190 



NA TURE 



[December 24, 1891 



a considerable amount of blue rays. M. Teisserenc de Bort 

 explained the existence of a vertical barometric gradient, first 

 noticed in mountain observations, but lately measured more 

 exactly on the Eiffel Tower. — The zodiacal light as related to 

 terrestrial temperature observations, by O. T. Sherman. — 

 Features of Hawaiian climate, by C. L. Lyons, in charge of the 

 Weather Service there. The temperature averages for January 

 are 69° to 71°, and in July and August 78° and 79°. The daily 

 range is greater than is generally supposed, averaging 11° for the 

 year, and some days over 20°. The maximum temperature is 

 89°, and the minimum 55°. — High-level meteorological observa- 

 tories in France, by A. L. Rotch ; and other articles of minor 

 importance. 



SOCIETIES AND ACADEMIES. 

 London. 



Royal Society, December 17. — "The ' Ginger-beer Plant, 

 and the Organisms composing it : a Contribution to the Study 

 of Fermentation-yeasts and Bacteria." By H. Marshall Ward, 

 ScD., F.R.S., F.L.S., Professor of Botany at the Forest 

 School, Royal Indian Engineering College, Cooper's Hill. 



The author has been engaged for some time in the investiga- 

 tion of a remarkable compound organism known to villagers as 

 the "ginger-beer plant." 



It occurs as jelly-like, semi-transparent, yellowish-white 

 masses, aggregated into brain-like clumps, or forming deposits 

 at the bottom of the fermentations, and presents resemblances 

 to the so-called Kephir grains of the Caucasus, with which, 

 however, it is by no means identical. 



He finds that it consists essentially of a symbiotic association 

 of a specific Saccharomycete and a Schizomycete, but, as met 

 with naturally, invariably has other species of yeasts, bacteria, 

 and mould-fungi casually associated with these. 



He has successfully undertaken the separation of the various 

 forms, and groups them as follows : -- 



(i) The essential organisms are a yeast, which turns out to be 

 a new species allied to Saccharomyces ellipsoidetis (Reess and 

 Hansen), and which he proposes to call S. pyriformis ; and a 

 bacterium, also new anfl of a new type, and named by him 

 Bacterium verinifortne. 



(2) Two other forms were met with in all the specimens 

 (from various parts of the country and from America) examined 

 — Mycoderma cerevisicB (Desm. ) and Bacterhim aceti (Kiitzing and 

 Zopt). 



(3) As foreign intruders, more or less commonly occurring in 

 the various specimens examined, were the following : — 



o. A pink or rosy yeast-like form — Cryptococctis glutinis 

 (Fresenius) ? 



/3. A small white aerobian top-yeast, with peculiar characters, 

 and not identified with any known form. 



7. The ordinary beer-yeast — Saccharomyces cerevisicB (Meyen 

 and Hansen). 



S. Three, or probably four, unknown yeasts of rare occur- 

 rence. 



€. A bacillus which forms spores, and liquefies gelatine with 

 a greenish tinge. 



^. A large spore-forming bacillus, which also liquefies gela- 

 tine. 



1) and fl. Two — perhaps three — other Schizomycetes not 

 identified. 



I. A large yeast-like form which grows into a mycelium, and 

 turns out to be O'idium lactis (Fresenius). 



K. A common blue mould — Petiicillium glaucum (Link). 



X. A brown " Torula "-like form, which turns out to be 

 Dematium pullulans (De Bary). 



it.. One, or perhaps several, species of " Torula" of unknown 

 origin and fates. 



Saccharomyces pyriformis (n. sp.) is a remarkably anaerobian 

 bottom-yeast, forming spores, and developing large quantities of 

 carbon dioxide, but forming little alcohol. It has also an aero- 

 bian form — veil form of Hansen — in which the rounded cells 

 grow out into club-shaped or pyriform cells, whence the proposed 

 specific name. It inverts cane sugar, and ferments the products ; 

 but it is unable to ferment milk sugar. It forms rounded, 

 morula-like, white colonies in gelatine, and the author has 

 separated pure cultures from these. He has also studied the 

 development and germination of the spores, which are formed 

 in 24 to 48 hours at suitable temperatures on porous earthenware 

 blocks. They also develop on gelatine. 



