212 SUMMARY OF CURRENT RESEARCHES RELATING TO 



serves to distinguish various strains of bacteria that do not grow with 

 the same activity, and to detect the increased or diminished vitality of 

 cultures, and it also allows one to estimate the value of different media ; 

 the energy of the reduction is measured by the depth of the pink zone. 

 The rapidity of the reduction is not proportionate to the pathogenic 

 virulence of the organism, but depends on the number of the organisms 

 present. The reaction is favoured by a temperature of 35° 0. The 

 author suggests that this reaction might be useful in detecting the 

 presence of microbes in liquids in which on microscopic examination their 

 presence could not be detected. 



New Chromogenic Slime-producing Organism.* — F. C. Harrison 

 and B. Barlow isolated from oily butter a chromogenic microbe that 

 formed slime and crystals, and to which they gave the name B. visco- 

 fucatus. The organism is a non-motile rod, 1 * /x-1 ■ 8 /x long by 

 * 6 n-0 ' 9 /a broad, occurring singly or in chains, with a tendency to 

 pleomorphism ; after the formation of slime a capsule was observed ; 

 no spore formation was noted ; it stains by ordinary dyes and by 

 Gram's method. On gelatin plates to which various carbohydrates 

 were added, the colonies after five days were 1 mm. in diameter, and 

 liquefaction had commenced ; the colonies were slimy, and much pig- 

 ment had developed, showing blue or violet with sucrose, dextrose, 

 mannite, and maltose, and green with galactose, dextrin, and starch ; 

 gelatin without carbohydrates developed only a yellow-green tint. On 

 agar it formed white slimy colonies, but no pigment ; on 1-20 p.c. 

 sucrose agar there was a deep blue pigmentation. In milk, after 

 25-40 hours at lS°-22° C, there appears a grey-blue coloration, which 

 becomes bright blue and later disappears ; there is much slime pro- 

 duced, and late peptonisation of the medium. On potato at 22° C. it 

 forms a yellowish-white slimy growth, the medium becoming a bright 

 dark-blue after 4-5 days, and later becoming ochre-yellow or rust 

 colour. The pigment was extracted from an agar culture in 50 p.c. 

 alcohol, the solution being blue to wine colour ; it was soluble in 

 water, but not in benzin or chloroform. The slime after separation 

 was soluble in cold water, and after heating with dilute acid it re- 

 duced Fehling's solution. 



Bacteria that obtain their Carbon from Methanf. — N. L. Sohngen 

 has demonstrated that the absorption of methan by plant life is due to 

 a micro-organism. By means of an arrangement of two Erlenmeyer 

 flasks, and a special carbon-free fluid medium (which he inoculated with 

 slop- water or grave- water, and to which he admitted a known mixture of 

 oxygen and methan, the whole being placed at 30°— 37° C.) he obtained 

 after 2-4 days a pellicle growth ; on analysing the gaseous mixture 

 when the culture was a week old, he found that the methan had entirely 

 or partly disappeared,, whereas an appreciable amount of C0 2 had been 

 produced. The bacterial pellicle was composed chiefly of one variety of 

 bacterium : short stout rods, motile only in young cultures, provided 

 with one flagellum. This organism the author has named B. methanicus ; 

 by growing this bacterium in his apparatus he was able to show that 

 methan was the only source from which it could obtain carbon. 



* Centralbl. fcakt., 2te Abt., xv. (1905) p. 517. t Tom. cit., p. 513. 



