摘要:

SUMMARYThe black lines ofPolyporus squamosushave been found in the wood of elms. Isolations were made from these lines and an account of the development ofP. squamosusin artificial culture is given. Particular mention is made of the formation of black plates, or lines as they appear in section, in culture media and of the appearance of abnormal fructifications. Pure cultures of the fungus on sterilized wood blocks have produced black lines in the wood, similar to those occurring in nature.From a consideration of the structure and formation of the black plates, the suggestion is made that they form the limiting layer or rind of sclerotium‐like bodies buried in the attacked wood.A review is given of sclerotium formation and structure in several species ofPolyporus,and analogies are made between these sclerotia and the sclerotium‐like body ofP. squamosus.It is decided to distinguish theP. squamosusbody from these sclerotia by naming it a pseudo‐sclerotium, on the criteria previously advanced forArmillaria mell

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1936.tb06103.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

摘要:

SUMMARY1An account is given of the occurrence and distribution ofFomes fraxineus.2The appearance of the fungus in culture and details of the hyphae are described.3Fruit bodies, in the form of pore surfaces bearing basidiospores on typical basidia, were obtained. Monosporous cultures derived from these spores were found to be heterothallic, sex appearing to be determined by two factors.4The formation of fructifications is favoured by certain media but does not seem to be influenced by light, temperature or moisture.5The optimum temperature for growth is 26oC, and the optimum hydrogen‐ion concentration ispH. 6.6The fungus was found to be moderately resistant to zinc chloride, sodium fluoride and coal‐tar creosote.7A list of enzymes found to be present is given and some preliminary experiments on the effect of nitrogen on the activity of diastase and oxidase produced by the fungus are outlined.8The growth of the fungus on ashwood and some other woods was investigated. The fungus grows well on ash, beech and elm and is able to attack oak, Scot's pine, Sitka spruce andRobinia pseudacacia.Ann Biol xxIII 32A description of the hyphae in the cells of the wood and their effect upon the walls is gi

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1936.tb06104.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

摘要:

SUMMARYIt is shown that top necrosis can be produced in different potato varieties by a number of viruses. The reactions of these viruses on a large number of commercial varieties are given, together with certain of their properties and methods by which they can be transmitted. By grafting and needle inoculating infected potatoes to the four varieties Epicure, Arran Victory, President and Up‐to‐Date, and noting the type of necrotic disease produced on these differential hosts, it has been found possible to distinguish with a fair degree of accuracy between six viruses. The necrotic reactions of these varieties are given below.The writer has great pleasure in expressing his gratitude to Dr D. R,. Salaman for permission to make use of the virus material, and for many valuable suggesti

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1936.tb06105.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

摘要:

SUMMARYA number of spraying experiments showed that the virus cannot enter a plant unless some of the cells are injured. It is not essential that such injury should be brought about in the presence of the virus. The chances of infection fall off rapidly in the first few minutes after injury, but infection occurs occasionally as long as half an hour after the cell is damaged.Inoculations by micropipette into single cells of the host plant yielded only about one‐tenth of the expected number of infections. This suggests differences in the susceptibility of the cells to virus attac

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1936.tb06106.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

摘要:

SUMMARYAlthough intracellular inclusion bodies may occur in every cell over large areas of the epidermis, they have not been found in the guard cells of the stomata. No protoplasmic connexions could be shown to exist between the guard cells and the surrounding tissues. These findings suggest that, owing to the absence of plasmodesms, the virus is unable to reach the guard cells. Support is lent to the view that, when the virus moves in the ground tissue of the host, it is carried from cell to cell along the protoplasmic bridges.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1936.tb06107.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

摘要:

