62 MICRO-ORGANISMS AND FERMENTATION. 



wort-gelatine wrinkled colonies develop at 25C. in the course 

 of 18 days, which are slightly raised and present a sharp 

 outline or one slightly jagged. In " double beer " the 

 temperature maximum of the growth is 42 C., minimum 

 5-6 C. 



This species is more frequently met with in high- than in 

 low-fermentation breweries. 



Bacterium Kuetzingianum (HANSEN) (Fig. 16) forms a 

 dry film, on " double beer " at 3 4 C. which raises itself high 



above the liquid, up the side of the 

 flask. Under the same circum- 

 stances as in the case of B. 

 Pasteurianum the slime is coloured 

 blue. The film consists of small 

 rod-bacteria, which are most fre- 

 FIG. K5. Bacterium Kuetzingianum. queiitly single or connected in 



(After HANSEN.) l ./ => 



pairs, but seldom form chains. 



The thread-form at 40-40 J C. presents almost the same 

 appearance as that of B. Pasteurianum. In plate-cultures 

 with wort-gelatine at 25 C. the colonies are analogous 

 to those of the previous species. They consist almost ex- 

 clusively of small, single rod-bacteria. In meat-water peptone- 

 gelatine the colonies likewise resemble those of the two previous 

 species. On sowing drops on wort-gelatine at 25C. colonies 

 develop in the course of 18 days resembling those of B. 

 Pasteurianum, but with a smooth surface, without wrinkles. 

 On "double beer" gelatine these colonies are slimy, whilst in the 

 two previous species they have a dry surface. 



In "double beer" the temperature maximum of the growth is 

 42 C., minimum 6-7 C. 



This species was found in "double beer." 



Bacterium xylinium is essentially different from these 

 three species. It was described by ADRIAN J. BROWN in 1888, 

 who examined it especially from a chemical point of view. 

 This species is used in England for making vinegar. It forms 

 a film, the slime of which becomes cartilaginous and tough like 

 leather, the growth gradually filling up the whole liquid. 

 This species is essentially different from the three first described 

 in another respect, viz. : the slimy envelope in this species 



