. A text-book of bacteriology; a practical treatise for students and practitioners of medicine. Bacteriology. 410 PATHOGENIC MICROORGANISMS from the feces by the use of the Endo fuchsin-agar. Emulsions of feces are made in tubes of ordinary broth in the manner described in the Con- radi-Drigalski method, and smears of this emulsion are made upon plates of the fuchsin-agar by means of a glass smearing rod. The colonies of Bacillus coli, after eighteen or more hours of incubation, will be found to have brought back a deep red color to the medium, whereas the typhoid colonies are smaller, more tr
. A text-book of bacteriology; a practical treatise for students and practitioners of medicine. Bacteriology. 410 PATHOGENIC MICROORGANISMS from the feces by the use of the Endo fuchsin-agar. Emulsions of feces are made in tubes of ordinary broth in the manner described in the Con- radi-Drigalski method, and smears of this emulsion are made upon plates of the fuchsin-agar by means of a glass smearing rod. The colonies of Bacillus coli, after eighteen or more hours of incubation, will be found to have brought back a deep red color to the medium, whereas the typhoid colonies are smaller, more transparent, and have left the medium uncolored. In all cases where plates are prepared from broth emulsions of feces, it is desirable to allow the emulsion to stand at incubator temperature for several hours, or, better, to centrifugalize the emulsion and then allow it to stand without agitation. Subsequent removal of fluid from the. Fig. 92.—Colon and Typhoid Colonies in Hiss Plate Medium. (Planted from stool. Note the small thread-forming typhoid colonies.) upper layers of the medium is likely to bring away a comparatively larger number of the motile organisms. The methods of isolating typhoid bacilli given above do not ex- haust the records of work done upon this problem. Other methods have been devised, but those given are the ones most generally in use. It is not satisfactory to compare any two of these methods as to practical value, since all of them require a considerable amount of working famil- iarity with organisms and media. In fact, it may be said that all of the methods given are satisfactory if consistently employed by a worker who has become thoroughly accustomed to the peculiarities and variations of the typhoid colonies upon the medium with which he is 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
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