QUALITATIVE BACTERIOLOGICAL ANALYSIS. 13? 



Potato-culture. Potato does not seem to be a favourable 

 medium for the development of this species. Repeated trials 

 at different temperatures have failed to induce a growth. 



Milk. There is no visible change in twenty days. The 

 reaction, however, is slightly acid. 



Broth. Becomes turbid very slowly. A scanty white pre- 

 cipitate is formed after some time. No skin. 



Nitrate-broth. There is no reduction to be observed in forty 

 days. 



Microscopical Characters. Fair-sized, plump bacilli, with 

 rounded ends. Generally occur singly or in pairs. No spore 

 formation observed. About 2' JJL long, 1 JJL broad ; motile. 

 Grow better at 37 C. than at 21 C., and develop feebly under 

 a mica plate. 



Bacillus Rubescens. 



Isolated from Lawrence sewage. 



Plate-cultures. A slow growth. The young colonies beneath 

 the gelatine are usually round, sometimes oval. On coming to 

 the surface they rise into a projecting porcelain- white drop. 

 The colonies increase in size slowly, and eventually take on a 

 slight brownish tint. 



Gelatine-tubes. The growth is slow and mainly on the surface, 

 where a porcelain- white, nail-head projection is found. There 

 is only a slight growth along the line of inoculation. There 

 is good growth in slightly acid gelatine. 



Agar-tubes. There is a rapid surface growth, white and 

 lustrous. At first the growth is smooth, but later becomes 

 crinkly, and the whole skin is much wrinkled. In cultures 

 about three weeks old a slight pinkish tinge can be seen. 



Potato-cultures. There is a rapid luxuriant growth on potato. 

 At first the colour of the growth is light brown, but this slowly 

 changes to pink. In three weeks there is a luxuriant, projecting 

 growth, tinted a delicate flesh-pink. The potato itself is not 

 coloured. 



Milk. The milk is not coagulated, and gives a good alkaline 

 reaction. In long-standing cultures a slight pinkish tinge is 

 observed at the surface of the milk. 



