148 MICRO-ORGANISMS AND FERMENTATION. 



to produce ropiness in English beer. This species occurs as 

 diplococci and tetrads, and gives yellow wax-like colonies 

 on meat- juice gelatine. The disease made its appearance in 

 the beer after a lapse of six to eight weeks, but it was not 

 usually possible to produce it by inoculation with pure cultures 

 of the species in sterile beer. Close to the fermentation room 

 there was a pork-butcher's premises, in which putrefying 

 matter had accumulated ; after this had been removed and 

 the soil dug and cleaned, the disease disappeared. 



Fellowes also examined several English beers affected by 

 this disease, and prepared pure cultures of the bacteria present, 

 but by inoculation of the cultures in beer he did not succeed 

 in preparing a beer containing these organisms and showing 

 a viscosity corresponding to that of the sample from which 

 they came. 



Heron undertook a thorough study of a slime-ferment 

 which occurred in English beers, a very small coccus, which 

 gradually elongates, and by contracting in the middle assumes 

 the form of a dumb-bell. The two ends may also expand in 

 a direction at right angles to the first growth, and assume a 

 similar shape. At a later stage the species takes on the form 

 of rosaries (zooglcea). The beer attacked loses its acid simul- 

 taneously with the formation of mucilage, and acquires an 

 unpleasant taste. This species can only produce slime in 

 presence of yeast. Beer may be protected against its action 

 by increasing its acidity and adding more hops. The species 

 originates in malt dust, according to Heron. 



The so-called frog-spawn fungus Leuconostoc (Streptococcus) 

 mesenterioides was investigated by Cienkowski and van Tieghem 

 and subsequently by Zopf and Liesenberg (Fig. 27). Both the 

 European form and the variety found by Winter in Java occur 

 spontaneously in beet-juice and in the molasses of the sugar 

 factory, and in molasses distilleries, in which they form large 

 slimy masses (" frog-spawn ") and multiply vigorously. The 

 fungus forms chains of cocci, alternate pairs of which are 

 always more closely united. In contrast to the observations 

 of earlier workers, who thought that certain of these cocci 

 enclosed spores, Zopf found that they present no differences 

 morphologically or physiologically ; spore-formation could in 



