218 ROPINESS IN MILK, WINE, BEER, ETC. 



study of this malady has, however, still to be made. Neither the Bacillus 

 viscosus sacchari, mentioned in chapter xxviii., nor other similar cause of 

 mucinous fermentation, is capable of giving rise to ropiness in wine, since none 

 of them is able to develop in acid media. 



One point is perfectly clear, viz., that the presence of sugar is a sine qua non 

 for the occurrence of the malady, since it forms the material from which the 

 mucus is produced. According to Nessler (an expert in the treatment of wines), 

 wines containing over 10 per cent, of alcohol are proof against ropiness. 



With regard to the ropiness of cider the most frequent malady to which 

 this beverage is subject nothing reliable can at present be reported. 



165. Ropiness in Infusions. 



This was microscopically investigated as far back as 1834 by FR. KtTziNG 

 (I.), who ascertained that the lower orders of plants here in question are partly 

 algae and partly fungi, the schizomycetes being the most frequently found 

 members of the latter group. A few examples are given below. 



It is well known that Infusum foliorum Digitalis very often becomes ropy, to 

 account for the occurrence of which divers hypotheses were formerly current. 

 Thus, for instance, it was asserted that the mucic acid in the leaves of digi- 

 talis exerts a coagulating influence on the pectin bodies also present therein. 

 W. BRAUTIGAM (I.) found in a ropy infusion of this kind a fission fungus, which 

 he named Micrococcus gelatinogenus, endowed with the property of gelatinising 

 vegetable infusions (e.g. Ipecacuanhas, Radix Althece, Senegce, Folia Farfane, and 

 especially Folia Digitalis), when mixed with sugar-cane, lactic acid being pro- 

 duced at the same time. The mucus is precipitable by alcohol. In nutrient 

 media devoid of sugar the micrococcus develops, but does not form mucus. 



Of interest to the analytical chemist is the Bacterium yummosum, also 

 obtained by E. RITSERT (II.) from a ropy infusion of Digitalis. This organism 

 turns the nutrient medium ropy only when saccharose (but not dextrose or 

 lactose) is present, and can therefore be employed as a reagent for cane-sugar 

 to detect the latter in presence of large quantities of hexoses, e.g. in wine-must. 

 It will develop in highly concentrated solutions of this sugar, its growth not 

 being impeded until the concentration exceeds 60 per cent. The mucus produced 

 by this fission fungus has received the name of gummose, a term likely to lead 

 to error, since a somewhat widespread malady attacking the vine, the sugar- 

 beet, and other plants, has long borne the name of gummosis or gummose. This 

 mucus is distinguishable from dextran chiefly by being optically inactive. In 

 addition to mucus the organism produces an uninvestigated acid, and a compound 

 of unknown constitution, which deviates the plane of polarised light to the right 

 and reduces Fehling's solution. According to the conditions of cultivation, Bac- 

 terium gummosum appears as long or short rods, diplococcus or streptococcus, 

 the first forms being motile and producing endospores. The addition of acetate 

 of potash or soda or of yeast ash to the nutrient solution (e.g. sugar-beet juice, 

 &c.) is highly favourable to development and to the production of mucus. 



The Bacillus gummosus, isolated by C. HAPP (I.) from a ropy infusion of 

 Digitalis, is characterised by its large size, the length being 5.0-7.5 /i, and the 

 breadth 0.6-2.0 /*. It exhibits an undulatory motion and forms endospores. In 

 cultures on slices of potato and beet the cells are globular, with a diameter of 

 0.7-0.8 (i, but when transferred to gelatin or agar-agar they quickly become 

 rod-shaped. Happ obtained from ropy Senega infusion a pure culture of 

 Micrococcus gummosus, the diameter of which is about 0.4 /t. A notable diffe- 

 rence exists between these two species with respect to their behaviour towards 

 sugars, the first-named being able to set up ropy fermentation only in presence 



