SPIRILLA IN WATER 153 



not liquefied, the colonies having a tendency to spread out 

 over the medium in a thin superficial film. They show a 

 dull white colour and an irregularly indented border. In 

 thrust-cultures white buttons develop along the needle- 

 track and a delicate film on the surface. The colonies 

 on potato are yellow and juicy, and a white layer appears 

 on serum. The micro-organism is also capable of growth 

 in the absence of oxygen upon nutrient media containing 

 grape-sugar, and then generates a gas consisting of hydrogen 

 and carbon dioxide. Eabbits succumb to a subcutaneous 

 injection in from one to three days, with the symptoms of 

 diarrhoea and collapse. 



According to Gasser, an agar medium tinted with 

 fuchsine is decolorised only by this bacterium and the bacillus 

 of typhoid fever, whilst a sufficient point of distinction 

 between these two is, that the growth of Bacterium coli 



■ PlageUa 

 Fig. 57. — SrmiLLrji ukduia, with Flagella. Magnified 800 times. (After Lbffler.) 



commune remains restricted to the strip inoculated, where- 

 as that of the typhoid bacillus forms a tolerably broad 

 streak with very bowed and irregular edges. 



Spirilla in water. — Spirilla are found in copious numbers 

 in stagnant water, and are marked by an exceedingly active 

 motility, darting across the field with manifold twists and 

 turns. They often lie together in clumps, which look to 

 the naked eye like flakes of mucus. The individual spirilla 

 possess from one and a half to four turns, or sometimes as 

 many as six, and have some flagella on their ends. They 

 are described as Spirillum undula (fig. 57). 



