摘要:

not available

ISSN:1923-4287    

DOI:10.1139/cjr34-079

出版商:NRC Research Press    

年代:1934

数据来源: NRC

摘要:

The radiation field due to a circular disc oscillating with uniform amplitude in a closely fitting circular aperture surrounded by an infinite rigid flange has been studied in detail, the velocity potential being expressed as an infinite integral involving cylindrical co-ordinates. The procedure adopted may be used to study the effect of viscosity on the characteristics of the radiation field. While having little effect on the field in the neighborhood of an oscillator generating waves in water, the viscosity has a marked effect on the range of distant transmission, which in consequence is appreciably affected by temperature. Of considerable practical importance is the existence of an optimum wave-length for constant output and a given distance of transmission. By means of a simple chart, it is possible to determine the optimum wave-length for a given transmitter when the level of reception for a given range is stated.

ISSN:1923-4287    

DOI:10.1139/cjr34-080

出版商:NRC Research Press    

年代:1934

数据来源: NRC

摘要:

This paper is a continuation of Bubb's (1) theoretical work which relates the energies and momenta of cathode rays to the properties of X-ray photons produced by them. Bubb's results are used to determine a scattering function for the cathode rays in a target in terms of the intensities of X-rays of minimum wave-length emergent from the target at various angles to the incident cathode-ray stream. It is shown that the self-consistency of Bubb's results can be tested by measurements of the intensities of two components of these X-rays polarized in mutually perpendicular planes. Mention is made of an experiment now in progress designed to test Bubb's theory by an absolute measurement using a gaseous instead of a solid target.

ISSN:1923-4287    

DOI:10.1139/cjr34-081

出版商:NRC Research Press    

年代:1934

数据来源: NRC

摘要:

Oscillograms showing unusually low layer reflections and exceptionally strong multiple reflections from theFlayer, and oscillograms of the usual conditions for February, March and April, are presented. Some automatic continuous records of the heights of the reflecting layers are also shown.The main features of the new design and technique, which were important factors in the elimination of all extraneous results, are clearly pointed out.

ISSN:1923-4287    

DOI:10.1139/cjr34-082

出版商:NRC Research Press    

年代:1934

数据来源: NRC

摘要:

In continuation of the authors' earlier work on substances having a carbonyl bridge, it has been found that tetraphenylcyclopentadienone can be used as one of the components in the diene synthesis. Products are described resulting from the addition of maleic anhydride, maleic, fumaric, and acetylene dicarboxylic esters, and benzoyl phenylacetylene. In some instances the primary addition products containing a carbonyl bridge could be isolated. Tetraphenylbenzene derivatives result from secondary reactions. Benzalacetophenone, dibenzoyl-ethylene and diphenylketene did not add to tetraphenylcyclopentadienone.In the previously described reaction between maleic anhydride and anhydroacetonebenzil, certain intermediates have been isolated, confirming the mechanism suggested to account for the formation of a dianhydride.

ISSN:1923-4287    

DOI:10.1139/cjr34-083

出版商:NRC Research Press    

年代:1934

数据来源: NRC

摘要:

The homogeneous first order gaseous decomposition of paraldehyde to acetaldehyde has been studied at temperatures from 230 to 254 °C. up to pressures at which the liquid phase makes its appearance,i.e., 12 atm. at 230° and 18 atm. at 254 °C. Over-all velocity constants for the homogeneous reaction in the heterogeneous liquid-vapor system have been determined from these pressures up to the critical point. The data confirm results already published. It is found that in the purely gaseous system increase of pressure tends to diminish the reaction velocity. That the specific reaction velocity in the liquid phase is greater than that in the vapor phase is shown by the fact that the velocity constants of the heterogeneous systems increase progressively with the liquid-vapor ratio. Extrapolation to 100% of liquid gives velocity constants about five times as great as those characteristic of the vapor phase. Peculiarities in the behavior of the system at the critical point and preliminary measurements of the velocity of the trimolecular reverse reaction are described.

ISSN:1923-4287    

DOI:10.1139/cjr34-084

出版商:NRC Research Press    

年代:1934

数据来源: NRC

摘要:

