K— BOTANY 205 



sugar, for a similar if not identical ' organism ' has been found in 

 Jamaica. 



Mexican Tibi also owes its production to the association of a yeast 

 {Pichia Radaisii) and a bacterium (Bacterium mexicanum), which occur 

 naturally on the prickly pear (Opuntia) in rounded transparent masses 

 similar to the ginger-beer plant. These placed in a syrupy solution 

 produce a sparkling, slightly acid drink very popular with the working 

 classes. 13 The yeast is unable to act in the presence of air ; the bacterium 

 plays the part of keeping down the amount of oxygen. The natural 

 occurrence of the ' organism ' recalls the fact that the sugary exudations 

 from trees, known as slime-flux, constantly harbour a mass of bacteria, 

 yeasts, and interesting yeast-like fungi, several of which are known only 

 from this habitat. 



Another combined yeast-bacterium mass which has been distributed 

 widely over northern Europe as a cure for such ailments as consumption 

 is grown in sweetened tea, and forms a heavy gelatinous scum on the surface. 

 G. Lindau, who obtained it from Curland, described it as a new genus 

 of yeasts, Mednsomyces (M. Gisevii). P. Lindner, however, showed 

 that it is a mixture of organisms, but mainly a yeast (Saccharomycodes 

 Ludwigii) and a bacterium (Bacterium xylinum). 



Recently what is essentially the same beverage has received considerable 

 notice in the eastern tropics as Tea Cider. Ordinary tea has ten per cent, 

 sugar added to it and is then inoculated with the ' mould ' Saccharo- 

 mycodes Ludwigii — Bacterium xylinum. The time for the completion of 

 the fermentation is from two days upwards depending upon the altitude 

 and temperature. The beverage contains up to three per cent, alcohol and 

 is slightly acid, with an agreeable aromatic flavour. There has been 

 a good deal of propaganda in Java which has led to its increased popu- 

 larity. Its reputed medicinal qualities have also brought about an extensive 

 use in Javan villages. The attempt to popularise it in Ceylon has not been 

 viewed with favour by the excise authorities. C. H. Gadd says that the 

 bacterium is the essential constituent, for this gives the characteristic 

 flavour and odour, and that yeasts other than Saccharomycodes Ludwigii 

 will work in conjunction with it. 



As indicating how such organisms may have first entered into use 

 I may mention that I have isolated a similar gelatinous mass from the 

 dregs accidentally left in a teacup for a month or so. 



The fermentation of milk is deliberately arranged in many parts of 

 the world with resultant beverages which go far back in the history of the 

 peoples ; milk-wine according to Herodotus was known to the Scythians. 

 One of these is Kephir, the effervescent, alcoholic sour milk of western 

 Asia. The kephir grains which are employed in the production of the 

 drink are white or yellowish irregularly shaped masses, about the size 

 of a walnut, tough and cartilaginous when fresh and brittle when dry. 

 The tradition is that they were a divine gift to Mohammed ; they are 

 regularly sold in druggists' shops. H. von Freudenreich isolated a yeast 



13 Pabst states that Tiby or ' grains vivantes ' was used in Paris about 1890 

 to ferment weak sugar solutions. The name suggests a further similarity to the 

 ginger-beer plant. 



