bluuebunny/crossref_metadata_2025_split huggingface dataset:
STUDIES IN BACTERIOSIS. III.: A BACTERIAL LEAF‐SPOT DISEASE OF PEOTEA CYNAROIDES, EXHIBITING A HOST REACTION OF POSSIBLY BACTERIOLYTIC NATURE.
Authors: PAINE SYDNEY G. , STANSFIELD. H. 
Published: February 2008

SUMMARY

A description is given of a disease of Protea cynaroides which is characterised by the development on the leaves of blister‐like spots of a brown colour, or of sunken spots of a brown colour with bright vermilion border.
The causal organism described is a bacterial parasite for which the name Pseudomonas Proteamaculans is suggested.
The attacked cells become filled with an amber coloured resin‐like substance in which apparently the bacteria become embedded and suffer a process of solution. This solution is either one of autolysis, or there may possibly be an analogy with the bacteriolytic action of the serum of an immunised animal.
The vermilion pigment is shown to be closely allied to phlorotannin red and the resin‐like substance is believed to be of the nature of a resino‐tannin.
A PHYTOPHTHORA ROT OF PEARS AND APPLES
Authors: WORMALD H. 
Published: February 2008

SUMMARY.In wet seasons Phytophthora Cactorum (Lebert et Cohn) Schröer sometimes produces a rot of apples and pears in this country, causing the fruit to fall.The rot in pears is characterized by a dark brown discoloration of the affected tissues accompanied by the appearance, at the surface, of clusters of sporangia, seen with the naked eye as glistening particles.In apples the discoloration is paler and sporangia are less readily produced; frequently the skin splits and the mycelium of the fungus is seen on the exposed surface as a whitish bloom.To keep the disease in‐check rotting fruit, whether on the ground or still on the tree, should be collected and destroyed.
DAILY PERIODICITY IN THE NUMBERS OF ACTIVE SOIL FLAGELLATES: WITH A BRIEF NOTE ON THE RELATION OF TROPHIC AMOEBAE AND BACTERIAL NUMBERS.
Authors: CUTLER D. WARD , CRUMP L. M. 
Published: February 2008

SUMMARY.

There is a daily fluctuation in the number of trophic forms of the three species of flagellates Oicomonas sp. (Martin), Cercomonas longicauda and Bodo sp., in the soil of arable fields.
The numbers of bacteria and trophic amoebae in the soil are correlated, varying inversely over a period of 14 days.
Temperature and rainfall appear to have no influence on the numbers of active protozoa in the soil.
THE KILLING OF BOTRYTIS SPORES BY PHENOL1
Authors: SMITH J. HENDERSON 
Published: February 2008

Summary

It is shown that if Botrytis spores be exposed to the action of 0–4 per cent, phenol, the spores do not all die simultaneously, but some die in a few minutes and some not till two or three hours have elapsed. The curve showing the numbers surviving at different times has a sigmoid shape.
If the strength of phenol be progressively raised, the curve becomes less and less sigmoid, approaching the logarithmic type of curve.
With the same suspension it is possible to obtain either a logarithmic or a sigmoid curve according to the strength of phenol used.
Both types of curve are shown to be explicable on the assumption that the individual spores differ in resistance and that a frequency curve showing the distribution in the resistance grades approaches the normal curve.
The influence of the number of spores used is shown to be very considerable; and the consecutive transition from the sigmoid to the logarithmic type occurs, whether we raise the phenol strength, keeping the spore number constant, or reduce the spore number keeping the phenol constant, or use younger and younger spores.
BIOLOGICAL STUDIES OF APHIS RUM I CIS LINN. THE PENETRATION OF PLANT TISSUES AND THE SOURCE OF THE FOOD SUPPLY OF APHIDS1
Authors: DAVIDSON J. 
Published: February 2008

Summary.

