125 
A PRELIMINARY NOTE ON THE SUPPOSED 
BACTERICIDAL INFLUENCE OF FLOUR 
AND ALLIED SUBSTANCES ON 
BACILLUS TYPHOSUS 
By HERBERT E. ROAF, M.B. (Tor.) 
COLONIAL FLLLOW 
THE following experiments were performed to follow out some results obtained 
by Klein and Houston 1 : — Both these observers used media composed of 
flour, oatmeal, and ground rice in a ten per cent, emulsion. The media were 
inoculated with various bacteria, and inoculations were made from them at definite 
intervals. According to the length of time that the bacteria could be demonstrated 
it was judged if there was any bactericidal effect. No mention was made, however, 
of control experiments with sterilized water. They found that in a wheat-flour 
medium, B. typhosus was absent after three to five days ; B. dipbtheriae after one day ; 
S. pyogenes aureus after thirteen to twenty-four days ; V. cbolerae after three to six 
days, and B. pyocyaneus after fourteen days. That in oatmeal, B. typhosus was absent 
after six days ; B. dipbtheriae after one day ; V. cbolerae after two days ; and B. pyo- 
cyaneus after four days. In ground rice, B. typhosus was absent after twenty-five days ; 
B. dipbtheriae after three days ; V. cbolerae after two days, and B. pyocyaneus after 
twenty-nine days. 
In the following series of experiments I employed the B. typhosus. The 
media consisted in most cases of a ten per cent, emulsion of wheat flour. In some 
of the experiments the material was filtered through a sterilized Pasteur-Chamber- 
land filter in order to free it from contaminating organisms. 
In two experiments the filtered juice obtained from potatoes and apples was 
used, and lastly, sterilized water was employed as a control. The medium was in 
each case inoculated with a pure culture of B. typhosus, and a culture was immediately 
made vising one c.c. of the mixture. This was either plated immediately or diluted to 
some sub-multiple of ten and one c.c. of the dilution used. The material used for 
plating was neutral red taurocholate lactose agar 2 . The plates were incubated, 
and after twenty-four hours the white colonies were counted. If the colonies were 
too numerous to be counted they were marked thus oo. 
I. Report on the Behaviour of Specific Microbes in Relation to Cereal Products. Local Government Reports, 30th Annual Report. 
2. Grunbaum and Hume, British Medical Journal, 1902, 1, p. 1+73. 
