. Bacteria in relation to plant diseases. Bacteriology; Plant diseases. Fig. 21.* Fig. 22 t absolute accuracy by the use of Barber's apparatus, but no one seems to have made any exact experiments. Good organisms for experimental purposes would be Bacillus phytoph- thorus, Bacillus tracheiphilus, Bacillus amylovorus, â and Bacterium campestre, care being taken, of course, to select sensitive varieties and susceptible tissues, and to have all other factors comparable. SECONDARY TUMORS AND METASTASIS. Secondary foci of overgrowth occur in the olive and in the daisy as the result of internal infec
. Bacteria in relation to plant diseases. Bacteriology; Plant diseases. Fig. 21.* Fig. 22 t absolute accuracy by the use of Barber's apparatus, but no one seems to have made any exact experiments. Good organisms for experimental purposes would be Bacillus phytoph- thorus, Bacillus tracheiphilus, Bacillus amylovorus, â and Bacterium campestre, care being taken, of course, to select sensitive varieties and susceptible tissues, and to have all other factors comparable. SECONDARY TUMORS AND METASTASIS. Secondary foci of overgrowth occur in the olive and in the daisy as the result of internal infection. The writer has obtained them frequently in both plants by pure culture inocula- tions (plates 6 and 7, and fig. 23). The organisms pass through the tissues of the stems or leaves and set up irritations which lead to hyperplasias in particular spots in the deeper tis- sues. These tissue enlargements, later on, break through to the surface. Sometimes these secondary growths arise at a considerable distance from the primary tubercle. In case of olives inoculated in 1910 the writer observed numerous deep tubercles develop at a distance of I, 2, and 3 feet from the point of inoculation within a period of 7 months in actively growing plants, both down and up the shoot. The movement is more apt to be up the stem or leaf, i. e., with the transpiration current, than down the stem. In the olive a distinct channel of infection is traceable from the primary to the sec- ondary tubercle. This is usually (so far as observed) a narrow pathway in some part of the inner wood, the tissues being more or less stained and disorganized, and the bacteria present in abundance and easily demonstrable without staining. Whether similar downward *FiG. 21.âThree figures from Peirce's paper: (i) Two root-hairs of Bur clover infected by nodule bacteria, showing characteristic bending at point of infection, x 50. (2) The lower of two root-hairs in i, showing mass of bacteria in concavity of coil and in
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