NO. II 56. VOL. 45] 



The specific Schizomycete {Bacterititn vermi/orme, n. sp.) has 

 been very fnlly studied by the author. It occurs in the fermenta- 

 tions as rodlets or filaments, curved or straight, encased in a 

 remarkably thick, firm, gelatinous sheath, and is pronouncedly 

 anaerobic, so much so, that the best results are got by cultivating 

 it in carbon dioxide under pressure. 



The sheathed filaments are so like worms, that the name 

 proposed for the species is appropriately derived from this 

 character. 



It will not grow on gelatine, and separation cultures had to 

 be made in saccharine liquids by the dilution methods. 



It grows best in solutions of beet-root, or of cane sugar, with 

 relatively large quantities of nitrogenous organic matter — e.g. 

 bouillon, asparagin— and tartaric acid. Good results were ob- 

 tained with mixtures of Pasteur's solution and bouillon. 



The author found that the bacterium into which the filaments 

 subsequently break up can escape from its sheath and become 

 free, in which state it divides rapidly, like ordinary bacteria. 

 Eventually, all the forms — filaments, long rods, short rodlets — 

 break up into cocci. No spores have been observed. These 

 changes are dependent especially on the nutritive medium, but 

 are also affected by the gaseous environment and the temperature. 

 The jelly-like clumps of the so-called " ginger- beer plant" are 

 essentially composed of these sheathed and coiled Schizomycetes, 

 entangling the cells of Saccharomyces pyriformis. But the fer- 

 mentative actions of the Schizomycete on the saccharine medium 

 are difi'erent when alone, from those exercised when associated 

 with the yeast, or from those exerted by the latter alone. 



This was proved by cultivating each separately, and also by 

 cultivations in which, while each organism was submerged in the 

 same fermentable medium, they were separated by permeable 

 porcelain (Chamberland filters), through which neither could 

 pass. 



The author has also reconstructed the "ginger-beer plant " by 

 mixing pure cultures of the above two organisms ; the Schizo- 

 mycete entangled the yeast-cells in its gelatinous coils, and the 

 synthesized compound organism behaved as the specimens not 

 analyzed into their constituents. The symbiotic compound 

 organism so closely resembles a lichen, in its morphological 

 aspects, that it may be said to be a ferment-lichen. 



Some very curious phenomena in connection with the forma- 

 tion of the gelatinous sheaths and the escape of the bacteria from 

 them were observed in hanging-drop-cultures, and are figured 

 and described by the author. The conditions for the develop- 

 ment of the gelatinous sheaths — and therefore of the coherent 

 brain-like masses of the Schizomycete — are a saccharine acid 

 medium and absence of oxygen. The process occurs best in 

 carbon dioxide : it is suppressed in bouillon, and in neutral 

 solutions in hydrogen, though the organism grows in the free, 

 non-sheathed, motile form under these conditions. 



The behaviour of pure cultures of the bacteria in as complete 

 a vacuum as could be produced by a good mercury pump, worked 

 daily, and even several times a day, for several weeks, is also 

 noteworthy. The development of the sheaths is apparently in- 

 definitely postponed in vacuo, but the organism increased, and 

 each time the pump was set going an appreciable quantity of 

 carbon dioxide was obtained. In vacuum tubes the same gas 

 was evolved, and eventually attained a pressure sufficient to 

 burst some of the tubes. The quantity of carbon dioxide 

 evolved daily by the action of the bacterium alone, however, is 

 small compared with that disengaged when the organism is 

 working in concert with the symbiotic yeast ; in the latter case 

 the pressure of the gas became so dangerous that the author had 

 to abandon the use of sealed tubes. 



The products of the fermentation due to the Schizomycete 

 have not yet been fully determined in detail ; lactic acid, or 

 some allied compound, seems to be the chief result, but there 

 are probably other bodies as well. The author considers that 

 the bacterium removes from the sphere of action substances 

 which, if accumulated, would exhibit the fermentative power of 

 the yeast, hence the advantages of the symbiosis. 



The pink yeast-like form proved to be very interesting. It 

 has nothing to do with the "ginger-beer plant" proper, though 

 it was invariably met with as a foreign intruder in the specimens. 

 The author identifies it with a .form described by Hansen 

 in 1879 ("Organismer i Ol og Olurt," Copenhagen, 1879); 

 unfortunately the 'original is in Danish, but the figures are so 

 good that little doubt is entertained as to the identity. It is also 

 probably the same as Fresenius's Cryptococctis glutinis in one of 

 its forms. It is not a Saccharomycete, and does not ferment 

 like a yeast ; it is aerobian. 



