bluuebunny/crossref_metadata_2025_split huggingface dataset:
ON THE LIFE‐HISTORY AND ECOLOGY OF LUMBRICILLUS LINEATUS MULL. (OLIGOCHAETA)
Authors: REYNOLDSON T. B. 
Published: February 2008

Summary

A survey of the natural and artificial habitats of Lumbricillus lineatus Mull, shows a wide range and toleration of diverse chemical conditions.
The bacteria beds are described in relation to the needs of the worm.
An account is given of the life‐history of the worm including breeding season, copulation, cocoon deposition, development and hatching. The latter is given in detail since it is believed to be new. It demonstrates a use of the eversible pharyngeal plate. Experiments show that the hatching worms increase in size with an increase in quantity of food available within the cocoon in the form of undeveloped ova.
A short account of the parasites and possible predators is given.
Experiment shows that the worms migrate from low temperatures to higher, a reaction observed in the beds during cold weather.
Temperatures below 6°C. affect adversely: (a) cocoon deposition, (b) rate of development, (c) hatching. The beds, in contrast to natural habitats, rarely fall below 6°C. Egg sterility is increased at a temperature of 20°C.
The bacteria beds form an environment for this worm which includes all the main features of its natural habitats. The higher temperature in winter, the protection from desiccation and birds, and the scarcity of natural predators allow excessive multiplication of the worm. Further, certain factors in the beds, probably the peculiar chemical conditions, prevent colonization by other similar worms so that competition with other Oligochaetes is at a minimum. Thus, by virtue of its great degree of physiological adaptability, this worm is able to thrive in the bacteria beds to an extent not found in any natural habitat.
NOTE ON THE LIMITATION OF INFECTION OF WHEAT BY ASCOSPORES OF OPHIOBOLUS GRAMINIS SAAC. A POSSIBLE EXPLANATION
Authors: PADWICK G. WATTS 
Published: February 2008

SUMMARY

Single spore cultures of O. graminis Sacc. produced ascospores on the host, confirming the conclusion of Davis (1925) that the fungus is homothallic.
Single spores removed from a Petri dish took several weeks to germinate, whereas the spores remaining in the dishes germinated within 24 hr.
It is suggested that a retardation of spore germination may have been due to dilution of some necessary chemical substance.
The significance of slow spore germination in relation to the results obtained by Garrett (1939) on infection of wheat seedlings by the ascospores of O. graminis is discussed.
AEROBIC DENITRIFICATION
Authors: Meiklejohn Jane 
Published: February 2008

DENITRIFICAITION is the reduction of nitrates to gaseous nitrogen, sometimes mixed with oxides of nitrogen: it is the only process which certainly causes a loss of nitrogen in nature, because the nitrogen gas escapes into the atmosphere. It is known that nitrite certainly, and probably hyponitrite, are formed as intermediates in the course of the reaction; it is obvious that nitrate (or nitrite) must be present if denitrification is to take place; and it is also known that a compound to act as a hydrogen donator is necessary for the process. Karlsen (1938) published a detailed study of the effect of pH and of iron on denitrification by Pseudomonas aeruginosa; and Elema (1932) and Elemaet al. (1934) studied the changes in oxidation‐reduction potential during denitrification by Micrococcus denitrificans. Elema's paper includes a set of equations which represents the most probable course of the reaction.Several details of the process remain obscure, among them being the effect of aeration. The generally accepted view is that denitrification is an essentially anaerobic process, and that it is diminished or stopped by the admission of air. This supposition is probably accepted mainly because it provides a neat teleological explanation for the fact of denitrification; oxygen is made available by the reduction of nitrate; so under anaerobic conditions the bacteria reduce the nitrate in order to supply themselves with oxygen. Under aerobic conditions they need not reduce nitrate to obtain oxygen, and it is therefore assumed that they do not reduce it. This supposition is based on very little experimental evidence; though Weissenberg (1902) described a strain of Pseudomonas aerugimsa, which grew on nitrite under aerobic conditions, but did not reduce it, while in anaerobic cultures the nitrite was all reduced with much gas production. There is no reason to suppose, however, that every denitrifying species is affected by aeration in the same way. Seiser & Walz (1925) found that nitrogen was lost from both aerobic and anaerobic cultures of Ps. putida. The effect of aeration on Ps. deniirofIuolescetrs was studied by Korochkina (1936), who remarks “a relatively high rH value does not exclude denitrification. Therefore it is very difficult to eliminate denitrification by means of increased aeration.”The experiments described in the present paper were mainly concerned with the effect of aeration on denitrification; they were performed with pure cultures of two denitrifying species in simple synthetic liquid media.
Field studies of potato‐root eelworm, Heterodera rostochiensis Wollenweber, 1938‐40
Authors: Miles H. W. , Henderson V. E. , Miles M. 
Published: February 2008

