. Laboratory work in bacteriology. Bacteriology. GELATIN AND POTATO MEDIA. 173 The platinum wires are sterilized by holding them in the flame, till incandescent. The end of the glass rod should always be thoroughly heated, and, if any organic matter is present, such as gelatin, it should be burned off. The wires should be kept in a conical test-glass (Pig. 43), in the bottom of which is some Fig. 29. The inoculation of a single tube. Place three of the sterilized, gelatin tubes in a water- bath which has been warmed to about 30-35°. When the gelatin melts, the tubes are ready for inoc


. Laboratory work in bacteriology. Bacteriology. GELATIN AND POTATO MEDIA. 173 The platinum wires are sterilized by holding them in the flame, till incandescent. The end of the glass rod should always be thoroughly heated, and, if any organic matter is present, such as gelatin, it should be burned off. The wires should be kept in a conical test-glass (Pig. 43), in the bottom of which is some Fig. 29. The inoculation of a single tube. Place three of the sterilized, gelatin tubes in a water- bath which has been warmed to about 30-35°. When the gelatin melts, the tubes are ready for inoculation. With a sterilized, cooled platinum wire, pick up a minute amount, of the growth on potato, of the Bacillus prodigiosus. Place one of the liquefied gelatin tubes between the thumb and index finger of the left hand, so that it is almost horizontal. It is held in this position in order to prevent foreign matter from dropping into the tube. The neck of the tube with its plug, as well as the palm of the left hand, is turned to the right. In this position the entire length of the tube is be- fore one's eyes (Fig. 29). While still holding the platinum wire in the right hand, grasp the cotton plug with the little finger of that hand, and, remove it by slight rotation. If any tufts of cotton are adherent to the neck of the tube, touch it for a moment to a Bunsen flame. Otherwise, the platinum wire might carry in some of this material, and thus cause unnecessary contamination. As a matter of rou- tine, it is well to always flame the neck of a tube before insert-. 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 Novy, Frederick George, 1864- . Ann Arbor [Mich. ] G. Wahr


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