BACTERIA. 77 



Peters described another bacillus, which he found among 

 the organisms occurring in leaven, and which possesses a 

 peptonising power. Small rods grow out of the spores, and 

 these rods increase to long filaments, which in their turn 

 divide into rods. In ordinary nutritive gelatine this species 

 does not thrive well, if at all ; whilst, on the other hand, 

 it thrives readily and vigorously when " soluble starch " is 

 added ; the gelatine rapidly becomes liquefied. Spores appear 

 abundantly in cultures in neutralised yeast-water. In sus- 

 pended drop-cultures it was found that small pieces of boiled 

 white of egg were much acted on or completely dissolved by 

 this- species. 



7. SARCINA FORMS. 



In addition to the above-mentioned Pediococcus acidi 

 lactici there also occur in fermenting liquids a number of 



FIG. 15 : Sarcina. 



other spherical bacteria, the life-histories of which are only 

 very imperfectly known. Both in bottom-fermentation and 

 in top-fermentation (especially in distilleries and pressed- 

 yeast factories) different varieties of Micrococci occur, the 

 injurious action of which is strongly emphasised in the 

 journals relating to these industries. This has, however, only 

 been satisfactorily demonstrated by direct experiment in a 

 single case (see Section on " Slime-forming bacteria "). In 

 bottom-fermentation lager-beer these forms appear as small, 

 more or less spherical, water-grey bodies, sometimes isolated, 

 sometimes arranged in groups, generally in groups of four. 

 They were described by Hansen under the name of Sarcina 

 (Fig. 15). Organisms belonging to this group are found in 

 very different localities. The true places of growth of the 

 individual species are, however, not yet known. 



Reincke often observed such forms, both in bottom- and 



