CHARACTERISTICS OF THE COLON-AEROGENES GROUP 87 
pendent on the fermentation which produces the gas and it 
is, therefore, additional and important evidence of the validity 
of the distinction between the high and low ratio groups. 
Indol.—The formation of indol has always been associ- 
ated more closely with the fceal or B. coli type than with B. 
aeroyenes. The correctness of this assumption is indicated 
by the results shown in Table II and Fig. 2. Over 90 per 
cent of the low ratio cultures formed indol against 26 per 
cent for the high ratio cultures. This characteristic is evi- 
dently subject to some variation and the percentage of posi- 
tive results obtained depends in some measure on the technique 
adopted. 
TABLE IL 
PHYSIOLOGICAL REACTION OF NON-LIQUEFYING CULTURES, 
ALL SOURCES 
CO Low Ratio High Ratio 
Ilz Number | Per cent Number Per cent 
i 
INO! wacsss tee eaeite Gaaead Ga + 372 92.30 72 26.66 
= 31 7.69 198 73.383 
Saccharose ..............-. + 157 39.05 248 91.85 
> 245 FAY. 94 22 3.14 
Raffinose .........6-2200 00s + 173 43.14 \ 246 90.77 
_ 228 36.85 25 9.22 
SEACH: .ceseisscreisis seccasseaaieiaines + 24 6.16 133 50.57 
_ 365 93.83 130 49.42 
TONER desler cayenne Ee + 1 .29 16 7.30 
_ B42 99.70 189 92.19 
Mannitol] .......-.-.0+-.46+ + aT 99.00 171 64.77 
— 4 99 93 35.22 
GI GOTO] cee nadie esses + o2t 93.58 140 68.63 
_ oy 6.41 64 31.37 
SACI: |. 24. disor eaty + 197 74.06 255 95.86 
_— 6) 25.93 11 4.13 
DileitOl, se snciotsionye sete + 205 51.25 86 Shs 
— 195 48.75 185 68.26 
Adonitol .......-..0eee ee ree + 53 15.45 137 49.28 
— oo) $4.54 141 50.71 
A perfect correlation with the more basic characters could 
not be expected but so far as the evidence goes it forms 
another distinction between the low and high ratio group. 
