336 APPLIED BACTERIOLOGY 



diameter, occur as diplococci and in short streptococci. 

 In old cultures they lose their motility, but on inoculating 

 into a saccharine liquid they regain their power of move- 

 ment. It will grow at 37° C. Cultural characters : 



Gelatine Tubes. — A pinkish-red expansion is formed. 

 The gelatine is very slowly liquefied. 



Agar-Agar. — A pinkish-red expansion is produced. 



Potatoes.- — A pinkish-red growth is produced. 



Bacillus Aquatilis. — Is found in water. It forms short 

 straight bacilli, three times as long as they are broad, 

 they occurring singly and in chains. This organism is 

 anaerobic, and will not grow above about 24° C. It reduces 

 nitrates to nitrites. Does not stain by Gram's method of 

 staining. Cultural characters : 



Gelatine Plates. — Forms mother-of-pearl-like dots, both 

 on the surface and in the depth. By age the colonies 

 become more raised, but do not grow in width. The 

 gelatine is not liquefied. 



Agar-Agar. — A moist white expansion is formed, which 

 only grows at room-temperature. 



Potatoes. — A gray-white irregular expansion forms, after- 

 wards becoming of a coffee-yellow colour. 



Bacillus Arborescens. — This organism was found by 

 Frankland in river-water. It forms slender bacilli about 

 2-5 /A long by 0'5 fi broad, and occurs in twos and threes, 

 also in long chains. Cultural characters : 



Gelatine Plates. — Branching wheatsheaf-like colonies are 

 produced, having a beautiful iridescent appearance. The 

 gelatine is slowly liquefied. 



Gelatine Tubes. — The medium is slowly liquefied, pro- 

 ducing a yellow deposit. 



Agar- Agar. — A dirty orange-coloured growth is slowly 

 produced. 



Potatoes. — A deep orange growth is produced. 



