Annual report of the Board of Regents of the Smithsonian Institution . Abnormal Growth of an Unchilled Blueberry Plant. This plant became dormant in the autumn in a warm greenhouse, and not being chilled itcontinued its dormancy through spring and summer for a period of nine months. Thenthree of its stems began to die at the tips and, following this, growth began to take placefrom a single bud next below the dying tip on each stem, as shown in the the explanation of this abnormal activity see page 286. The photograph was takenOctober 12,1916. (Half natural size.) Smithsonian R
Annual report of the Board of Regents of the Smithsonian Institution . Abnormal Growth of an Unchilled Blueberry Plant. This plant became dormant in the autumn in a warm greenhouse, and not being chilled itcontinued its dormancy through spring and summer for a period of nine months. Thenthree of its stems began to die at the tips and, following this, growth began to take placefrom a single bud next below the dying tip on each stem, as shown in the the explanation of this abnormal activity see page 286. The photograph was takenOctober 12,1916. (Half natural size.) Smithsonian Report, 1919.—Coville. Plate Blueberry Leaf Exuding Sugar from Glands Interpreted as Osmotic-Pressure Safety Valves. This is a leaf of the high-bush blueberry, Vaccinium corymbosum. The photograph was taken May 19,1916, and is enlarged four diameters. The sugar-secreting glands, sometimescalledextrafloralnectaries,are situated in this plant on the back of the midrib and along the margins of theleaf, toward its drops of sugar solution have been wiped away from the glands on thel eft-hand margin and fromtwo glandson the midrib at the base of the second and fourth lateral veins above the sugar drop shownnear the middle of the picture. This exudation of sugar is interpreted as a means of relief from excessiveinternal pressure that might burst the cells of the plant or derange its physiological activities. COLD AND GROWTH OF PLANTS—COVILLE. 287 to expect that some of them will be found to accomplish this act inthe same way as our long-dormant greenhouse plants, by the weak-ening of their cell membranes. Thi
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