QUALITATIVE BACTERIOLOGICAL ANALYSIS. 69 



an irregular margin, and from the commencement of the rather 

 quick liquefaction they send out thread-like branches ; later a 

 violet colour is developed. In gelatine-stab there is liquefac- 

 tion in the form of a funnel and a violet-coloured deposit. There 

 is a growth in broth and a violet-coloured deposit. On agar 

 there is a deep blue growth. It reduces nitrates. It is a 

 small motile bacillus, often in pairs, and forms spores. 



B. Violaceus Lutetiensis. 



Isolated by Mace from water. This organism is probably 

 identical with the above. It is a short bacillus, which liquefies 

 gelatine very rapidly. 



B. Amethystinus (Eisenberg). 



Found by Jolles in well-water (B. membranaceus amethys- 

 tinus). In gelatine plates the surface colonies resemble typhoid 

 colonies ; at first they are colourless ; later, they acquire a dark 

 violet colour, and the gelatine is only liquefied in ten to fourteen 

 days. When liquefaction has taken place the colony floats as a 

 large violet pellicle on the liquefied gelatine. In gelatine-stab 

 it forms a yellowish white expansion on the surface, which in 

 ten to fourteen days assumes a violet colour and the gelatine is 

 slowly liquefied. After about four weeks a thick, dark violet 

 pellicle covers the surface of the liquefied gelatine. On agar it 

 forms a yellowish-white growth, which in about ten days assumes 

 a dark violet colour with a metallic lustre. On potato it forms 

 a dirty yellow or olive-green coloured growth. In broth it 

 forms a violet-coloured pellicle on the surface, and the broth 

 itself is coloured brown. It is a small non-motile bacillus, 

 which does not grow at 37 C. 



B. Amethystinus Mobilis. 



Described by Germano. Its colonies resemble the above by 

 forming violet-coloured membranes resting on slowly liquefied 

 gelatine. It is, however, a large motile bacillus, which produces 

 a brown growth on potato. 



B. Coeruleus (Smith). 

 Found by Smith in river water. It is a thin bacillus, often 



