SARCINA. 157 



a lager cask the growth remained at the bottom, and th& 

 bacteria did not exert any appreciable influence on the liquid r 

 whereas in the case of a vigorous secondary fermentation 

 they were carried upwards in the liquid, along with the carbon 

 dioxide bubbles, after which the disease manifested itself. 

 Rousing the beer might, therefore, be injurious in such cases, 

 An addition of hops to lager beer exerts a retarding influence on 

 these bacteria, as on the majority of bacteria occurring in beer. 

 vSchonfeld inoculated cultures (from diseased beer cultivated 

 on yeast- water gelatine) into pasteurised beer, and produced, not 

 only a turbidity, but also an acid sweet, disagreeable flavour. 

 Two species have been described by N. H. Claussen, which 

 were isolated after he had checked the growth of other organ- 

 isms occurring in beer by a slight addition of acid ammonium 

 fluoride. The beer-cultures were allowed to develop in hopped 

 wort and in pasteurised beer, and when inoculated in beer 

 brought about the characteristic disease phenomena. Both 

 species grow in the usual nutritive liquids either neutral or 

 slightly acid, whereas a minute quantity of free alkali restricts 

 their growth. The most favourable temperature for their 

 growth is 23-24 C. Neither liquefies gelatine. They 

 grow in wort both when oxygen is fully excluded, and 

 also in presence of the full quantity in the atmosphere. The- 

 one, P. damnosus, usually imparts an unpleasant odour and 

 flavour to beer, but only forms a slight deposit in the liquid ; 

 the other, P. perniciosus, causes, in addition to the deterioration 

 of flavour and odour, a turbidity in the liquid. Schonfeld has 

 isolated species from diseased beers with the help of sweet 

 wort gelatine, and especially on dry-yeast gelatine. He found 

 that species that are dangerous for lager beer, imparting the 

 Sarcina odour and objectionable flavour, as well as turbidity, 

 only produce a comparatively minute quantity of acid in sweet 

 wort, and give a peculiar odour slightly resembling honey : 

 for this reason he gave the group the common name of P. 

 odoris mellisimilis (he assumes that this group is identical with 

 Claussen's P. perniciosus). In contrast with this a group of 

 species exists which occur in lager beer and " Weissbier " 

 producing large quantities of acid in sweet wort, and, 

 according to Schonfeld's observations, much turbidity, but not 



