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. u. Parasitenk., Sept. 6, 1897, Bd. xxii., Nos. 6 and 7, p. 170. 2 Brit, Med. Joztr., June 12, 1897, p. 1461.