摘要:

SUMMARYExperiments have been carried out in the feeding of leafhoppers timragh membranes upon the juice of streak‐diseased maize plants after passage through various filters. Tests of these leafhoppers have shown that at apHof about 6 the virus passes through Chamberland LI, Berkefeld V and N niters, and less freely through Chamberland L3. Hie virus does not pass a Seitz E.K. filter dis

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1932.tb04301.x

出版商:Blackwell Publishing Ltd    

年代:1932

数据来源: WILEY

摘要:

SUMMARY1Further experiments are recorded in which the transmission of the recently described chlorotic disease of the hop was obtained by means of grafting and budding.2Transmission was obtained also by rubbing healthy leaves with macerated chlorotic tissue in such a way that.bruising of the lamina resulted.3In all the experiments described, with one exception (see above, p. 6), no symptoms of disease appeared until the year following that in which the inoculations were made.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1932.tb04302.x

出版商:Blackwell Publishing Ltd    

年代:1932

数据来源: WILEY

摘要:

SUMMARY1A serious disease of the Arum Lily(Richardia africana)is described, which causes the formation of large brown blotches on all parts of the aerial shoot system.2The cause of the disease isPhyllosticta Richardiaen.sp., a diagnosis of which is given.3Suggestions are made for the control of this disease both under glass and in the open.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1932.tb04303.x

出版商:Blackwell Publishing Ltd    

年代:1932

数据来源: WILEY

摘要:

SUMMARY1F. ScirpiLamb, et Fautr., previously described in its pseudopionnotal form, occurs in a mycelial form also; the cultural characters and method for conversion of the forms are given.2This variety is designatedpallensto distinguish it from a new variety designatednigrans.also occurring on cereals. The relationship of the two varieties is discussed.3Both varieties are associated with Fusarium disease in cereals, but are of little economic importance except when the varietypallensprevails on the ears of wheat and barley; infected grains used for seed, if still viable, give less vigorous plants and reduced yield of corn.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1932.tb04304.x

出版商:Blackwell Publishing Ltd    

年代:1932

数据来源: WILEY

摘要:

SUMMARYSome factors influencing the relative susceptibility of a wheat variety toTilletia cariesare recorded, and it is shown that infection varies with the spore load and with the date of sowing. The relative resistances of certain wheat varieties to bunt when contaminated separately with Little Joss bunt, their own bunt and bunt spores from other varieties are shown.Rye is susceptible toTilletia caries,but no infection is recorded onHordeum nudumandAvena nuda.Hybridization experiments between resistant and susceptible wheat varieties are described.The general trend of the experiments indicates that several of the so‐called immune or highly resistant varieties are susceptible when they are contaminated with bunt spores that are produced on those varieties. They indicate that the passage of the pathogen through the host increases the virulency of the disease. These phenomena are accounted for becauseTilletia cariesis not a single system of one identity but is composed of physiologic forms and the passage of the parasite through the host increases the virulency because this process leads to the selection of a particular form or forms well adapted to the environmental conditions. It is thought that resistance depends not on one single factor but on at least three, namely, the physiologic form of the parasite and its environment, and the strain of the host and its environmen

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1932.tb04305.x

出版商:Blackwell Publishing Ltd    

年代:1932

数据来源: WILEY

摘要:

SUMMARYA bacterium which resemblesPs. seminumCayley has been isolated from broad beans showing symptoms of chocolate spot in the field. The broad‐bean organism was found to be vigorously pathogenic to broad beans and to garden peas grown in the greenhouse. Two strains have both been passed five successive times through the cycle of isolation, inoculation into broad‐bean plants, the production of disease, and re‐isolation. Further study is necessary before a causal connection between this organism and the disease can be regarded as established.Temperatures between 20 and 30oC. and high humidity favour infection.Histological studies of stems which became diseased following puncture inoculations showed the presence of the broad‐bean organism within the vessels, in the intercellular spaces, and inside the cells of the invaded tissue. The tissues about the vessels and immediately under the epidermis seem to be invaded earlier than other tissues.Bacteriological characters of the broad‐bean organism are described.A non‐pathogenic strain was found which corresponded in bacteriological characters with the pathoge

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1932.tb04306.x

出版商:Blackwell Publishing Ltd    

年代:1932

数据来源: WILEY

摘要:

