1. The particle diameter of bluetongue virus (sheep virulent and egg adapted virus) was determined by gradocol membrane filtration. 2. Details of the technique for clarifying infective emulsions by aluminium hydroxide adsorption and trypsin digestion are given. 3. The density of the egg adapted virus was calculated from data obtained from centrifugation in media of low and high specific gravity and was found to be 1.147.gm./cm.³ in strong cane sugar and 1.106 gm/cm.³ in serum albumin. 4. The particle diameter of the sheep virulent virus was determined approximately, and of the egg adapted virus accurately by centrifugation.

The work on insects in relation to the spread of orange tree quick decline has heen going on since 1945. During this period it was determined which insects are found commonly in southern California citrus groves and over 750 transmission tests were conducted in an attempt to discover the vector.

The description of an instrument to measure compressional stress-relaxation characteristics of textile materials at a constant compression, utilizing the sensitive response characteristics of a resistance-wire strain-gage cantilever weighbar, is given. It employs a deflection galvanom eter in conjunction with the strain gages in a D.C. Wheatstone bridge. Compression is applied instantaneously to the specimen and the semilog rate of stress relaxation is determined as a characteristic parameter of the behavior of the textile material.

The tensile and compressive properties of an unsaturated-polyester laminate with glass fabric as reinforcement and of several phenolic laminates with asbestos fabric, high-strength paper, rayon fabric, and cotton fabric (both high and low pressure) as reinforcements were determined at -70, 77, and 200 degrees F. | Izod impact and flexural tests on the same materials have been reported previously in NACA TN No. 1054.

In controlled experiments Jumbo Runner type peanuts were grown in soil which was known to produce good vine growth but poor quality fruit. By using the technique of separating the zone of fruit formation from that in which root growth occurred, a study was made of certain fruit characteristics as affected by supplying various salt solutions to the fruiting zone. The treatments were made to quartz sand which constituted the fruiting medium and the solutions were added in such a way that a continuous supply of the elements desired was available. By using proper treatments the specific effect of each of the anions and cations used was determined. Particular attention was given to the effect of calcium. The comparative effects of applying potassium to the rooting and fruiting zones, with and without calcium in the fruiting zones, were also determined. Fruit filling was evaluated by determining the total number of ovarian cavities in the fruit from a given treatment and by calculating the percentage of this number which contained well-developed kernels. Other fruit characteristics, such as disease, maturity, and percentage of 2-cavity size were also determined. In 1946 the effects of various treatments on gynophore development and disease incidence and stem composition were obtained. The results from these experiments may be summarized as follows: 1. Of the ions Ca, K, Mg, Cl, S04, KH2, and P04, calcium was found to be the only one which consistently increased fruit filling when applied to the fruiting zone. This was true regardless of the combination in which it was supplied. 2. In general, the addition of magnesium salts to the fruiting zone proved to be slightly beneficial to fruit filling. 3. The addition of potassium to the fruiting zone or rooting medium slightly depressed fruit filling in some instances in the absence of calcium in the fruiting zone. However, if a solution of calcium sulfate containing as little as 20 ppm calcium were supplied, no detrimental effect resulted from potash additions. This was true even when potassium was added at the rate of 320 ppm potassium. 4. The application of chloride, sulfate, and phosphate ions to the fruiting medium did not significantly affect fruit filling, although in 1943 phosphate tended to reduce the quality of fruit. 5. Chemical analyses of stems showed that calcium sulfate additions resulted in an increase in calcium and potassium and a decrease in nitrogen content.

Contains mathematical expressions derived for the stress distribution in a wood beam of rectangular cross section subjected to a concentrated load. The orthotropic nature of wood is taken into account in the derivation. The stress distributions are expressed in terms of infinite series. A method of reducing the infinite series to the sum of a finite series and a closed form is described. | The matematically determined distribution of horizontal shear in the vicinity of a concentrated load is compared with the actual distribution obtained by a test of Sitka spruce beam of rectangular cross section.

Experiments were conducted at State College, Pa., to determine the effects of several environmental factors on heading in the greenhouse of perennial ryegrass, orchard grass, timothy, meadow fescue, bromegrass, Canada bluegrass, and Kentucky bluegrass. The effects of various durations of supplementary light in addition to the normal winter day length were determined on all of the above species. The effects on heading of various intensities of supplementary light and of low temperature pretreatments were determined on perennial ryegrass, orchard grass, and timothy. Heading responses of orchard grass grown under favorable day lengths and with two levels of soil fertility were determined. None of the clones used of these perennial species headed under a normal winter day length of 10 hours. A few clones of the various species headed under a 12-hour day. The best heading was obtained under a 16-hour day, and almost equivalent heading occurred when the plants grown under 10 hours of daylight received 1 or 2 hours of supplementary light during the middle of the night. The dry weight of top growth of orchard grass, Canada bluegrass, Kentucky bluegrass, and a F1 hybrid of these latter two species was increased under a 16-hour day and also when the plants were grown under a 10-hour day with 1 or 2 hours of light during the night. It would appear from the results of these experiments that the length of the dark period rather than the length of the light period is a determining factor in the photoperiodic responses of these long-day species. Increasing the intensity of the supplementary light from 75 foot-candles to 150 and 300 foot-candles had little, if any, effect on increasing the number of clones of perennial ryegrass, orchard grass, or timothy that flowered. Low-temperature pretreatments of the established plants of these species before placing them under a long day did not generally increase the number of clones flowering or shorten the time required. With orchard grass, there was an indication that a longer growing period under short-day conditions aided in the initiation of heads when the plants were shifted to long days. Adequate fertility for the growth of orchard grass plants was an important factor in inducing heading. Pot-bound plants of this grass produced no heads under long days, whereas similar plants which had received a liberal top-dressing of fertilizer or had been transplanted to larger pots of new soil headed.

Growth rates were determined for the whole kernel and its component parts for dent and pop corn inbred lines and their reciprocal hybrids. Considering the whole kernel, both hybrids exhibited heterosis. A study of growth rates of their component parts, however, indicated heterosis was due to different causes in the two hybrids. This was explained on the basis of relative efficiency of endosperm and embryo as competitors for food materials. Heterosis appeared to be related to the action of specific genes rather than chromosomal dosage effects.

Involving five fertilizer treatments, frequent clippings of Kentucky bluegrass, Poa pratensis L., mixed with white clover, Trifolium repens L., from 25 experimental plots throughout a period of 7 months were quantitatively collected and analyzed. In addition to complete feed analysis, calcium, phosphorus, magnesium, and potassium were determined. Increases in total protein, energy, and dry matter were evident in accord with the fertilizer treatment. It was found that high yield was associated with high quality (feeding value) except that the potassium tended to replace calcium and magnesium. A midseason application of nitrogen (ammonium nitrate) exerted a definite, favorable effect to increase the nutritive value of the harvested forage. The crude fiber content did not vary appreciably in any of the fertilizer treatments over a period of 5 months.

A pot experiment was conducted with virgin Lakeland fine sand and Florida 167 variety of oats. Thirteen treatments were made, replicated four times, with varying lime, phosphate, and zinc applications to the soil. Average weights of two cuttings of the oats, as well as zinc and phosphorus contents, were determined. The zinc content of the plants decreased to an almost constant value with increasing rates of application of phosphate, while the phosphorus content increased regularly in diret ratio to that applied. Higher rates of application of phosphate resulted in significant increases in plant weights at the second cutting. The zinc content decreased with increasing rates of lime application but increase regularly with increasing zinc applications.