373 



Variation in Bacillus coli. — The Production of Two Permanent 

 Varieties from one Original Strain by means of " Brilliant 

 Green." 



By Cecil Revis. 



(Communicated by Sir J. R. Bradford, K.C.M.G., Sec. R.S. Received April 8, — 



Read April 24, 1913.) 



In a former communication* it was noted that a profound change in 

 physiological activity could be brought about in some strains of Bacillus coli 

 by growth in the presence of Malachite Green. This change consisted in the 

 complete loss of power to produce gas in the usual test media, the action 

 ceasing at the acid stage. 



Similar experiments have been carried out using Brilliant Green in place of 

 Malachite Green, and many interesting results have been obtained. The 

 following is of particular interest in that two permanent varieties arose from 

 one original organism under precisely similar circumstances. The method 

 employed was exactly the same as in the former experiments. The culture 

 used was repeatedly plated until it was evident that the final culture used 

 had arisen from one single organism. This procedure is undoubtedly better 

 and less liable to error than some of the more complicated methods which 

 have been proposed (cp. Eisenbergf). 



The properties of the original culture were : — 



Milk Coagulated in 48 hours. 



jLactose peptone water + + + „ „ 



Sucrose „ 



Adonitol „ 



Dulcitol ., + + + + on 5th day. 



Inulin ,, 



Glucose „ ...... + + + in 48 hours. 



Salicin „ + on 5th day. 



Mannitol „ + + + + in 48 hours. 



This selected culture was then inoculated into nutrient broth ( + 1) 

 containing 0*004 per cent, of Brilliant Green. Two different inoculations 



* Revis, ' Roy. Soc. Proc.,' 1912, B, vol. 85, p. 192. 



t Eisenberg, 'Cent, fiir Bakt.,' 1912, Abt. I, vol. 63, p. 305. 



I The positive sign indicates the production of acid and gas in the test medium, using 

 5 c.c. medium and a gas tube inch diameter. The signs + , + + , + + + , and + + + + 

 indicate «, j, 2, and -f inch of gas in the tube. No change, thus . 



VOL. LXXXVI. — B. 2 E 