Field studies of potato crops under different soil and fertility conditions and exposed to attack by diverse concentrations of potato‐root eelworm led to the following conclusions:In the north‐western agricultural advisory province potato‐root eelworm is not a major cause of failure or partial failure of potato crops on land where the viable cyst concentration is low (under 10/10 c.c. of soil). On such land increased yields can be obtained by improving conditions for plant growth, widening the rotation and increasing the fertility of the soil.The production of satisfactory crops on land with a low eelworm population is likely to be accompanied by considerable increases in the numbers of root eelworms in the soil.Crops free from signs of ‘potato sickness’ or ‘potato‐root eelworm disease’ can be grown on land heavily infested with root eelworms (viable cyst concentration exceeding 25/10 c.c.), if no other adverse condition, such as unsuitable weather, lack of available food or incidence of fungus disease, affects the growth of the crop, but yields from heavily infested land are not likely to be more than moderate.The treatments used against eelworms in the trials described here did not give results commensurate with their cost.The practical difficulties of incorporating lethal substances with soil in the field are considerable, and this may have contributed to the disappointing results obtained.The study of the influence of host variety on cyst production suggests that varietal differences in the host plants may influence the numbers of cysts formed on the crop, but the evidence is not conclusive.
The depletion of starch from the sapwood of the ash (Fraxinus excelsior) and its relation to attack by powder‐post beetles (Lyctus spp.)
Authors: Henderson F. Y. 
Published: February 2008

The depletion of starch in the living sapwood of ash was examined as a possible means of rendering converted timber immune from attack by Lyctus (powder‐post beetle).Observations on disks of timber kept under controlled conditions showed that depletion is conditioned by access of oxygen; thus although in the standing tree depletion proceeds from without inwards, it can be induced in any part of the sapwood, and in any direction, by permitting access of oxygen, i.e. there is no polarity in depletion. The optimum temperature range for depletion in ash is from 31 to 36d̀ C.: above 45d̀ C. death of the cells may interrupt depletion.The presence of β‐indoly acetic acid does not influence rate of depletion. Reformation of the starch in the depleted wood in the presence of cane sugar could not be induced. The enzyme concerned in mobilization of the starch appears to be a labile one with an optimum in the neighbourhood of 40d̀ C. and to be produced during the active respiration of the cells, starch depletion ceasing when oxygen is withdrawn.In transversely cut disks the rate of respiration at 33d̀ C. ceases to be proportional to the volume of tissue after a thickness of about 6 mm. has been attained. At 20d̀ C. disks 10 mm. thick may be evenly depleted. Infestation experiments upon timber undergoing depletion showed that the attack by Lyctus is circumscribed by starch‐level and not by total nitrogen or soluble sugars.Under correct conditions of kilning, 1 in. sapwood plank can be rendered starch‐free in about 20 days: with larger sizes depletion is uncertain and probably uneconomic.The methods of starch and sugar analysis used in the work are appended.
A film technique for the biological evaluation of pyrethrum‐in‐oil insecticides for use against stored product insects in warehouses
Authors: Parkin E. A. , Green A. A. 
Published: February 2008

