10 E. M. MEYER 



from the confirmatory Endo's medium plate, made from the 

 lactose broth tube inoculated with the water sample. The 

 colony is inoculated into lactose broth, to confirm gas produc- 

 tion, and if this tube is positive the organism is again plated on 

 Endo's medium to determine if it be pure. If this plate reveals 

 the presence of but one form, a colony is fished to an agar slant. 

 A smear from the culture on the slant, after forty-eight hours' 

 growth at 37°C., is stained by Gram's method, and if only Gram- 

 negative, non-spore-forming bacilli are seen, the culture is con- 

 sidered pure and made up of B. coli. 



Following the above outlined procedure, eight cultures from 

 one source^ were found which gave gas in lactose broth, but which 

 on the agar slant grew very differently from B. coli. They 

 appeared on staining to be large Gram-negative, fusiform rods 

 containing spores, together with large Gram-negative vegetative 

 bacilli. For some time the writer was under the impression, 

 gained through previous experience, that this spore-bearer was 

 a contamination form and that the gas production would finally 

 be found to be due to B. coli. Accordingly, attempts were made 

 to purify the culture by plating on Endo's medium, agar and 

 gelatine. The colonies on all of the media appeared to contain 

 but one organism. When transferred to agar slants the growth 

 was macroscopically and microscopically Uke the agar slant cul- 

 ture first alluded to. That the gas production was due to the 

 spore-forming organism was definitely proved by the heat- 

 resistance experiments next performed. 



RESISTANCE TO HEAT 



The organism will live and generate gas in lactose broth after 

 being subjected to 95°C. for twenty minutes or to boiling water 

 temperature for ten minutes, but is killed if subjected to the 

 latter temperature for fifteen minutes. The writer has been 

 checked in these results by another bacteriologist in this labora- 



2 Since the writing of this article the organism has been isolated three addi- 

 tional times — once from the tap water of Covington, Ky., and twice from raw 

 tannery trade wastes. These three cultures resemble the eight previously iso- 

 lated in all particulars. 