SUMMARY1The interpretation of lesion counts in terms of the relative concentration of active virus units is discussed in its bearing on our results.2The effect ofpH. value on the activity of the virus of tomato spotted wilt has been examined with the following results:(a). Activity‐time curves at constantpH. value show that in some instances in the absence of oxygen and at 0oC. suspensions of the virus buffered atpH 7 maintain their activity without loss for at least 11 hours. In other instances a fall in activity sets in after about 6 hours and in others even sooner, but in general suspensions remain at constant activity under these conditions for 6 hours or more. Time‐activity curves atpF values of 5‐2, 6‐0, 8‐7 and 9‐2 are also recorded.(b). An activity‐pH curve for the virus (in the absence of free oxygen and at 0oC.) has been constructed. It has been found that the virus is rapidly inactivated at and below apH value of 5 and above apH. value of about 10. There is no significant difference in activity over thepH range 6–8‐9 for a half‐hour or 5‐hour contact.3A study of the effect ofpH. value on the activity of ordinary tobacco mosaic virus has revealed the following relationships:(a). Activity‐time curves at constant pH value show that:(i). Suspensions of this virus buffered atpH. 7 do not change in activity over a period of at least 24 hours at room temperature (ca.20oC).(ii). Suspensions atpH. about 9 undergo a rapid fall in activity, but eventually reach a steady state and then remain constant. If the suspensions (atpH 9) are adjusted topH 7 shortly after preparation a marked reactivation takes place, the difference in activity of the adjusted (topH 7) and unadjusted suspensions getting progressively smaller with time. It is concluded that portion of the virus was completely and irreversibly inactivated, that the amount so inactivated increased with time, that a small portion was reversibly inactivated (i.e. was reactivated when suspensions were adjusted topH. 7), and that the portion capable of reactivation decreased progressively with time.(iii). Suspensions atpH 2 when inoculated at thispH. value cause significantly fewer lesions than the corresponding control inocula, whereas the activity of suspensions held atpH 2 for various times and adjusted topH 7 before inoculation is not significantly different from that of the controls atpH. 7. The differences are discussed and in part at least ascribed to an effect on the host plants.(b). Two activity‐pH curves have been constructed for tobacco mosaic virus. One, when the suspensions were adjusted topH 7 after 12‐hour contact at the testpH values and another when the suspensions were inoculated at the testpH. value. It is concluded from these tests that the virus undergoes inactivation abovepH 8‐2 and belowpH 2. The extent of this inactivation varies with thepH. value and is complete atpH. 11 and 0–5. There is no significant difference in the activity of the virus over thepH. range 2–8 in the adjusted suspensions and over thepH. range 6–8 for the unadjusted suspensions. Differences between the apparent activity of adjusted and unadjusted suspensions at lowpH.values are recorded and their probable causes discussed. BetweenpH. values of 2 and 5 these differences are relatively small and are probably due in the main to an effect of the acidity of the inoculum on the host plant.4The bearing of these results on other problems connected with plant viruses is briefly discussed, and it is pointed out that in the case of tobacco mosaic virus at any rate they are strong evi

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1936.tb06108.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

摘要:

SUMMARYThe species of coliform bacterium predominant on fresh grass was found to be a capsulated type growing well at 30oC. but unable to grow at 37oC. For this reason it will not be detected by the presumptive test in bile salt‐lactose broth at 37oC. The nameBacillus (Aerebacter) aerogenes graminisis proposed for this species.It is possible that conforms of the above type contribute to a small extent to the initial fermentation of the silage. Those coliforms giving the presumptive test at 37oC. were found in such small numbers in the silage investigated that their influence was concluded to be negligible.This work forms part of some research carried out under grant from the Research Council of Imperial Chemical Industries, Ltd., to whom the authors wish to make due acknowledgement. Valuable help was also received from Dr S. J. Watson, who supplied samples of grass and silag

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1936.tb06109.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

摘要:

SUMMARYSamples of 152 strains of lacto bacilli isolated from six different types of grass silage, which had been subjected to various treatments at the time of ensiling, and five strains isolated from other sources for comparative purposes, were tested by their reactions in litmus milk, yeast extract litmus milk, dextrose litmus milk, yeast extract dextrose litmus milk and in various carbohydrate broths. The metabolic products formed from dextrose by nineteen selected strains were identified and estimated.The evidence obtained in this way pointed to the conclusion that the majority of lactobacilli in grass silage are strains ofStreptobacterium plantarum,characterized by comparative inactivity in ntmns milk, bat markedly stimulated by addition of yeast extract. They produce from dextrose mainly lactic acid (usually the inactive form) with a small quantity of acetic acid. A strain was encountered which also produced alcohol and butyric acid, but the numbers of this type in silage was negligible. Considerable differences were found in the ability of the various strains to ferment carbohydrates.Of the five strains isolated from dairy products three woe of theStreptobacterium plantarumtype and two were of a kind which rapidly clotted litmus milk and exhibited reactions corresponding to the true milk strains.The authors wish to record their thanks to the Research Council of Imperial Chemical Industries, Ltd., for a grant which rendered this work possible, to Dr S. J. Watson for supplying samples of grass and silage, and to Dr J. 6. Davis for valuable suggestions.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1936.tb06110.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

摘要:

