342 IVAN C. HALL AND LILLIAN J. ELLEFSON 



any trace of gas in five days. Inasmuch as only one of the 19 

 heated samples showing gas in the test without the dye produced 

 acid on the lactose agar plate, due incidentally to B. coli which 

 was isolated and must be considered to have escaped the heat- 

 ing, we are justified in the statement that at least 90 per cent of 

 these samples contained gas forming sporebearing anaerobes, 

 and considering the two series of tests, we can say that only one 

 of the whole 20 samples failed both times to show gas necessarily 

 interpreted as due to anaerobic sporebearing bacilli; in other 

 words 95 per cent of these particular samples contained organ- 

 isms in addition to B. coli, capable of giving rise to a positive 

 presumptive test in lactose broth without gentian violet. The 

 organisms growing upon the litmus lactose agar plates, though 

 non-acidifying, barring the one sample in which B. coli was 

 found, were stained by Gram's method and were found in every 

 case to be Gram-positive sporulating bacilli of the hay bacillus 

 group. 



All the unheated samples showed gas in the standard pre- 

 sumptive test as against 15 in the gentian violet lactose broth. 

 The proportion showing acid colonies from each set was approxi- 

 mately one-third — considerably lower than in the first series, 

 owing to the disappearance of B. coli from some of the samples 

 on standing. Notwithstanding the low proportion of samples 

 showing acid colonies, we were able to isolate B. coli from 13 

 of the 15 showing gas in dye broth and from 14 of the 20 show- 

 ing gas in plain lactose broth. One sample showing B. coli in 

 the standard test failed to show it in the dye test. From the 

 other sample showing gas in gentian violet lactose broth a cul- 

 ture tentatively designated as B. cloacae was isolated. This 

 organism, as usually described, differs from B. coli only in pos- 

 sessing the ability to liquefy gelatin. We have had a number 

 of such cultures which will be mentioned in the further discus- 

 sion. In each case we have attempted, and usually successfully, 

 to separate such cultures into subcultures, one of which liquefies 

 gelatin and does not ferment lactose, the other of which fer- 

 ments lactose and does not liquefy gelatin; in other words, B. 

 coli. The principal organisms thus separated from B. coli have 



