1364 Wisconsin Academy of Sciences, Arts, and Letters. 
Bacteria fermenting lactose with the formation of gas—oolon- 
like bacilli—were found to be distributed in the various grades of 
milk as follows: 
Raw milks gas in 
Raw milks gas in 
Inspected milks gas in 
Inspected milks gas in 
Certified milks 
Pasteurized in bulk, gas in 
Pasteurized in bulk, gas in 
Pasteurized in bottle, gas in 
Pasteurized in bottle, gas in 
83% of 1/100 c. c. sample 
71% of 1/1000 c. c. sample 
54% of 1 c. c. sample 
30% of 1/100 c. c. sample 
0% of 1 c. c. sample 
83% of 1 c. c. sample 
25% of 1/100 c. c. sample 
4% of 1 c. c. sample 
0% of 1/100 c. c. sample 
Endo’s medium was found to be only fairly satisfactory as a 
means of detecting colon-like organisms in milk, especially 
where as much as 1 cubic centimeter of milk needs to be used. 
Endo plates run with fermentation-tube test obviate the possi¬ 
bility of confusing coli with anaerobic bacteria capable of fer¬ 
menting lactose, since such organisms do not grow similar to B. 
coli on the Endo plates. 
Bact. Welchii was found to be present in considerable numbers 
in raw milks, 3.2 being the average number found to each 20 c. c. 
It was found with practically equal frequency in pasteurized 
milks, less frequently in inspected milks, and rarely if ever in 
certified. Apparently one such spore per 20 cubic centimeters of 
milk is of little significance, but a greater number, such as three 
or four per c. c. would seem to be a good indication that a milk is 
rather seriously contaminated. The presence of this germ in con¬ 
siderable quantities in pasteurized milk is apparently a good indi¬ 
cation that the milk used for the purpose of pasteurization is 
seriously contaminated. This method seems, then, to be especially 
useful where a pasteurized milk is under investigation whose con¬ 
dition in a raw state was unknown. On this account, and for this 
purpose, the use of this method merits further study. 
Tiie number of spores, or those forms capable of resisting a 
temperature of 80° C. for ten minutes, furnishes data of value in 
connection with the other facts in regard to a particular milk, 
e. g., a raw milk having a high total count and a low spore count 
has probably not been kept at a temperature sufficiently low, 
or if it has been kept at a low temperature, not for a long enough 
time to allow germination and growth; a high spore count in a 
pasteurized milk indicates either a poor raw milk, a low pasteur¬ 
izing temperature, or a contamination with heat-resisting forms 
