. Bacteria in relation to plant diseases. Bacteriology; Plant diseases. CULTURE MEDIA. 97 PREPARATION AND CARE OF CULTURE SIEDIA. Everything should be carefully weighed or measured. Everything should be clean as possible to begin with. By water is usually meant distilled water, and this should be free from copper or other germicidal metals (see Bolton, Bibliog., XXXVIII). Moore & Kellerman have shown very recently that the Bacillus typhosus is destroyed in distilled water if the merest trace of metallic copper is present. Water swarming with this organism was sterilized simply by standing
. Bacteria in relation to plant diseases. Bacteriology; Plant diseases. CULTURE MEDIA. 97 PREPARATION AND CARE OF CULTURE SIEDIA. Everything should be carefully weighed or measured. Everything should be clean as possible to begin with. By water is usually meant distilled water, and this should be free from copper or other germicidal metals (see Bolton, Bibliog., XXXVIII). Moore & Kellerman have shown very recently that the Bacillus typhosus is destroyed in distilled water if the merest trace of metallic copper is present. Water swarming with this organism was sterilized simply by standing three hours in a copper vessel. The writer found the count of Bacillus tracheiphilus reduced over 30 per cent by exjDOSure in bouillon in block-tin tubes for twenty-one hours. Exposure for forty-eight hours gave the same result, /. <?., 33 per cent destroyed. A simple glass still is shown in fig. 82. As far as possible the chemicals should be. Fig. 82.* c. p., and in many cases it is necessary to make the test for oneself, no matter what the reputation of the firm or the statement on the label. When possible, broken packages should be avoided. It is therefore best to procure most chemicals in several small packages rather than in one large one. If the preparation of culture media is broken off before its completion, by nightfall or interruptions of any kind, the unsterilized or incompletely sterilized media should be put into the ice-box, especially if it is warm weather. Neglect of this precaution frequently results in the spoiling of the media. In steam sterilization one should begin to count time only after the thermometer registers 100° C, or at least 99° C. Those who live in high *FiG. 82.—Portion of a work-talile showing method of distilling water for use in making culture media. The flasks should be insoluble glass. The cold hydrant water passes through the condenser in the direction of the arrow. In actual use the upright flask and the flame are sheltered from ai
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