ROPINESS IN INFUSIONS. 283 



absence of air. A thorough mycological 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 

 FE. KUTZING (I.), who ascertained that the lower orders of plants 

 here in question are partly algae and partly fungi, the schizomy- 

 cetes 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 hypo- 

 theses were formerly current. Thus, for instance, it was asserted 

 that the mucic acid in the leaves of digitalis exerts a coagulating 

 influence on the pectin bodies also present therein. W. BRATJ- 

 TIGAM (I.) found in a ropy infusion of this kind a fission fungus, 

 which he named Micrococcus gelatinogenus, endowed with the pro- 

 perty of gelatinising vegetable infusions (e.g. Ipecacuanha?, Radix 

 Althece, Senegce, Folia Farfarce, and especially Folia Digitalis), when 

 mixed with sugar-cane, lactic acid being produced 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 gum- 

 mosum, 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 wide- 

 spread 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 Feh ling's 



