372 SUMMARY OF CURRENT RESEARCHES RELATING TO 



enables it to dissolve and decompose coagulated albumen. Its ester- 

 formation is strongly evinced on all media. It attacks albumen and 

 carbohydrates simultaneously, and produces sucb a quantity of ammonia 

 from the albumen that the acid formed from the carbohydrates is neutra- 

 lised at once, and the reaction of the medium remains neutral. B. prae- 

 pollens splits up urea and decomposes nitrites with production of free 

 nitrogen. To milk it imparts a very agreeable aroma. 



Dextran-forming Bacteria.* — Herr F. W. J. Boekhout had his 

 attention called to dextran-forming bacteria by the mucoid coagulation 

 of milk to which 8 per cent, cane-sugar had been added. From the 

 slimy fluid was obtaiued a streptococcus, Str. hornensis, which is endowed 

 with the power of converting saccharated media into a mucoid mass. 

 Dextran-formers occur not only in milk but in water and on flowers. By 

 inoculating bouillon and gelatin containing 20 per cent, cane-sugar by 

 means of flower-blossoms, several varieties of dextran-forming bacteria 

 were obtained. Only one of these, Str. hornensis, receives attention. 

 This organism stains well with aniliu dyes. It was cultivated on solid 

 and in liquid media containing cane-sugar. On the former the growth 

 was white, gelatinous, and placentiform ; while liquid media are converted 

 into a slimy or gelatinoid fluid according to the less or greater amount 

 of sugar. Its optimum temperature lies between 22° and 30° 0. It is a 

 potential anaerobe. Experiments with pepton, asparagin, ammonium 

 tartrate, calcium nitrate, and ammonium sulphate, showed that pepton 

 only was utilised as a source of nitrogen. It was also determined in a 

 similar way that cane-sugar was the most [suitable carbohydrate. The 

 organism was killed in 5 minutes at 55°. The mucoid substance was 

 obtained by cultivating on a saline medium containing pepton and cane- 

 sugar ; from this it was precipitated by means of alcohol and dried. 

 Treated with sulphuric acid the substance was inverted, the sugar being 

 right-turning and reducing. Hence the inverted mass must be 

 dextrose and the previous substance dextran. 



Coal Bacteria. | — M. B. Benault gives an account of some new 

 bacteria found in coal. 



(1) Bacillus colletus. The cells are short with rounded ends; there 

 is marked tendency to form chains ; reproduction usually takes place by 

 arthrospores. 



(2) Another bacterium, found, like the foregoing, in Arthropitus wood, 

 is about 1*8^ long and • 5 a broad ; the ends are conical and the 

 membrane is well denned and dark coloured. This bacterium, which 

 often forms chains of three links, is associated with Bacillus carbo. 

 This latter is observed in the cells and vessels, is 2 • 2-4 /a long, does 

 not form arthrospores, and rarely chains. Attention is then called to 

 the frequent presence in coal of transparent vacuoles of variable size and 

 shape. They impart the impression of being gas-bubbles, imprisoned in 

 a dried-up viscid substance. 



Besides bacteria which have contributed to its formation, coal also 

 contains microbes which have penetrated the vegetable tissues before its 

 transformation into coal ; and the. occurrence in coal from St. Etienne of 



* Centralbl. Bakt. u. Par., 2" Abt., vi. (1900) pp. 161-5 (1 fig.). 



t Comptes Reiidus, cxxx. (1900) pp. 740-2. Cf. this Journal, 1898, p. 461. ' 



