File:On a Bacterial Disease of the Turnip (Brassica napus) (1900) (14760095961).jpg

Identifier: philtrans01418352 (find matches)
Title: On a Bacterial Disease of the Turnip (Brassica napus)
Year: 1900 (1900s)
Authors: Potter, M.
Subjects: Proceedings of the Royal Society of London Philosophical Transactions of the Royal Society
Publisher: Royal Society of London

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r development ispossible; growth, however, is resumed when the oxalic acid is neutralisedby a calcium salt. The reaction between the oxalic acid produced byP. destructans and the calcium pectate of the middle lamella ispreeiselly analogous: the oxalic acid would be neutralised, and thepectate replaced by the oxalate, and the continued growth of thebacteria would thus be rendered possible. The oxalic acid* then bothacts as a toxin in killing the cells and may also play some part in # Since the above account of the formation of oxalic acid by P. destructans waswritten, Zopf has published a note also describing the formation of oxalic acid hyB. xyliiiuni) u Oxalsaurebildung durch Bacterien, Berichte d. D. Bot. G-esell./Feb. 1900. 2k2 452 Prof. M. C. Potter. On a Bacterial the destruction of the middle lamella and the separation of thecells. Fig. 5 shows a cell swarming with 1\ dedrudans; the bacteria areseen occupying the inter-cellular spaces and lying in the track of themiddle lamella.
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Fig. 5.—A cell from turnip inoculated with a pure culture of P. destructans.The bacteria are seen in the cell cavity and also along the track of themiddle lamella, and in the intercellular spaces. The cell-wall is muchswollen ; at a it is just beginning to separate along the middle lamellaand at b the dissociation is more strongly marked. The nucleus andportions of the protoplasm still remain. (Drawn with Abbe cameralucida, Zeiss, E. oc. 4.) Iii the case of several parasite fungi, the hyphge also burrow in thethickness of the cell-wall, and the same phenomenon is now shown tobe true of one parasitic schizomycete, and possibly this is owing tothe necessity for the neutralisation of the oxalic acid as a condition ofexistence. Enzymes similar in nature to that described for F, dedrudans havebeen demonstrated by Marshall Ward for Botrytis and by de Bary forSclerotinia. The action of this bacterium upon living plant tissues is preciselysimilar to that of certain of the parasitic fungi; i

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