There is need for a technique whereby a given insecticidal preparation can be compared with a standard containing 0.8% (w/v) pyrethrin 1 in a heavy white oil and pronounced biologically equal or inferior to the standard within known and reasonable limits. A film method was investigated, Tribolium castaneum beetles being used as the test insects.Numerous factors which may influence the kill achieved are discussed. The results of preliminary work, planned to help in the standardization of some of these factors, are summarized.Several materials were tested to ascertain their suitability for reception of the insecticidal film and, as thin greaseproof paper showed promise, its possibilities were explored. Although 0.3 % pyrethrin I could be distinguished from 0.4%, 0.5% could not be distinguished from 0.8%, and the results throughout were very heterogeneous.Woven Nylon proved more satisfactory, since the test just failed to establish a significant difference between 0.6 and 0.8% pyrethrin 1. The origin of a pink coloration of the substrate, when T. castaneum beetles were confined on Nylon sprayed with pyrethrum in oil, was investigated.Whatman filter paper no. 544 proved the best substrate, and a comparative test on it will distinguish 0.65% pyrethrin 1 from the standard 0.8%; the limit could probably be raised to 0.7%.The influence of several factors on the homogeneity of the results was investigated, and the importance was shown of allowing beetles time to recover from the mechanical shock inherent in the method of counting into batches.Directions are given for carrying out the film technique for comparing preparations of relatively high pyrethrin content. The method does not measure the direct spray or fumigant action of the insecticide.The technique described is compared with the Peet‐Grady method for evaluating liquid household insecticides of low pyrethrin content. A simplified, but less accurate, design for the test is indicated.
The relationships of some viruses causing necrotic diseases of the potato
Authors: Bawden F. C. , Sheffield F. M. L. 
Published: February 2008

Potato virus B, and some other viruses with reactions in potato varieties different from any previously described, are strains of virus X. All produce intracellular inclusions which vary with different hosts and virus strains. Except with virus B, the inclusions are larger and more frequent in potato than in tobacco or tomato. All give systemic infection when inoculated to tobacco, tomato and potato varieties in which they are carried or cause mosaic symptoms; some give systemic infection when inoculated to varieties in which they cause top‐necrosis, whereas others give only local lesions.Potato virus C is a strain of virus Y: in tobacco and a few potato varieties both produce similar symptoms, but in those varieties in which Y causes leaf‐drop streak, C causes top‐necrosis. C causes systemic infection when inoculated to tobacco and to potato varieties in which it causes mosaic symptoms, but not when inoculated to potato varieties in which it causes top‐necrosis. Virus C was not transmitted by M. persicae. Viruses C and Y produce a few small intracellular inclusions in potato and tobacco.Virus A is not related to Y or X: no inclusions were found in plants infected with A alone.
The use of toxic polynitro derivatives in pest control
Authors: Batt R. F. , Martin H. , Wain R. L. 
Published: February 2008

The estimation of dinitro‐o‐cresol in winter washes consisting of petroleum oil, the cresol and emulsifier, must first involve the separation of the cresol from the other constituents present. A method applicable to the cases of emulsions compounded with various types of emulsiner failed when sulphite lye was present, and this was shown to be due to the action on the cresol of reducing sugars in alkaline solution. Avoiding an alkaline extraction until these interfering substances had been effectively removed led to an alternative method by which it was possible to separate D.N.C. in this type of emulsion.The results obtained demonstrate that the methods described are satisfactory for the routine estimation of D.N.C. in petroleum oil/D.N.C. emulsions.
Inert dust insecticides: Part II. The nature of effective dusts
Authors: Alexander P. , Kitchener J. A. , Briscoe H. V. A. 
Published: February 2008

