Observations on a hitherto unreported bacterial disease the cause of which enters the plant through ordinary stomata / by Erwin F. Smith.

  • Smith, Erwin F. (Erwin Frink), 1854-1927.
Date:
1903
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Licence: In copyright

Credit: Observations on a hitherto unreported bacterial disease the cause of which enters the plant through ordinary stomata / by Erwin F. Smith. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    rounded, pale-yellow, gum-like masses, which ooze from the stomata lying over the closed bacterial cavity. The infec- tions take place principally in May and June, and no wounds are necessary. The shaded and west side of the fruits are most subject to infection, i. e., those on which the rain drops or dew drops (neces- sary for infection) would persist longest because best protected from the morning sun. This is primarily a disease of the parenchyma, but the bundles are finally invaded. The organism is distinctly yellow and grows readily in ordinary culture media, bouillon, milk, potato, agar, etc. It was easily obtained in pure culture from small spots. In agar plate cultures it looks much like P. campestris, but is readily distin- guished by its feebler growth on potato and by its behavior in Uschinsky’s solu- tion, which is converted by it from a limpid fluid to one as viscid as egg al- bumen. The bacteria are small to medium size and occur singly, in pairs or short chains. They are motile by means of one to several polar flagella. The thermal death point is approximately 51° C. Gela- tin is not liquefied rapidly. Litmus in milk is reduced, but finally returns to its v former color. Casein is slowly precipi- tated and finally redissolved. No gas is produced from any medium. The paper was illustrated by fifty lan- tern slides showing the location of the bac- teria in the tissues and illustrating the morphology and cultural characters of the organism.