Experiment Station Record, Volume 92, January-June, 1945 Page: 29
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1945 AGRICULTURAL BOTANY 29
existence of a discrepancy between the osmotic pressure of cell sap measured
plasmolytically v. cryoscopically was verified; this discrepancy varied among several
lots of beets differing in age, developmental stage, and conditions of growth.
Changes in volume, adhesion of the protoplasm to the cell wall, and systematic
errors in method were in no case sufficient to explain the discrepancies found in
certain plants. Tests involving plasmolysis of cells in their own sap, equilibrium
between living and dead tissue cylinders and sucrose solutions, and freezing point
determinations of living and dead tissue as well as of expressed sap substantiated
the reality of the discrepancy between the two methods and helped to explain its
cause. It is suggested that these discrepancies are related to contamination of
expressed sap by liquid held by and expressed from the protoplasm, the discrepancy
may be positive or negative depending on whether the contamination is less or more
concentrated than the vacuolar sap, the nature of the contaminating protoplasmic
sap depends on the state of hydration of the cytoplasm, and where the discrepancy
is positive (protoplasmic less concentrated than vacuolar sap) the cells may be
in a cold-hardy condition. Evidence for the "secretion" of water by the living
protoplasm is questioned. There are 38 references.
Cryoscopy of small amounts of expressed tissue sap, H. B. CURRIER (Plant
Physiol., 19 (1944), No. 3, pp. 544-550, illus. 4).--During an investigation of water
relations in root cells of red beet, it became necessary to devise a method whereby
osmotic pressure values of 0.5-1 cc. of sap, expressed from small blocks of tissue,
could be obtained. The cryoscopic apparatus and procedure here illustrated and
described are simple and are said to permit up to six determinations per hour.
Bibliography of references to the literature on the minor elements and their
relation to plant and animal nutrition, L. G. WILLIS (New York: Chilean Nitrate
Ed. Bur., Inc., 1943, 3. ed., Sup. 4, pp. 92+; 1944, 3. ed., Sup. 5, pp. 96+).-Fourth
and fifth supplements to the third edition (E. S. R., 87, p. 491).
Effects of limiting ions on the absorption of nutrients by wheat, D. ROSEi and
A. G. MCCALLA (Canad. Jour. Res., 22 (1944), No. 3, Sect. C, pp. 87-104, illus. 4).Wheat
grown in culture solutions limited in 1 or 2 nutrients was analyzed for N, P,
S, K, Ca, and Mg. Limiting the N reduced plant size and the weight of all nutrients
absorbed except P; percentages of P and S increased. Limiting Ca had the
least effect on nutrient uptake. Limiting K had no effect on percentage of anions
but decreased the total weight absorbed. The percentages of Ca and Mg were
increased, while the weight of Ca was increased in one series. Though limiting
N and Ca had marked effects on the ratios of various ions absorbed, the total
anion : cation ratio was not affected; limiting K, however, caused an increase in
Studies on the metabolism of cereal grains, I-III, W. LEACH (Canad. Jour.
Res., 20 (1942), No. 3, Sect. C, pp. 160-168, illus. 6; 21 (1943), No. 10, Sect. C, pp.
289-296, illus. 6; 22 (1944), No. 4, Sect. C, pp. 150-161, ills. 5).-The following
papers are included:
I. The output of carbon dioxide by wheat grains during absorption of water and
germination.-The respiratory course during the early stages of germination is
recorded for a number of varieties of bread and durum wheats. Germination was
marked by three consecutive respiratory stages, viz, (1) a slow rate of acceleration
in C02 output, (2) an increased followed by a decreasing rate, add (3) a final
uniform and relatively high rate. Under the conditions used, the water absorption
rate apparently did not affect these respiratory stages. The infection of germinating
grains by fungi reduced their respiration. Possible physiological explanations of
the respiratory stages are discussed.
II. The effect of age and kernel size on the course of respiration of wheat during
early germination stages.-The author reports on hourly records of CO2 outputs
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U.S. Department of Agriculture. Agricultural Research Administration. Office of Experiment Stations. Experiment Station Record, Volume 92, January-June, 1945, book, 1947; Washington D.C.. (digital.library.unt.edu/ark:/67531/metadc5064/m1/42/: accessed March 24, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.