The conditions required in an inert dust for it to become an effective insecticide against grain weevils have been investigated. Particle size and intrinsic hardness are important, but not the only, factors. In the case of carborundum, particles larger than 15μ are without action, probably because they do not adhere to insects, and effectiveness increases as the size is reduced from 10μ to about 2μ where a maximum effectiveness is reached.The effectiveness of a large number of different substances has been tested by a simple method which eliminates complications arising from particle size differences, and the results show a rough correlation of effectiveness with hardness. In general, materials softer than calcite are ineffective, and effectiveness increases with hardness, but the method of preparation of dusts is also important. Some dry‐ground powders are inferior to those wet‐ground, a phenomenon which appears to be due to some kind of surface change—possibly the formation of a Beilby polish layer. The effectiveness of some dusts can also be considerably altered by superficial chemical treatment.A theory is proposed, based on an experiment with an artificial membrane system, to explain the mechanism by which dusts promote evaporation of water from insects. It is suggested that clean crystalline surfaces of effective dusts can absorb, or in some way penetrate, the water‐resistant epicuticle.
Inert dust insecticides: Part III. The effect of dusts on stored products pests other than Calandra granaria
Authors: Alexander P. , Kitchener J. A. , Briscoe H. V. A. 
Published: February 2008

The inert dusts used in Parts I and II against the grain weevil have been found effective in vitro against a variety of other insects infesting stored products, both larvae and adults. The order, as well as the magnitude, of effectiveness of a series of dusts differs for different species, but the mechanism of action appears to be the same, viz. promotion of evaporation of moisture, leading to death by desiccation. In contrast to the results with Calandra, highly adsorbent dusts like charcoal are much more effective on larvae than are mineral powders.Dusts have a particularly striking action on the mealworm, and this case has therefore been investigated more fully. Dead mealworms when dusted do not lose water nearly as rapidly as live dusted ones.
Diseases of the gladiolus: II. Experiments on dry rot disease caused by Sclerotinia gladioli Drayt
Authors: Hawker L. E. , Bray R. J. , Burrows T. W. 
Published: February 2008

Inoculation experiments show that (1) young corms are more susceptible than old and become less susceptible as they develop, (2) infection of unwounded corms readily takes place, (3) inoculation of the top of an old corm is more effective than that of the side or base.The percentage diseased new corms produced from infected parent corms varies from o to 100 according to soil conditions. Disease is favoured by wet soil.Removal of ‘husks’ (leaf bases) increases the susceptibility of corms planted in contaminated soil, but the presence of husks is not an effective control. Dehusking did not increase the number of diseased young corms in an infected stock planted in new soil.No variety was strikingly more resistant than the rest.Good control was obtained when, corms of a diseased stock were treated with mercuric chloride, mercurous chloride (calomel) or the proprietary mercury fungicide Aretan. Calomel gave the most consistent results. Various other treatments were tested in small‐scale trials with some success. Red copper oxide, formalin and the proprietary mercury compound, Ceresan, were harmful.Sterilization of contaminated soil with formalin, mercuric chloride, Aretan or Uspulun gave good but not complete control. Formalin was the least effective.
A comparison of the toxicity of certain dyestuffs to the conidia of Fusarium culmorum
Authors: Dion W. M. , Lord K. A. 
Published: February 2008

The toxicity of a number of dyestuffs to the spores of Fusarium culmorum and Cercosporella herpotrichoides was determined by the slide‐germination technique. No attempt was made to distinguish between fungistatic and fungicidal activity.The toxicity of basic dyestuffs was unaffected by the acid radicle associated with the dye base.The high toxicity to Fusarium culmorum of malachite green dye base was reduced weight for weight and mole for mole by substitution of ethyl, propyl or butyl groups for methyl groups.The reduction of malachite green to malachite green leuco base removed toxicity.The substitution of amino groups and alkylated amino groups in benzene nuclei of triphenyl methane increased toxicity, whereas acid groups reduced toxicity. Sulphonation and carboxylation reduced toxicity to vanishing point.Alkylation of amino groups increased, but alkylation of benzene nuclei did not affect toxicity appreciably.When the central carbon atom of the triphenyl methane dyestuffs was replaced by nitrogen (e.g. Bindschedler's green) the diphenyl ammonium compounds were less toxic than the corresponding triphenyl‐methane compounds.The prevention of rotation of the aminated benzene rings by bridging, in the o‐position to central atom, with O or N, and so obtaining a planar molecule only slightly affected toxicity.Certain acid dyes stimulated fungal growth.The toxicity of the basic dyestuffs seems to depend not on one specific part but on the molecule as a whole, and within certain limits the structure may be varied without pronounced changes in toxicity.
Observations on the method of transmission of internal boll disease of cotton by the cotton stainer‐bug
Authors: Frazer Helen L. 
Published: February 2008