The food of aphids is the cell sap of plants, which they obtain by penetrating the tissues by means of a flexible, chitinous, piercing organ, which is composed of the maxillary stylets and the mandibles.
The maxillary stylets are closely apposed, thus forming two canals, which extend to the extremity of the compound stylet thus formed. The dorsal canal is the suction canal along which the plant juices are conducted into the pharynx. The ventral canal is the ejector salivary canal down which the saliva is pumped into the plant.
The penetration of the piercing organ is brought about by the retraction of the labium and the forward prolongation of the “forehead.” The labium at its distal end grips the piercing organ in a pincer‐like manner.
With Aphis rumicis the piercing organ passes intercellularly through the cortex, only occasionally passing through individual cells. Eventually it reaches the vascular bundles.
The saliva is able to dissolve a passage for the piercing organ through the walls of the cells. It is also able to convert starch into sugar.
A well marked sheath, the stylet sheath, is formed round the piercing organ when it is in the plant tissues, its wall being composed of substances produced by the reaction of the saliva on the cell sap. It probably consists of callose and insoluble calcium pectate together with a deposition of tannin.
The saliva causes plasmolysis of the cells and disorganisation of the cell contents.
With Aphis rumicis on beans, the phloem elements of the vascular bundles are the chief source of the food supply, although other cells of the plant, such as the cortex and mesophyll of the leaf may be tapped for nourishment, especially when the plant is heavily infested. Frequently in Rumex, xylem vessels are tapped for food.
The presence of a thick cuticle may prevent young aphids from piercing into the tissues and inhibit a general infestation of the plant.
The sucking out process is usually intracellular, although intercellular suction sometimes occurs in the loose cortical tissue.
In the case of Macrosiphum on the rose, occasional cells react under the influence of the saliva, resulting in a cellulose thickening of the cell wall of affected cells.
The varying constitution and concentration of cell Bap in different plants is an important consideration in respect to the biology and physiology of aphids.
The more favourable development and reproduction of aphids on certain plants is probably associated with the nature of the cell sap, and an investigation of the cell sap of plants under varying cultural conditions and manurial treatment appears to be necessary.
The composition of the excrement of aphids, or honey dew, depends upon the species of plant and aphid concerned, and is in close relationship with the composition of the cell sap of the plant and the digestive processes of the aphid.
FUNGI ASSOCIATED WITH “DIE BACK” IN STONE FRUIT TREES. I.1
Authors: CAYLEY DOROTHY M. 
Published: February 2008

Summary.

Diaporthe perniciosa, first isolated by Marchal from rots in stored fruits, has proved to be parasitic and one of the causes of “die back” in stone fruit trees.
The various strains of D. perniciosa isolated from “die back” on peach and different varieties of plums have proved to be parasitic, morphologically identical, and cause definite wilt and “die back” on peach, plum, apricot and nectarine. Cross inoculations of the same organisms on two year old wood of Prince of Wales plum have so far not brought about typical symptoms of “die back,” but considerable disturbance, accompanied by gumming, has occurred at the points of inoculation. A strain obtained from apricot, which shows morphological differences, has also been proved to be capable of causing “die back” on peach and apricot. All the controls remained healthy.
The progress of D. perniciosa in the host tissue is slow; infection occurs a considerable time, in some cases years, before any external symptoms appear. The mycelium permeates the internal tissues more especially the medullary rays, cortical tissues, phloem cambium, and vessels.
D. perniciosa has a pycnidial or Phomopsis stage with “a” and “b” spores, and a perithecial or Valsa stage with numerous eight‐spored asci. The pycnospores emerge as whitish tendrils or globules through numerous lenticel‐like slits in the bark; the perithecial necks are long and protrude mostly through the same slits as the tendrils, and the ascospores are given off either through the ostiolum at the tip of the neck of the perithecium, or may burst through any part of the neck.
The external symptoms are sunken areas and longitudinal slits in the bark; elongated strands of numerous lenticel‐like transverse slits through which tendrils and perithecial necks emerge; rapid wilt and browning of the trees in summer, or premature yellowing and fall of the leaves in the autumn.
The internal tissues are discoloured and secondary thickening arrested.
The pycnidial stage occurs on living or more or less moribund bark, the perithecial stage on the parts which are dead.
D. perniciosa shows a certain degree of polymorphism on the host plant; on artificial media this polymorphism is much more marked.
The Phomopsis stage of D. perniciosa grows and sporulates well on artificial media, but perithecia develop sparingly in cultures from pycnospores.
Cultures of mass infections of ascospores of D. perniciosa have given rise in some cases to the Phomopsis stage with “a” and “b” spores; in others no “b” spores could be found. Mono‐ascospore cultures develop the pycnidial stage very sparingly, and no “b” spores have been observed in any of the cultures. Large numbers of perithecia develop in mono‐ascospore cultures on various media.
STUDIES ON THE SEX‐RATIO AND RELATED PHENOMENA
Authors: PARKES A. S. 
Published: February 2008

