摘要:

A study of morphologic character in relation to field resistance to black stem rust of wheat (Puccinia graminis tritici, Erikss. & Henn) was made on the cross Vernal (Triticum dicoccum, Schubl.) × Marquis (T.vulgare, Host.). Fifteen morphologic characters were used including spike form, spike compactness, stem hollowness, rachis articulation, rachis width, spikelet adherence, glume adherence, keel sharpness and seed character, all of which are of species differentiating importance. A random group of 276 F2plants showed no strong or moderately strong correlations between rust reaction and other characters: the most significant correlation coefficients ranged from.13 to.27. Between any two morphologic characters no strong relationships were found, the highest correlation coefficient obtained being.37. In the entire F2population of 21,480 plants there were 232vulgare-like hybrids showing the high rust resistance of Vernal, although Marquis had a fairly uniform infection of moderate severity. All of these hybrids proved, upon laboratory examination, to be ofvulgareor near-vulgaretype in nearly all characters especially the economically important characters spike form, rachis articulation, spikelet adherence and glume adherence. This study, therefore, demonstrates that high rust resistance can be transferred fromdicoccumto avulgare-type wheat without great difficulty. It is concluded that the attainment of desirable combinations of emmer rust resistance with important morphologic characters ofvulgaredepends primarily upon having a population of many thousands of individuals from which to select.

ISSN:1923-4287    

DOI:10.1139/cjr30-024

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

Specimens of three species of fresh-water entomostracans—Daphnia pulex,Daphnia magnaandCypris reticulate—were each exposed to sunlight which had passed through filters which transmitted different regions of the solar spectrum. One filter ("Total") transmitted both visible and ultra-violet radiation, a second ("Novial") transmitted the visible only and a third ("U.V.") transmitted only the ultra-violet. By prolonged exposure the animals were killed under the Total and U.V. filters, while under the Novial they lived indefinitely. The chief point of interest lies in the comparison of the results obtained with these entomostracans which live in shallow pools with the results of previous experiments (2) on three marine entomostracans which remain at a considerable depth in the sea when the illumination is at all intense; the comparison shows that the former have a far greater resistance to the lethal effects of the sun's ultraviolet radiation. Developing embryos of the squid,Loligo pealii, were experimented upon in a similar manner; these embryos, which are enclosed in a gelatinous matrix attached to large algae in the intertidal zone, and, at low tide, are exposed to full sunlight, were extremely resistant to ultra-violet radiation.

ISSN:1923-4287    

DOI:10.1139/cjr30-025

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

The rate of diffusion of water vapor through wood has been studied through a comparison of the time taken for samples of various thickness to become saturated. This process is, in a sense, the converse of natural drying, and for comparative purposes is more amenable to careful control of pressure and temperature. Continuous measurements of the amount of adsorption were carried out by the use of a quartz spring balance completely enclosed in the apparatus at a constant vapor pressure.Comparative numerical values have been obtained of the rate of diffusion of water vapor through spruce (Picea canadensis) and pine (Pinus banxiana) in various directions, through heartwood and sapwood, and through samples of different lengths. The results are considered as evidence that the movement of water through wood at concentrations below the saturation point, takes place as vapor diffusion through the spaces of the wood structure due to the pressure gradient consequent on the difference of moisture content.

ISSN:1923-4287    

DOI:10.1139/cjr30-026

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

The investigation deals with the effect of low temperatures on the impact resistance of steel castings and forgings. Low, medium and high carbon steel castings and a few alloys of vanadium, nickel, and vanadium-nickel steel castings were examined. The metals were subjected to low temperatures, both before and after heat treatment. The temperatures for the tests varied from room temperatures to temperatures well below 0° F., so as to extend below the ordinary atmospheric range of temperatures found in northern climates.It was found that the impact resistances of the metals decreased for temperatures below the freezing point. For specimens, not heat treated, the impact resistance at − 40° F. may be only one-third to one-half of that at room temperature. Heat treatment increases the impact resistance at room temperatures and temperatures below the freezing point. The impact resistance at − 40° F. for the heat-treated metal compared favorably with the impact resistance of the untreated metal at room temperature, 68° F. Heat treatment may slightly lower the yield point and the ultimate tensile strength, but it increases the ductility and the impact resistance of the metal. By proper heat treatment of steel castings the impact resistance at − 40° F. may be brought over 300% higher than that of the untreated metal at that temperature.

ISSN:1923-4287    

DOI:10.1139/cjr30-027

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

The mechanism of the desulphurizing action of alkali cyanides on thiuram and xanthogen disulphides has been determined. The reaction is shown to take place in two steps, the intermediate products formed in the first step have been identified as disubstituted thiocarbamyl thiocyanates. These thiocyanates belong to a hitherto unknown series of organic sulphur compounds.Two methods for the preparation of the new thiocarbamyl thiocyanates are described.The mechanism of the formation of monoxanthogens by the action of acid chlorides on xanthates is shown to be similar to the formation of monosulphides by the action of cyanides on disulphides.The following new compounds are described: mixed thioanhydride of ethyl carbonic and isopropyl xanthic acids, C2H6OC (O)S.CS.OC3H7liquid; methyl phenyl thiocarbamyl isopropylxanthyl sulphide, C6H5(CH3)N.CS.S.CS.OC3H7, m.p. 42 °C.; ethylphenyl thiocarbamyl isopropylxanthyl sulphide, C6H5(C2H5)N.-CS.S.CS.OC3H7, m.p.41 °C.; methylphenyl thiocarbamyl thiocyanate C6H5(CH3)-N.CS.SCN m.p. 113.5–114 °C.; ethylphenyl thiocarbamyl thiocyanate, C6H5(C2H5)N.CS.SCN, m.p. 75.5 °C.; methylp-tolyl thiocarbamyl thiocyanatep-CH3C6H4(CH3)N.CS.SCN, m.p. 116.5 °C.: methylp-tolyl thiocarbamyl chloride,p-CH3C6H4(CH3)N.CS.Cl, m.p. 53–54 °C.; ethylo-tolyl thiocarbamyl chloride,o-CH3C6H4(C2H5)N.CS.Cl, m.p. 69 °C.; α1methylphenyl α11phenyl dithiobiuret, C6H5(CH3).N.C.S.NH.CS.NHC6H5, m.p. 123 °C.

ISSN:1923-4287    

DOI:10.1139/cjr30-028

出版商:NRC Research Press    

年代:1930

数据来源: NRC