Results are presented to show that all the rules of proof for insect transmission of Nematospora by Dysdercus spp. have now been satisfied: viz. a close association of the insect with diseased plants in nature; visitation of healthy plants by the insect under conditions suitable for transmission of the disease; the presence of the pathogen in or on the insect in nature or following visitation to a diseased plant; and experimental production of the disease by insect visitation under controlled conditions. Hence it is claimed that Dysdercus spp. are proved vectors of internal boll disease of cotton.Fungal material as spores or mycelium is carried as an external contaminant on the mouth‐parts, although it is located in the deep stylet pouches, where protection is afforded and spore germination is possible.The fungus is cast off with the exuviae during moulting, but recontamination from exuviae or other sources in the environment occurs.The transmission is hence purely mechanical with the insect obligatory only in its function as a syringe to inject the fungus which is otherwise unable to reach its substrate. Insect and fungus can develop independently and the insect is apparently unharmed by the presence of the fungus.Nematospora spores also reach the intestine but do not appear to remain viable there and do not germinate.The fungus is believed to enter and leave the insect by the same route. The spores are well adapted in shape to reach the stylet pouches of the insect.No alternative morphological form of Nematospora gossypii within the insect has been found.The results do not lead to methods of control of the disease beyond those in practice‐trapping of insects, destruction of alternative host plants, and the alteration of time of planting to avoid insect attack.
Field trials of copper fungicides for the control of potato blight I. Foliage protection and yield
Authors: Large E. C. 
Published: February 2008

Results are given of eight replicated‐plot trials of a number of copper fungicides in comparison with standard Bordeaux mixture under relatively severe conditions of potato blight incidence, in Devon and Cornwall during the years 1941‐4.Recent methods of disease measurement on foliage were applied and developed; characteristic curves were obtained defining the conditions of trial and the relations between spray timing and progress of blight attack. The time interval between half‐decay dates for sprayed and unsprayed foliage was taken as a numerical criterion of the direct protective effect of spraying.A linear relationship was found to hold between probit foliage decay and time, and this was accounted for by the close correspondence of the probit curve to that derived from a growth law, da = Ca(A ‐ a)dt, where a denotes the percentage foliage area affected by blight at time t after the beginning of the attack.Methods were found for preparing dispersible mixtures of bentonite with active copper compounds for use in spraying. With such admixture, to improve adhesion, both cuprous oxide and copper oxychloride preparations nearly equalled Bordeaux mixture at the same copper dosage. Without sticker, and compounded with water‐soluble dispersing agents, these materials were equalled by Bordeaux mixture at half their copper dosage.Suspensions of metallic copper were found to have pronounced fungicidal effect against Phytophthora infestans. A bearing of this result on the fungicidal mechanism of cuprous oxide is discussed.Results from 103 pairs of twice‐sprayed and unsprayed plots of main‐crop potatoes in Devon and Cornwall in 1941‐4 showed a mean prolongation of growth due to spraying of 16 1/2 days, and a mean gain in total yield of 2 3/4 tons/acre; but the gain in yield resulting from a given prolongation of growth varied greatly, according to the stage of crop development at which the prolongation of growth began.Spray retention data, for correlation with foliage protection and yields, were obtained in all four years.