622 THE GUM FERMENTATION OF SUGAR CANE JUICE, 



vulgatus. The colour is partly whitish-grey, partly yellowish or 

 yellow or even reddish-brown. The culture finally covers the 

 potato as a slimy mass. 



Bacillus mesentericus (fuscus) differs from vulgatus chiefly in 

 colour and in not liquefying gelatine so quickl3^ The liquefied 

 gelatine in stab culture has a surface film. The stroke on agar 

 is yellow-brown. On potato the growth is raised, moist glisten- 

 ing, greyish-yellow and slimy, afterwards becoming a dull raised 

 network. Traces of indol are formed in bouillon. 



Bacillus liodermos differs from vulgatus in forming on potato a 

 smooth glistening yellowish- white syrupy growth which is soluble 

 in water and precipitated from solution by alcohol. 



Bacilhts mesentericus ruber is very similar to vulgatus. It 

 forms colonies of various shape on gelatine which is slowly 

 liquefied. The agar-stroke is translucent, grey-white, moist 

 glistening, and eventually becomes like a network. The growth 

 on potato is mesenter3^-like and of a rose-red colour which ulti- 

 mately becomes reddish-brown. 



It is quite probable that the four members of the potato group 

 are all varieties of one typical bacterium, which we may assume 

 to be that most commonly occurring, viz., vulgatus. The others 

 differ but slightly from it. Examples of a similar variation are 

 not wanting among the bacteria. Among the yeasts the varieties 

 of Sacch. cerevisice appear to be limited only by the number of 

 breweries. Conn noted the occurrence in nature of a white 

 coccus, varieties of which did or did not liquefy gelatine. 

 Schierbeck* separated from one sample of milk races of lactic 

 bacteria which differed in their fermentative power, and moreover 

 the difference was apparently fixed so far as the race was con- 

 cerned. 



But coming to the vulgatus group itself, there are instances 

 where one or other of the members have developed the power of 

 causing bread to become slimy. Uffelmannf ascribed the 



Schierbeck, Cent. f. Bakt. Ite Abt., vii. 239, Eef. 

 t Uffelmann, Cent. f. Bakt. Ite Abt., viii.. 481. 



