Experiment Station Record, Volume 92, January-June, 1945 Page: 30
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30 EXPERIMENT STATION RECORD [Vol. 92
of wheat samples previously stored for 6, 18, and 30 mo. and then kept at 25 C.
(1) in contact with water and (2) in a moisture-saturated atmosphere for 40-hr.
periods. The lengths of the previous storage periods apparently had no significant
effect on the respiratory activities of the samples. Kernel size, however, had a
definite influence as shown by the amount of CO2 produced per unit weight of grain,
kernels of large average size giving a lower output than those of small average
III. The influence of atmospheric humidity mad mould infection on the carbon
dioxide output of zheat.-It was found that under the experimental conditions
wheat kept at 25 in atmospheres of relative humidities approximating 92-100
percent showed a continuously accelerating rate of CO2 output. This increased as
the relative humidity rose and became more pronounced in wheat from which the
germs had been removed than in undamaged grains. Where unlimited absorption of
water and germination of the grain was prevented, its CO2 production was due
almost entirely to the respiration of micro-organisms infecting it.
An improved arrangement for the measurement of carbon dioxide output of
respiring plant material by the electrical conductivity method, W. LEACH, D. R.
MoIR, and H. F. BATHO (Canad. Jour. Res., 22 (1944), No. 3, Sect. C, pp. 133142,
illus. 5).-A brief review (11 references) of applications of the electrical conductivity
method for estimating COa in respiration measurements is presented, and
an apparatus employing this method is described which was designed and constructed
for recording the respiratory XO2 output of plant material. The apparatus
comprises an oscillator, amplifier, and vacuum tube voltmeter working in conjunction
with a special type of absorption tube. A NaOH solution is used as the absorbing
agent. A simple set-up for automatic recording is also described.
The action of fumaric acid and maleic acid on the respiration of wheat roots,
H. LUNDEGARDH (Arkiv Bot., 31 (1944), No. 1, [Art. 31, Pp. 1-12, illus. 3).-Fumaric,
maleic, and pyruvic acids accelerated respiration (measured as O2 consumption)
in wheat roots. The Szent-Gy6rgyi hypothesis as to a catalytic function of the
C4-dicarboxylic acids is thus not supported. The acids in question are believed to
act as links in the "desmolysis" and to be consumed in the course of the process.
Observations on the effect of the metallic cations on the combustion of the acids
pointed to a regulating influence of the H-ion concentration-in the boundary between
the medium and the protoplasm. The combustion of the acids is believed to occur
in this layer. According to earlier investigations, its pH value is controlled by the
medium, viz, by its content of acids and metallic cations.
Light and the elongation of the mesocotyl in corn, L. H. FLINT. (La. State
Univ.). (Plant Physiol., 19 (1944), No. 3, pp. 537-543).-A series of experiments
with corn seedlings gave results interpreted as evidence that up to the time of leaf
blade emergence from the coleoptile, when mesocotyl elongation ceased irrespective
of light conditions, this elongation was retarded by blue but unaffected by red light.
The effect of environmental factors on the development of root hairs in
Phleum pratense and Sporobolus cryptandrus, R. G. H. CORMACK (Amer. Jour.
Bot., 31 (1944), No. 7, pp. 443-449, illus. 11).-The development of root hairs in
timothy grass proved similar to that previously found. by the author in cabbage
roots. In the roots of both plants differentiation into long and short cells occurred
in the meristem, but the capacity to form hairs was determined by the chemical
and physical changes occurring while the cells were elongating. Through the
gradual hardening of the cell wall longitudinal elongation is arrested, and because
of increasing pressure from within the wall is pushed out at its softest point,
invariably at or near the apical end of the cell. At this point elongation continues,
but in a new direction, and a long narrow hair results. Confirmatory tests with
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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/m1/43/: accessed April 25, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.