o62 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Action of Absolute Alcohol on Bacteria and on Yeasts.* — E. C. 

 Hansen experimented on the action of ethyl alcohol on yeasts and on 

 certain bacteria, viz., J>. cofo'and B. pasteurianus. The organisms were 

 collected on a platinum wire and thoroughly spread in a line layer over 

 the inside of a sterile flask, and after standing 24 to 4H hours in the 

 dark at room temperature, the cells were regarded as dried ; these were 

 then treated witli absolute alcohol, and it was found on every occasion 

 that after one minute the cells still lived and could be cultured in broth, 

 and in two cases the cells survived the action for eight minutes. By 

 using 60 p.c. to 50 p.c. alcohol all the cells were killed within one 

 minute, and the same result was obtained when undried cells were 

 treated with absolute alcohol. From these results it is shown that 

 bacteria in a moist state have a less resistance to absolute alcohol 

 than when they are dried ; the dried wall of the cell must take up water 

 before the alcohol can penetrate the cell substance. Referring to the 

 different results obtained by other observers, the author accounts for 

 these by the methods employed, and lays stress on the proper drying of 

 the cells by thoroughly spreading in thin layers. In some cases a sur- 

 rounding mucus capsule will protect the organism from the action of the 

 alcohol. 



Blue Pigment produced both by a Diphtheroid Bacillus and by a 

 Streptothrix.f — E. Miiller isolated from a serum plate culture, made 

 from a swab from a tonsil, a diphtheroid bacillus which produced a light 

 blue colour on potato and in milk, but not on agar or on gelatin. The 

 organism presented most of the characters of the diphtheria bacillus, 

 but was not pathogenic for guinea-pigs. The author has named it 

 B. mlkolor. A year later the author found on an unused potato-tube 

 a Streptothrix colony, surrounded by an intense blue-coloured area. 

 Grown on thin layers of medium beautiful concentric rings were formed, 

 and are represented in a number of illustrations accompanying the 

 description of the organism. These ring colonies are formed by zones 

 of growth with aerial hyphge alternating with zones where the hyphae 

 are absent. The author has named this organism Streptothrix ccelicolor. 

 It grows well at room temperature and at 86° C. ; it is an obligate 

 aerobe ; it has a characteristic earthy smell ; gelatin is liquefied without 

 production of the pigment ; milk is peptonised without the formation 

 of acid or pigment. The author considers the blue pigment is identical 

 in these two organisms ; it is only formed at temperatures below 30° C, 

 and in the presence of oxygen ; its formation is apparently caused by 

 the action of the organism on the starch of the potato, and on some 

 molecular complex nearly allied to the starch molecule that may be 

 present in the media in which this pigment appears. The author has 

 named this pigment amylocyanin ; it is soluble only in water ; spectrum 

 examination shows a strong absorption of light between the D line and 

 the green, and a fainter absorption at either side extending to the C and 

 E lines respectively. 



* Centralbl. Bakt., lte Abt. Orig., xlv. (1907) p. 466. 

 t Op. cit., xlvi. (1908) p. 195. 



