. Bacteriological methods in food and drug laboratories, with an introduction to micro-analytical methods. Bacteriology; Food; Drug adulteration; Bacteriology. IOO BACTERIOLOGICAL METHODS the streptococci), it is desirable to examine such colonies micro- scopically and to inoculate into other media and perhaps to test for indol formation, in order to obtain satisfactory proof as to whether or not they are colon bacilli. Neutral red (a safranine dye) reduction was at one time con- sidered a very important check test for the colon group. Stokes, as early as 1904, recommended that neutral red be
. Bacteriological methods in food and drug laboratories, with an introduction to micro-analytical methods. Bacteriology; Food; Drug adulteration; Bacteriology. IOO BACTERIOLOGICAL METHODS the streptococci), it is desirable to examine such colonies micro- scopically and to inoculate into other media and perhaps to test for indol formation, in order to obtain satisfactory proof as to whether or not they are colon bacilli. Neutral red (a safranine dye) reduction was at one time con- sidered a very important check test for the colon group. Stokes, as early as 1904, recommended that neutral red be added to lactose j bratk in the fermentation tubes which contain the required dilu- >- 69 fr: J2 as eg =3 3 —: CD TZ CO JET c* CO < CO -J. Fig. 27.—B. coli showing flagellar stained by the van Ermengen method (X 1000).—(MacNeal, from McFarland after Migula.) tions of the liquids to be examined. 30 to 50 per cent, gas forma- tion in the closed arms of the tubes and the change of the neutral red to canary yellow, is said to be characteristic for the colon group. It would appear that the majority of bacteriologists are inclined to omit the neutral red test as being of little value. The production of indol in peptone broth or solutions is another colon bacillus test much used in the United States. Boehmes' modification of the Ehrlich method is now generally employed, made as follows: Two solutions are Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Schneider, Albert, 1863-1928. Philadelphia, P. Blakiston's Son & Co
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