Summary.

The existing work on the influence of the litter size on the sex‐ ratio shows very erratic results, and the new work embodied in this paper is rather more coherent.
It is clear, however, that multiple births in animals which are normally polytocus are somewhat different from multiple births in animals which are normally monotocus.
Before any attempt can be made to arrive a t the nature of the influence of the size of litter on the sex‐ratio it is essential to consider the factors which govern the size of the litter. Hammond(1) has shown that the number of eggs fertilised and the amount of foetal elimination are the two main factors controlling the size of litter. The first of these factors can scarcely affect the sex‐ratio, while the second, on the other hand, very well may have such an influence.
In view of the complexity of the interaction of these two factors any great coherence in the resulting sex‐ratio could hardly be expected.
THE‐ TOXIC ACTION OF COAL GAS UPON PLANTS
Authors: WOFFENDEN LETTICE M. , PRIESTLEY J. H. 
Published: February 2008

Summary.

Further experiments upon the effect upon the plant of atmospheres contaminated with coal gas, lend support to the view that this effect is mainly produced as a result of the mobility of unsaturated fatty substances in the plant walls in the presence of unsaturated gaseous hydrocarbons present in the coal gas.
Unsaturated fatty acids appear to be normal constituents of the meristem wall and in the presence of these unsaturated gaseous hydrocarbons they migrate towards the plant surface leaving the meristem walls more permeable. As a result, premature vacuolation and extension of the cells of the meristem take place. A failure of the primary endodermis in root and etiolated stem, owing to the absence of the fat impregnated Casparian strip, is frequently associated with this greater mobility of the unsaturated fatty acids. The normal green stem is indifferent to traces of coal gas because the fatty substances leave the meristem walls and accumulate in the surface wall at a very early stage of development.
The development of the cork phellogen in the stem of Sambucus is briefly traced, and the effect of coal gas upon this stem at different developmental stages is described.
The effects described are best interpreted on the assumption that at a very early stage of their formation, the cork cells cut off from the phellogen are very susceptible to the presence of coal gas. At this stage these cells become distended with water, and the fatty acids diffusing from the protoplast, fail to remain in and on the walls so that no suberin lamella is formed.
These results are entirely in accordance with the effects of coal gas upon the differentiating cells of the apical meristem cf etiolated stem or root and can be explained by the greater mobility of unsaturated fatty acids in the presence of the gaseous unsaturated hydrocarbons present in the coal gas.
The experimental results are also in accord with those ot earlier investigators. They suggest that coal gas will not be toxic to cork enveloped tissues except in the case of leakage from buried gas mains around the root systems of the plant; entry of pathogenic organisms will then be facilitated by che proliferated, unsuberised tissue formed from the cork phellogen.
The proliferated tissue formed from the cork phellogen in these experiments with coal gas appears to be suggestive in connection with the aerenchyma formed upon plant surfaces immersed in stagnant water.
THE EFFECT OF IODINE ON SOILS AND PLANTS
Authors: BRENCHLEY WINIFRED E. 
Published: February 2008

Summary.

