SPIRILLUM RUBRUM 453 



tents of the tube then becomes liquid, a tough pellicle 

 forming on the surface. It grows on carbolated media. 



Agar- Agar. — Grows rapidly over the whole surface ; in 

 the depth is seen the characteristic woolly appearance. 



Potatoes. — A white dry expansion is formed. 



Spirillum Rubrum. — This organism is found in water, 

 garden earth, etc. Forms spirilla with two or three twists 

 on solid media, but in broth will give rise to long threads 

 with up to fifty twists. It is about twice as thick as the 

 cholera spirillum. The shorter spirals are very motile. 

 Shining spots are seen in the body of the organism, which 

 are probably spores. Cultural characters : 



Gelatine Plates. — The colonies develop very slowly, often 

 requiring eight or ten days to make their appearance. 

 They form gray or pale-red centres, with granular contents 

 and a smooth rim. The depth-colonies become wine-red 

 in colour. No liquefaction of the gelatine takes place. 



Gelatine Tubes. — Grows in the depth as a wine-red streak, 

 but at the surface, where the air has access, no colouring- 

 matter is formed. 



Agar-Agar. — A moist, shining, gray expansion forms, 

 becoming red in the thicker part of the growth. 



Potatoes. — Very slowly small red colonies are formed, 

 which do not increase above the size of hemp-seed. 



Broth. — The broth becomes turbid, and a red sediment 

 is formed. 



Sarcina Alba. — This organism occurs in air, water, etc., 

 in the form of small cocci arranged in two, four, and eight 

 elements. Cultural characters : 



Gelatine Plates. — Grows slowly, giving rise to small 

 white colonies. The gelatine is slightly liquefied. 



Gelatine Tubes. — Produces a white expansion. 