Evidence is submitted that some conidia of the black knot fungus,Dibotryon morbosum(Sch.) T. and S., are capable of overwintering in a viable condition onPrunus domestica.D.morbosumhas also been isolated on numerous occasions during the winter from definite chlamydospores on buds and bark ofP.domestica. Pure cultures ofD.morbosumproduced chlamydospores only when grown in close proximity to certain other organisms, or when certain chemicals were introduced into the Petri dishes. Chlamydospore formation was also induced on twigs ofP.domesticawhen conidia ofD.morbosumgerminated in intimate association with a strain of bacteria originally isolated from the same host.Cladosporium carpophilumwas isolated in several instances from chlamydospores on the bark ofPrunus persica. This organism also produced chlamydospores both on culture media and on peach twigs. A histological study revealed the presence of two types of twig lesion. Early infections produced primary lesions during the summer, and secondary lesions during the following winter as a result of the migration of the mycelium beyond the barriers of periderm delimiting the primary lesions. Late infections, on the other hand, rarely induced periderm formation and did not produce secondary lesions during the winter.Taphrina deformanswas isolated during the winter from the surface of buds onP.persica. Proof is submitted that spores ofT.deformanscan remain viable throughout the winter on twigs of the above-mentioned host. Other fungi, presumably saprophytes, representing the generaConiothyrium,Cladosporium,Hormodendrum,Fumagoand a fungus impossible to identify because it produced chlamydospores only, all developed from chlamydospores occurring on various hosts. The latter fungi all produced chlamydospores in culture. The evidence obtained indicates the probability that many more fungi over-winter as chlamydospores than have been reported to do so. Certain misapplications of the term chlamydospore in the various groups of fungi are dealt with. Owing to their unsatisfactory mycological status the importance of chlamydospores has hitherto been incompletely appreciated. The results of these investigations emphasize the importance of the application of a dormant spray on fruit trees.

ISSN:1923-4287    

DOI:10.1139/cjr34-085

出版商:NRC Research Press    

年代:1934

数据来源: NRC

摘要:

Considerable interest has been aroused over the possible relationships existing between the presence of awns and the grain yield of wheat. The general consensus of opinion is that awned varieties tend to outyield awnletted or awnless varieties. A number of investigations with barley and wheat have shown that the awns play an important role in transpiration, and that their removal results in reduced yields. Genetic studies dealing with the relation between awns and grain yield of wheat have given contradictory evidence. Certain workers have reported positive, others negative, and still others no relationship, existing between the presence of awns and grain yield.In the present investigation, the problem was studied with a number ofF3lines of Reward × Caesium, and also with a number of awned and awnletted strains of Marquillo × Marquis-Kanred. In neither case were any significant relationships found to exist between awns and grain yield. The apparently contradictory results obtained by the different investigators suggest that the relation between the two characters differs, depending both upon the material used and the environmental conditions under which it is grown.

ISSN:1923-4287    

DOI:10.1139/cjr34-086

出版商:NRC Research Press    

年代:1934

数据来源: NRC

摘要:

The history and the present state of the classification of the Gramineae are briefly reviewed and a number of the different characteristics on which phylogenetic systems have been based are considered. The subjects of chromosome morphology and the application of idiograms and karyotypes to taxonomic studies are discussed. Avdulov's recently reported findings on the phylogeny of the grasses are summarized and compared with the results of other workers and those obtained in the present investigation. Three species of bamboos were studied for the first time and evidence secured to indicate that the basic number of the tribe is probably not 12 as has been elsewhere reported. In the Festuceae the chromosome number ofPhragmites communisTrin. was definitely ascertained, confirming Avdulov's supposition that the basic number for the genus is 12. The other three species investigated agreed with the arrangement as proposed by Avdulov. The tribe Chlorideae, with the exception of the genusBeckmannia, has been reported to be almost entirely Panicoid with respect to chromosome morphology. This was confirmed in the four species examined. Avdulov's rearrangement of the tribe Hordeae was somewhat altered and a confusion m the nomenclature of the genusLepturuswas corrected. An anomalous situation was cleared up in the tribe Agrostideae by the establishment of the chromosome number ofSporobolus tennuissinusKuntz as 40. The specimen ofAnthoxanthum odoratumL. (tribe Phalarideae) examined provided a very interesting example of secondary splitting in somatic chromosomes. One species was examined in the tribe Melinideae and six in the tribe Paniceae. In the latter tribe no difference could be detected between the several subdivisions of the genusPanicum. The same condition held for the large genusAndropogonin the tribe Andropogoneae. In the tribe Maydeae the chromosome number ofTripsacum dactyloidesL. was found to be 9, and the suggestion was made that it may be a link, along with the genusCoix, between the Andropogoneae and the Maydeae. The other four species examined all had a basic number of 10.

ISSN:1923-4287    

DOI:10.1139/cjr34-087

出版商:NRC Research Press    

年代:1934

数据来源: NRC

摘要:

Ophiobolus halimusDiehl and Mounce n. sp. is reported onZostera marinaL. from St. Andrews, N.B. It was collected on rhizomes and fertile shoots, and developed in leaves kept in sea water in the laboratory. The fungus is described and illustrated and it is compared with related species.

ISSN:1923-4287    

DOI:10.1139/cjr34-088

出版商:NRC Research Press    

年代:1934

数据来源: NRC