SUMMARYExperiments have been carried out on carbon dioxide production from sand cultures with peptone and glucose solution inoculated with various types of bacteria and protozoa, and with glucose and ammonium sulphate solutions of varying concentrations and C/N ratio. The following results were obtained:1The presence of protozoa increases the carbon dioxide production especially in mixed bacterial cultsres2The increase of carbon dioxide production is greater in glucose solution than in peptone.3A further increase in the number of protozoa has an unfavourable effect on the carbon dioxide production.4The number of bacteria is smaller in the presence of protozoa than in their absence, but the bacterial efficiency is greater and more uniform.5The bacterial numbers and carbon dioxide production are definitely correlated in peptone, but in glucose to a less degree especially in the presence of protozoa.6The reduction of concentrations of glucose from 0–6 to 0–2 per cent. resulted in a greater percentage production of carbon dioxide.7With a lower concentration (0–2 per cent.) of glucose the presence of protozoa causes a greater increase in carbon dioxide production than in higher concentrations (0–6 per cent.).8In the absence of protozoa increasing the C/N ratio had no or only a slight depressing effect on carbon dioxide production.9In the presence of protozoa increasing the C/N ratio is followed by a marked increase in carbon dioxide production.10In bacterial cultures a lessening of the C/N ratio below 10/1 results in a fluctuation of bacterial numbers.I am indebted to Sir John Russell for his kindness in giving me facilities to carry out the work in this Institution. The work was done in Mr D. Ward Cutler's department, and I take this opportunity of expressing my gratitude for his ever ready help and unfailing kindness. For the culture ofColpidiumI am greatly indebted to Miss Jane Meiklejohn of the same dep

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1932.tb04307.x

出版商:Blackwell Publishing Ltd    

年代:1932

数据来源: WILEY

摘要:

SUMMARY1A brief survey is made of the history and habits ofAtomaria linearisStephens, the Pigmy Mangold Beetle, and some new observations recorded.2The egg and the external structure of the larva are described for the first time.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1932.tb04308.x

出版商:Blackwell Publishing Ltd    

年代:1932

数据来源: WILEY

摘要:

SUMMARY1The initial product of the interaction ol cupric sulphate and calcium hydroxide solutions, at ordinary temperatures, is the 4CuO. S03basic sulphate.2With amounts of calcium hydroxide in excess of 0–75 equivalent, the 4CuO. S03salt is slowly decomposed with elimination of the sulphate radicle and the formation of a blue hydrated cupric oxide or cupric hydroxide, a product called, for convenience, the hydroxide.3The cupric hydroxide formed retains, by adsorption, part of the sulphate radicle. Direct evidence by analysis of the precipitate, which might be considered to indicate the formation of a basic copper‐calcium complex, is therefore unreliable.4In the analogous interaction of calcium hydroxide with cupric chloride, the formation of cupric hydroxide in the presence of amounts of calcium hydroxide in excess of 0–75 equivalent, is indicated by the dehydration of the precipitate to form nigger brown hydrated cupric oxide, and by the definite point of inflection on the hydrogen‐ion concentration curve which corresponds to equimolecular amounts of calcium hydroxide and cupric chloride.5The hydrogen‐ion concentration curve for the cupric sulphate‐calcium hydroxide reaction shows that permanent alkalinity is not‐reached until equimolecular amounts of calcium hydroxide have been added.6The cupric hydroxide, formed from the 4CuO.SO3basic sulphate by the action of calcium hydroxide, is stabilised by adsorbed sulphate ions. If the adsorbed sulphate and excess calcium hydroxide be removed by continued washing with carbon dioxide‐free water, the Bordeaux mixture precipitate undergoes dehydration to form the nigger brown hydrated cupric oxide.7Dehydration of the Bordeaux mixture precipitate when sprayed upon foliage, is therefore prevented by some chemical or physical change of the precipitate which occurs on drying.8Dehydration is not prevented by physical changes which occur on drying.9Carbon dioxide is a factor in the process whereby dehydration is prevented.10It is suggested that the formationin situof the protective copper‐containing deposit by the action, primarily, of carbon dioxide, accounts for the excellent adhesive properties of the Bordeaux mixture precipitate; that inertness towards the chemical changes which occur after spraying may be the cause of failure of some Bordeaux substitutes; that these changes may profoundly affect the value of sedimentation tests as criteria for the fungicidal efficiency of various

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1932.tb04309.x

出版商:Blackwell Publishing Ltd    

年代:1932

数据来源: WILEY

摘要:

Die Tierischen Schdälinge des Ackerbaues.Von SofieEostrupund MathiasThomsenAn Introduction to the Literature of Vertebrate Zoology based chiefly on the titles in the Blacker Library of Zoology, the Emma Shearer Wood Library of Ornithology, the Bibliotheca Osleriana and other Libraries of McGill University, Montreal.Compiled and edited by CaseyA. Wood, M.D., LL.D.Economic Biology for Students of Social Science. Part II, Animal and Vegetable Products.By PhilippaC. Esdaeue, D.SC

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1932.tb04310.x

出版商:Blackwell Publishing Ltd    

年代:1932

数据来源: WILEY