BACTERIA. 91 



cises diastatic action and frequently occurs in the outer husk 

 of maize. PETERS found a bacillus in leaven which brought 

 about the solution of starch. In ordinary gelatine-plate 

 cultures this fungus forms peculiar curved colonies, consisting 

 of long filaments about 0*5 //. thick. In beer- wort the bacillus 

 forms rods which exhibit very active movement, and gradually 

 produce a film on the surface. The spores are rod-like. 



Bacteria have also been found which cause the solution of 

 albuminoid substances, for example, Microccocus prodigiosus. 

 The peptonising species which are active during the ripening of 

 cheese should be included in this class. 



8. SARCINA FORMS. 



In addition to Pediococcus acidi lactici, described above, 

 there occurs in fermenting liquids a number of spherical bacteria, 

 the life-histories of which are but imperfectly known. Both 

 in bottom- and top-fermentation (especially in distilleries and 

 pressed-yeast factories) different varieties of Micrococci occur, 

 the injurious action of which is strongly emphasised in the 

 technical journals. 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, clear grey bodies, sometimes isolated, <S> ^ 

 sometimes arranged in groups, generally in Q o, <?g 



groups of four. They were described by 



J J FIG. 24. Sarcina. 



HANSEN under the name of Sarcina (Fig. 24). 

 Organisms belonging to this group are found in very different 

 localities. The sources from which the individual species are 

 derived are, however, not yet known. 



EEINCKE found that lager-beer infected with such bacteria 

 soon yields a considerable sediment, and develops a bad odour 

 and taste. Berlin white beer often assumes a red colour ; it 

 is then found to be infected with many Sarcina forms, the 

 growth of which increases considerably after a few days at 

 a somewhat higher temperature; temperatures between 10 

 and 1 4 C. are stated by REINCKE to be particularly favourable. 

 However, he rightly emphasises the fact that it is not certain 



