BUBONIC PLAGUE. 435 



1. Plague with buboes. 



2. Plague without buboes, but with a primary specific 

 pneumonia in which the bacilli occur in immense num- 

 bers in the affected pulmonary tissue, but sparingly in the 

 blood and kidney. 



The studies of Kitasato and Yersin show that in blood 

 drawn from the finger-tips and in the softened contents 

 of the glands a small bacillus is demonstrable. The 

 organisms are small, stain much more distinctly at the 

 ends than in the middle, so that they resemble diplo- 

 cocci, and in fresh specimens seem to be surrounded by 

 a capsule. Kitasato compares the organism to the well- 

 known bacillus of ckicken-cholera. It is feebly motile 

 (according to Abel, entirely non-motile), and does not 

 seem to form spores. Nothing is said in the original 

 descriptions about the presence of flagella, though it is 

 probable from the studies of Gordon l that some, at least, 

 of the bacilli may be possessed of them. It does not 

 stain by Gram's method. 



When cultures are made from the softened contents of 

 the buboes the bacillus may be obtained almost or quite 

 pure, and is found to develop upon artificial culture- 

 media. In bouillon a diffuse cloudiness results from 

 the growth, as observed by Kitasato, though in Yersin's 

 observations the culture more nearly resembled erysipe- 

 las cocci, and contained zooglea attached to the sides and 

 at the bottom of the tube of nearly clear fluid. 



According to Haffkine, 2 when an inoculated bouillon 

 culture is allowed to stand, perfectly at rest, on a solid 

 shelf or table a characteristic appearance results. In 

 from twenty-four to forty-eight hours, the liquid remain- 

 ing limpid, flakes appear underneath the surface, forming 

 little islands of growth, which in the next twenty-four 

 to forty-eight hours grow down into a long stalactite-like 

 jungle, the liquid always remaining clear. In four to 



1 Centralbl. f. Bakt. n. Parasitenk., Sept. 6, 1897, Bd. xxii., Nos. 6 and 7, 

 p. 170. 



2 Brit. Med. Jour., June 12, 1897, p. 1461. 



