1 7 2 FERMENT A TION IN MILK 



coloration was due.^ In the year 1896, however, M. Zangmeister, 

 working on the same subject, claimed to have isolated ^ a micro- 

 organism which, although resembling in many respects the Bacillus 

 cyanogenes, presented certain morphological and cultural properties 

 sufficient in his opinion to differentiate it from that of former 

 workers in the same field. To this he gave the name of Bacillus 

 cyaneo-fiuorescens, a description of which will be found in a subse- 

 quent chapter (p. 430). It has been asserted that the Bacillus 

 jantJiinus of Zopf has the power of colouring milk blue or bluish- 

 violet. 



The Bacillus cyanogenes {Bacterium syncyaneum of Ehrenberg) 

 or as Hueppe originally termed it, the Bacillus lactis cyanogenus, 

 is an anaerobic, non-liquefying, bacillus motile, bi-polar, flagellated, 

 chromogenic, and round-ended with a varying average length of 

 from I to 4 mm. by -3 to -5 mm. in breadth. Spore formation has 

 been claimed by Hueppe and others, but this is denied by Heim, 

 who describes the so-called spores of Hueppe as involution forms 

 only. A careful investigation by the authors, and the fact that 

 these so-called spores cannot withstand a temperature of 80° C. for 

 more than one minute, would tend to confirm this view. In liquid 

 cultures curious involution forms are often observed, which are 

 especially noticeable if the organism is grown in mineral media, 

 as those of Conn and Nsegeli. 



The organism does not liquefy gelatine and grows freely 

 on all the usual laboratory media at room temperature, the 

 dark purplish blue or in some cases brownish coloration of the 

 medium being very characteristic, but this freedom of growth 

 becomes less as the temperature advances to 37° C, and the cul- 

 tures themselves die at 40°. The reaction is invariably alkaline, 

 although the medium itself may have been in the first place acid. 

 It stains well with all the ordinary stains but does not hold the 

 Gram. 



In milk the bluish tint would appear to be dependent upon 

 certain conditions, and in the sterile milk used for the laboratory 

 purposes it is not easy to obtain it " in vitro." 



^ It is well here to note that a certain blue or bluish coloration of milk when 

 freshly drawn has been attributed by certain investigators to the fact of thje cow 

 having partaken when in pasture of one of the Butomacse {Butoinus umbellatus), 

 a not uncommon plant on water meadows and which contains a blue pigment 

 of the nature of indigotin. The authors, however, have never been able to trace 

 an authentic case of blue coloration of milk to this cause. 



^ Centralb.f. Bakt, i sec. XVIII., p. 321. 