No definite evidence of partial sterilisation with iodine was obtained when a number of different soils were treated with various combinations and strengths of iodine, the bacterial numbers with different treatments varying either very little or inconsistently. A suggestion of beneficial action with iodoform was obtained, if the right conditions could be found.
Germination of tomato seeds in “sick” soils was not affected by treatment with iodine in sodium iodide, and the initial vigour of treated and untreated plants was very similar.
The loss from “damping off” of tomato seedlings was not reduced by treatment before sowing, over a wide range of concentrations of iodine in sodium iodide.
Germination of mustard is either inhibited or badly checked by strong doses of iodine. In the latter case some of the plants eventually make a striking recovery and ultimately surpass the untreated controls in green and dry weight. If some time elapses between treatment and sowing the toxic action of iodine disappears and the mustard is unaffected, showing neither the initial toxic effect nor the later recovery and stimulation.
Barley is decidedly more sensitive than mustard to the toxic action of iodine, as germination is inhibited by a smaller dressing. With an amount of iodine that allows the seeds to germinate, though checking them badly, the plants frequently die off and never make the recovery nor show the stimulation of mustard under similar circumstances. With various intervals between treatment and sowing barley is still killed off at a time of sowing and with a strength of iodine that allows mustard to make its greatest recovery.
The various means whereby iodine may be put out of action in the soil are discussed and the suggestion is made that iodine might possibly have some specific and effective action if means could be found to prevent it from being converted from the elemental state so rapidly as appears usually to be the case.
Although no definite partial sterilisation effect has been obtained and though mustard and barley show little or no significant reaction, the possibility is not excluded that other agricultural crops, e.g. mangolds and sugar beet, might be benefited by the use of small amounts of iodine in addition to the usual fertilisers.
OBSERVATIONS ON THE IMPROVEMENT OF POOR PASTURE IN THE WEST RIDING OF YORKSHIRE
Authors: LYNN J. C. , LYNN D. ANDERSON 
Published: February 2008

SUMMARY.There are large areas of rough hill pasture in the West Riding of Yorkshire which are covered with a fibrous mat of undecomposed vegetable matter 1–3 ins. thick, and whose herbage falls naturally into two types, according to whether Nardus or Agrostis predominates. On such land lime forms an important ameliorative agent, breaking up the mat, decreasing the Nardus, encouraging the finer grasses, and inducing a vigorous growth of clover.It is shown that on reasonably dry land growing from 30–40 per cent, of Nardus stricta, 15–20 per cent, of Festuca ovina, and a conspicuous amount of Galium saxatile, Luzula campestris and Potentilla tormentilla, suitable applications of lime effect a striking improvement, which may be maintained for as long as 60 years; that lime followed by basic slag produces still better results; that basic slag alone has no effect.Where Agrostis predominates the mat is more open in texture and usually thinner than that associated with Nardus. On such land a satisfactory improvement is effected in certain cases by Iime; and in others, where the mat does not exceed 11/2 ins. in thickness, by basic slag alone. A great change is observed in the quality and palatability of the Agrostis as a result of such treatment.Even on lower‐lying and better‐class pastures in this district most beneficial results may be obtained from dressings of lime.
ON CHLOROPS TAENIOPUS MEIG. (THE GOUT FLY OF BARLEY)
Authors: FREW J. G. H. 
Published: February 2008

SUMMARY. Chlorops taeniòpus passes through two generations per year. The winter generation is mainly upon couch grass but also occasionally upon winter wheat or barley or upon self‐sown wheat or barley. The summer generation is mainly upon spring barley but in seasons unfavourable to the fly couch grass may be utilised. Very rarely wheat is a skimmer host plant. The life‐history is described in detail.The type of distortion caused to the host plant depends on the stage of growth of the plant when attacked and the degree of distortion of the plant depends upon the rate of growth at the time of attack.The relation of the fly to the different kinds of host plants is described particularly as regards the winter generation, and is shown to vary with such factors as date of emergence of the flies, weather conditions during the oviposition period and amount of growth of the different kinds of host plants.In dull and cool weather the flies will lay few eggs but are stimulated to rapid egg laying by bright and sunny weather. A single fly may lay about 150 eggs. More than one act of coitus is necessary to fertilise all the eggs which a ♀ is capable of laying. The length of life of the imagines is probably about a fortnight for flies emerging in spring but may be over two months for the autumn emerging flies.Certain manures (particularly superphosphate) are shown to have a marked beneficial effect in reducing the infestation of summer barley by gout fly. The effect of the manures is shown to be due entirely to their stimulating effect upon the maturing of the ear and the growth of the ear‐bearing internode.It is shown that while small dressings of nitrogenous manures may reduce infestation, large dressings will not reduce it and may have a tendency to retard growth of the ear and so increase infestation.Early sowing of spring barley is shown to be efficacious in preventing infestation by gout fly.Preventative measures suggested are early sowing of spring barley, good cultural conditions of the soil, and manuring (e.g. with superphosphate or farmyard manure) to stimulate early growth.
STUDIES IN BACTERIOSIS
Authors: MEHTA MANECK M. , BERRIDGE EMILY M. 
Published: February 2008

