. Bacteria in relation to plant diseases. Bacteriology; Plant diseases. 82 BACTERIA IN RELATION TO PLANT DISEASES. per gallon. The wrouglit-steel C3'linders cost about $io each. A good quality of test-tubes may be had from Greiner & Friedrichs, Stiitzerbach, Germauy. One sort has a faint-blue longitudinal stripe blown into the glass, another kind has the letter " R " etched on the upper part of each tube. Tubes without any distinguishing mark should not be purchased, as they are likely to become mixed with ordinary non-resistant tubes. The cost of these tubes, du
. Bacteria in relation to plant diseases. Bacteriology; Plant diseases. 82 BACTERIA IN RELATION TO PLANT DISEASES. per gallon. The wrouglit-steel C3'linders cost about $io each. A good quality of test-tubes may be had from Greiner & Friedrichs, Stiitzerbach, Germauy. One sort has a faint-blue longitudinal stripe blown into the glass, another kind has the letter " R " etched on the upper part of each tube. Tubes without any distinguishing mark should not be purchased, as they are likely to become mixed with ordinary non-resistant tubes. The cost of these tubes, duty free, is about $ r 6 per thousand. Good Petri dishes may be obtained from the same firm, and also from E. H. vSargent & Co., Chicago. The temperature demands of bacteria are extremely variable. Whole groups of them are able to live under conditions which would be impossible for the higher. Fig. 68.* plants and animals. Many of the northern forms, especially those which grow in water, are adapted to low temperatures. The organisms of dung-heaps and thermal springs, and the tropical forms, often grow at high temp)eratures. For a very few species it has been known that prolonged freezing or repeated freezing and thawing destroys the weaker individuals and finally all. (See Bibliog., XXXIII, especially papers by Sedgwick & Winslow, and b)' Park; consult also an earlier paper by Prudden, Pjibliog., XIvVI.) E'er the bacteria as a whole, however, it has been assumed that ordinary freezing or even very intense cold simph- inhibits *FiG. 68.—Pctri-dish poured plate of Bacillus trachcipliihis. The lo cc. of nutrient agar was inocuUiteil with a carefully measured loop of a fluid culture. The fluid culture was then exposed in block-tin test-tubes to the temperature of liciuidair, after which another plate (fig. 69) was Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of
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