. Their 

 eyes become water}'^, they show disinclination for any effort ; 

 later thej^ avoid their food, and hide quietly in a corner of the 

 cage. The parts around the point of inoculation are infiltrated 