SUMMARY.B. marginale, the causal organism of a disease of lettuces described by Miss N. Brown in 1918, appears to be identical with the well‐known B. pyocyaneus. They agree in their morphological and cultural characteristics, and the latter has been shown to be capable of attacking young lettuce leaves and producing disease similar to that due to B. marginale.
INFECTION EXPEKIMENTS WITH WART DISEASE OF POTATOES. SYNCHYTRIUM ENDOBIOTICUM (SCHILB.) PERC.
Authors: GLYNNE MARY D. 
Published: February 2008

SUMMARY.A study of certain conditions controlling infection of potatoes by the winter sporangium of Synchytrium endobioticum in the soil and by the summer sporangium in the laboratory has been made with a view to finding a reliable method of pot experiment to serve as a basis in soil sterilisation research, and a method for testing immunity or susceptibility more rapidly than is at present done in the field.Experiments on infection by the winter sporangium in the soil have shown that a very high degree of soil moisture is necessary to ensure infection but this need not be present during the whole of the growth period. It appears most effective when the wet period is in the second month.A high percentage infection is obtained in potato plants grown in soils of very varying physical character.Under the conditions of pot experiment the wart disease organism survives in the soil in the absence of the potato plant for a period of at least a year. There appears to be a dormancy period of about six weeks between soil infection and sporangial germination. The relation of numbers of sporangia in the soil to the incidence of disease is discussed.When favourable conditions were maintained 80–100 per cent. of the plants tested were found to be infected within a period of three months, even in varieties which in the field appear least susceptible. Under conditions less favourable to infection the relative susceptibilities of the several varieties become clearly marked. No wart disease was found under any conditions on immune varieties.Infection of various plants other than the potato was attempted. Small warts were found on three varieties of tomato and on Solanum nigrum and S. dulcamara, but none on five other varieties of tomato, on Datura Stramonium, Salpiglossis sinuata, Eyoscyamus niger, Atropa belladonna, Lycium chinense or on many common weeds grown in infected soil.A method is described for infecting sprouting tubers with wart disease by means of summer sporangia. Susceptible varieties subjected to this treatment develop young warts within three weeks, while immunes remain clean. The method can therefore be used for testing immunity or susceptibility in the laboratory.
STUDIES ON CONTACT INSECTICIDES: PART I. INTRODUCTION AND METHODS. PART II. A QUANTITATIVE EXAMINATION OF THE TOXICITY OF TEPHROSIA VOGELII HOOK. TO APHIS RUMICIS L. (THE BEAN APHIS).
Authors: TATTERSFIELD F. , GIMINGHAM C.T. , MORRIS H. M. 
Published: February 2008

SUMMARY.1. The first part of this paper forms a general introduction to investigations carried out on contact insecticides. The methods used are briefly described and some consideration is given to the mode of expressing results.2. The second part deals in detail with the insecticidal properties of Tephrosia Vogelii Hook. which, with other species of this genus, occurs abundantly in many parts of the world. The aqueous and alcoholic extracts of the leaves and seeds of T. Vogelii are shown to be highly toxic to Aphis rumicis L., the toxicity being of the same order as that of nicotine. Extracts of the stems have not proved so poisonous.3. The plants of the genus Tephrosia seem to offer possibilities for practical use as insecticides and it is hoped to extend the work in this direction.