SUMMARY“European foul brood” has been initiated in healthy nuclei by feeding either the young larvae directly or the bees naturally infected material. The disease thus produced varied from a mild transient infection to a serious form depending upon whether the inoculation had been made early or late in the brood‐rearing season. In one experiment in which a nucleus very strong in bees was employed no disease resulted.“European foul brood” has also been induced in healthy nuclei by suspending in them combs containing artificially infected larvae in which disease had been produced by feeding them pure cultures ofStreptococcus apisorBacillus alveiand then starving them under conditions favouring the growth of the bacteria. The susceptibility of nuclei to infection by this means seems to be governed by approximately the same conditions as pertain to inoculations made with material obtained from natural sources. The disease thus induced ultimately becomes a mixed bacterial infection of the brood.Attempts to cause disease by feeding the bees or larvae (without starving them) relatively large numbers ofS. apisorB. alveiorganisms have as yet proved unsuccessful. Whether this is due to the fact that these bacteria become attenuated with respect to virulence by culturing them on artificial media, or that decomposing brood acts as a vehicle and that the relative inoculum is greater by this method, remains to be determined.The failure to produce “European foul brood” by feeding sterile Pasteur‐Chamberland L 2 or L 3 filtrates prepared from naturally infected larvae to the bees or larvae of healthy nuclei, either with or without bacteria, may be taken as strong evidence in support of the view that a filterable virus is in no way implicated as an etiological agent in this type of disease. This conclusion is strengthened by the success which has attended the use of pure cultures of the bacteria associated with this disease employing the “starved larvae” technique described.The introduction of queen bees from nuclei affected with “European foul brood” into healthy queenless nuclei has not caused any transmission of the disease under the conditions of the experiments.Two species ofS. apisMaassen have been isolated from affected larvae taken from several different cases of “European foul brood”; one of these hydrolyses both casein and gelatine, the other does not. In other respects these species appear to be identical.The etiology of so‐called “European foul brood” is discussed in detail, and it is suggested from the evidence submitted in this and other papers that it may not be a single disease with one well‐defined etiological agent, as is American foul brood, but is, perhaps, a non‐specific mixed bacterial infection of the brood of bees, especially of the brood of weak colonies. This conclusion must be regarded as temporary pending further investigation.My thanks are due to Mr D. M. T. Morland and to Mr A. Rolt, whose generous advice and assistance in connexion with the apiary work greatly facilitated the carr

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1936.tb06111.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

摘要:

SUMMARY1Adelges cooleyiis a pest of Sitka spruce, the primary host, and Douglas fir, the secondary host, on the latter of which it has been known in Britain since 1913.2Hitherto its life cycle in Britain has been regarded as incomplete because of the non‐viability of generation I (sexuales) on Sitka spruce and consequent absence of the subsequent generation II (fundatrix vera) and generation III (gallicolae).3Both of these generations have been discovered for the first time in Britain and their development followed.4The investigation began with the finding of the dead galls ofA. cooleyion Sitka spruce at Glen Tress in February 1935. Subsequently, dead galls were also found at Stobs, Melrose, Dreghorn and Murthly. At Melrose they were found on a new secondary host, the white spruce,Picea alba.Later the fundatrix vera of generation I was found.5The growth of the galls was followed on cut twigs in the laboratory and on growing shoots in the field; galls of the current season were found at Glen Tress, Dreghorn and Murthly.6The winged gallicolae of generation II were observed migrating to Douglas fir, where they settled and oviposited. From the eggs there hatched typical hibernating first‐instar nymphs (sistentes).7Generation III (colonici) was determined to be triple‐brooded, and this character has recently been noted inAdelges cooleyiin British Columbia.8The population of the sistentes on Douglas fir during any one winter was found to be composed of four categories, which hav* been designated.9The migration of generation IV (sexuparae) to Sitka spruce and white spruce was observed at Glen Tress and Melrose respectively. It was also verified in the laboratory.10Generation V (sexuales), for some cause or causes yet unknown, was practically exterminated during development. Only a few adults were observed. The solitary egg laid by the female of this generation was not discovered.11Further investigation is required concerning:(a). The causes of mortality of the sexuales.(b). The oviposition of the sexual female, and the sexually produced egg.(c). The extent of the distribution and establishment of the spruce generations in Britain.(d). The prospective status ofA. cooleyias a pest of Sitka spruce in Britain.12With regard to status, it would be unsafe, at the present juncture, to speculate, especially as the investigation has been conducted for only one year. I have, therefore, refrained from discussing possibilities of damage to the spruce host until more evidence is available.The writer is indebted to Mr R. Carrick, B.Sc, Research Student in the Department of Entomology, for the photograph of the winged gallicollae reproduced in PI. XXV, fig. 4. Part of the expenses incurred in conducting the investigation were met by a grant from the Earl of Moray Endowment of the University of Edinburgh, and it is a pleasure to acknowledge th

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1936.tb06112.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY