ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 285 



opalescent for a yellowish coloiir passing readily into green, with a 

 dark violet pellicle. The colour could not be due to the accidental 

 presence of aniline-pigment. A closer examination showed also that 

 the colouring-matter of the pellicle was not readily soluble in water, 

 and hence could not be due to Chromococcus violaeeus ; and that it was 

 composed of innumerable rod-bacteria which appeared motionless 

 when collected into masses, but distinctly displayed motion when 

 swimming about freely in the fluid. These violet bacteria bore a great 

 resemblance in their form and dimensions to Bacterium Termo ; they 

 were cylindrical, about • 6-1 • /x thick, and 2-3 ^ long, being from 

 two to three times as long as broad. When observed singly, the 

 colour appeared scarcely blue, while when massed together the violet 

 tint was very perceptible. The pigment was insoluble in water, slowly 

 soluble in ether, very rapidly in alcohol. Addition of water to the 

 alcoholic solution produced no precipitate, leaving the fluid clear. 



The author was able in most cases to infect fresh prepared solution 

 of white of egg with bacteria from the pellicle. At a temperature of 

 1 7^-1 9° C. the first traces were visible after about eight days, a few 

 violet dots making their appearance on the surface of the fluid. The 

 following is the diagnosis of the new species. 



Chromobacterium violaceum. The cylindrical cells are isolated, 

 two to three times as long as broad, are possessed of an oscillatory 

 motion, and are coloured violet by a pigment insoluble in water. The 

 thickness varies from • 6 to 1 /a, the length between 2 and 3 fu They 

 vegetate on a solution of white of egg. 



Cultivation of the Bacterium of Foot-Rot.* — The course of this 

 disease is stated by M. Toussaint to occupy at least thirty-five days, 

 but it may be recognized in sheep affected with it during the 

 incubation-period, which may last more than twenty days. The 

 lymph taken from pustules formed by inoculation may be utilized 

 to form a growth of the parasite ; this growth can be propagated 

 in broth of different kinds of meat — best in that of rabbit or 

 mutton broth — and even in yeast-solution. In this case the gi'owth 

 develops strongly in from two to three days, filling the liquid with 

 bacteria and spores, and forming pellicles on the surface ; in from 

 four to five days the liquid becomes clear, as the bacteria then sink to 

 the bottom in the form of spores. In the first stage the bacteria 

 commence at a length of * 003 to • 004 mm. and are then very 

 active ; they elongate and become segmented ; usually but two joints 

 are found in union, of which one is generally larger than the other ; 

 at the third or fourth day the longer joint produces a spore at each 

 end, and sometimes one in the middle ; the small joint forms one 

 spore which, having a greater diameter (viz. • 001 mm.) than that of 

 the joint, gives it a club-shaped outline. The spores are oval, and refract 

 the light, and are smaller than those of anthrax. Inoculation of 

 sheep from these liquids produces pustules which reach their greatest 

 size in from fifteen to eighteen days ; they never suppurate, but dis- 

 appear without any general accompanying eruption, and they leave no 



* Comptes Eendus, xcii. (1881) pp. 362-4. 

 Scr. 2.- Vol. I. X 



