THE BIOLOGY OF MICROBES, ETC. 171 



end. They swarm when causing decomposition in 

 vegetable infusions. According to Prazmowski, 

 Vibrio rugula develops a spore at one end of the 

 cell. 



SPIRILLA. 



Spirillum tyrogenum. This spirillum measures 

 about 0*8 to 1*5 p, in length. On gelatine plates 

 (see Fig. 24) it forms colonies of a greenish-brown 

 colour. In test-tubes the gelatine becomes liquid 

 along the needle-track, while on agar-agar a pale 

 yellow layer develops. This microbe, which is 

 non-pathogenic, was isolated, by Deneke, from old 

 cheese. S. tyrogenum is capable of withstanding a 

 temperature of 18 C. for several days. 1 



Spirillum Finkleri. The rods are curved, and 

 they are larger and thicker than the Spirillum 

 cholera Asiaticce. On gelatine-plates they grow 

 rapidly, forming small white dots with a brownish 

 tinge; and the gelatine is liquefied very rapidly. 

 The fluid (from the liquefaction) becomes completely 

 turbid, whereas in S. cholerce Asiaticce the upper 

 part remains clear. In gelatine tube cultivations, 

 liquefaction occurs in the form of a funnel-shaped 

 tube, and the fluid becomes turbid. On agar-agar 

 and potatoes white films or layers are formed. S. 

 Finkleri was discovered in the dejecta of cases of 

 cholera nostras, and it was said to be identical with 

 the Spirillum of Asiatic cholera; but it is quite 

 distinct. 



1 Griffiths in Proc. Roy. Soc., Edinb., vol. xvii. p. 263 ; and 

 Researches on Micro-Organisms, p. 176. 



