THE GINGER-BEER PI/ANT. 1 63 



When seen in the fresh state, as it comes from flasks or other vessels, the ginger-beer plant pre- 

 sents the appearance of solid, white, semi -translucent, irregular, lumpy masses, not unlike pieces of 

 soaked sago or tapioca; these lumps are brittle, like firm jelly, and their size varies from that of a 

 pin's head, or smaller, to that of a large plum, or larger. Opacity and brittleness vary, even in the 

 same lump. Fresh-dried lumps do not dissolve in water, even if boiled. When thoroughly dry they 

 are often hard and horny. Fresh moist specimens are usually distinctly acid, though in varying 

 degrees. The most striking characteristics of these lumps of ginger-beer plant become evident only 

 when they are placed in saccharine solutions. After some days in a closed soda-water bottle three- 

 fourths full of Pasteur's fluid, a lump of ginger, and a few lumps of the ginger-beer plant, kept in a 

 warm place, the liquid is found to be very turbid and more or less viscous. The fermentation goes 

 on rapidly. Much gas is produced and the container may explode if tightly closed. In time the 

 viscosity increases, and it sometimes happens that the liquid becomes so thick that the gas-bubbles 

 rise slowly. Viscosity is not due to the mere presence of yeast-cells, because they fall to the bottom, 

 but to the presence of innumerable swollen or slimy vermiform bodies distributed through the mass 

 of the liquor. Myriads of rod-shaped bodies (bacteria) are also observable. The increasing deposit 

 below is also found, in later stages, to consist of bacteria, swarming amongst the yeast-cells. The 

 "ginger-beer" is distinctly acid, as well as viscous. 



As time goes on, the surface of the liquid usually becomes covered with a dense scum, unless 

 very well corked and protected. 



The problems then which present themselves are : 



What is the yeast which so rapidly spreads in the earlier stages of fermentation? 



What are the slimy vermiform bodies in the liquor? 



What species of Schizomycetes are present? 



What does the scum consist of?, and finally, 



What have all, or any, of these organisms to do with the ginger-beer plant, and the con- 

 version of the saccharine liquor into "ginger-beer"? 

 In an effort to solve these problems, almost two thousand separate cultures, each extending 

 over periods of from several days to months, and even in some cases to two years, were made. These 

 cultures were of three kinds: (i) I^arge cultures in flasks, usually liquids, sometimes solid gelatin; 

 (2) smaller cultures in tubes; and (3) cultures in hanging drops, made in sterilized cells under the 

 microscope. Every piece of apparatus was heated in a hot-air chamber to at least 140° C. for 2 hours, 

 and everything was lifted by forceps, similarly treated. 



Various Organisms Found in the Ginger-Beer Plant. 



It was apparent from the start that the ginger-beer plant is a body, consisting of several organ- 

 isms, or, at least yielding more than one definite organism. Investigation has shown, however, that 

 two specific cryptogams constitute the ginger-beer plant proper, and are necessary for its formation 

 and peculiar action, while the rest are merely accessory or foreign organisms. 



Of the two essential forms, one is a new species of Saccharomyces, the other a new and very re- 

 markable species of schizomycete. 



Of two non essential forms, found in all the specimens examined, one is a yeast-like form, 

 Mycoderma cerevisiae Desm., while the other is the vinegar organism — Bacterium aceti Kiitz. 



The intruders most commonly met with are species of Saccharomyces, Bacillus, Micrococcus, 

 Oidium, Torula, Dematium, and one or two ordinary mould fungi, of which Penicillium is by far the 

 commonest. 



The new yeast Saccharomyces pyriformis which resembles S. ellipsoideus, is the most important 

 one met with in this investigation, being constant in every specimen examined, and undoubtedly 

 the yeast principally concerned in fermentation of ginger-beer. It induces active fermentation 

 in sugar-solutions, either cane-sugar, or glucose [no statement respecting lactose in this place, but 

 elsewhere it is said that milk sugar can not take the place of cane sugar or glucose], resulting in a 

 copious evolution of carbon dioxide gas, and in the formation at the bottom of the flasks, tubes, etc., 

 of a voluminous white pasty deposit, consisting of characteristic colonies of budding-yeast cells. 

 Pure cultures were readily obtained, both by the dilution method, and by growth on gelatin media; 

 cultures were obtained from single cells grown in hanging drops. The single cell is globoid, or more 

 commonly ellipsoid, or ovoid in shape, colorless and translucent, and measures from 6 to 7 m long X 

 5. 5m broad, though smaller and larger cells are found. The pyriform cells occur in the surface film. 

 There is no hmit to the size and shape of the colonies. 



In very active, vigorous cultures of this yeast, the protoplasm gives a strikingly clear glycogen 

 reaction — on adding iodine dissolved in an aqueous solution of potassic iodide, the cells turn dark 

 sienna red, or red-brown. Ascospores occur repeatedly, and with singular distinctness. They are 

 formed on moist gypsum blocks and also on the surface of gelatin. 



This species is named Saccharomyces pyriformis from characteristic pear-shaped aerobian cells. 



