bluuebunny/crossref_metadata_2025 huggingface dataset:
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

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

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

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

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

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

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

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

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

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

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.
THE FERN MTTE. (TARSON EMUS TEPIDARIORUM, WARBURTON)
Authors: CAMERON W. P. LEGERWOOD
Published: February 2008

SUMMARY AND CONCLUSION.

Fern mite (Tarsonemus tepidariorum, Warburton) is of distinct economic importance. It attacks the younger parts only of the fern (Asplenium bulbiferum and its varieties), causing the fronds to become. distorted and the plant to be dwarfed so that it is unsaleable. The disease spreads rapidly in a greenhouse due to the rapid multiplication of the mite and the very short life‐cycle of 17 days on the average. All stages of the pest may be found during the summer, and the winter is passed mainly as an adult female, although a few eggs may also be found at that time. The mites spread from one nursery to another by the introduction of infested plants; from one plant to another by crawling from leaf to leaf where these touch, and probably by walking along the surface. of the moist earth; and by the planting of young “pips” taken from infested parents. The disease is difficult to control.

Preventive measures offer more chance of success than do remedial. The young “pips” should be planted clean, and then kept free from the pest by means of deterrent sprays. The “pips” are treated with some insecticide before planting.

Badly infested plants should be burnt and the soil and houses should be sterilised.

It is essential to produce healthy plants. To obtain this, certain factors are important, such as proper ventilation, adequate drainage and the correct degree of temperature and humidity.

Potash manures and lime are good. Nitrogenous manures should be sparingly.

Rotation of the greenhouse crops is advisable.

Plants would be produced clean, if they could be propagated from spores.
THE ANATOMY OF THE LEAF‘ OF A NEW FIBRE PLANT
Authors: DENNISTON R. H.
Published: February 2008

RESUME.

The valuable fibre portion of this leaf consists in the fibre groupa scattered through the parenchyma of the abaxial portion of the leaf and in the groups of fibres accompanying each fibro‐vascular bundle.

The bast fibres are composed principally of cellulose, as indicated by their ready solubility in copper‐oxide‐ammonia solution, and by their violet colour when treated with zinc‐chlor‐iodine and blue colour with iodine and sulphuric acid.

The fibres are not pure cellulose, however, as is shown by their red colour when treated with phloroglucin, and their yellow colour when treated with anilin sulphate.

The outer part of the fibre‐wall shows clear evidence of spiral structure under the action of cuprammonis. The treated fibre presents the appearance of a series of beads of unequal size. After repeated applications of the reagent, the constricting portion of the fibre swells and loosens. All portions of the fibre give the cellulose reaction with zinc‐chlor‐iodine, but the spiral constricting portion takes a violet colour in advance of the inner portion of the fibre and can then be seen very distinctly.
STUDIES ON OSCINELLA PRIT LINN.: SUPPLEMENTARY DATA ON THE RELATION BETWEEN VARIETAL DIFFERENCES OF OAT PLANTS AND SUSCEPTIBILITY TO INFESTATION
Authors: CUNLIFFE NORMAN , FRYER J. C. F.
Published: February 2008

During the year 1924 additional data, in relation to varietal resistance to attack, were collected by repeating as nearly as possible the investigation conducted during the previous year, with the exception that only those varieties of oat were used, which were most (Goldfinder and New Abundance) and least resistant (Superb and Supreme).

During the second season, during which, on the whole, conditions were unfavourable to damage by frit fly, varietal differences were again effective so far as stem infestation was concerned. The two varieties, Goldfinder and New Abundance, were significantly resistant as compared with the variety Supreme, similar differences being observed in the two seasons. Very late sowing indicated that varietal differences among very young plants were ineffective in influencing extent of infestation.

Small significant differences were observed in relation to the grain infestation, but from the evidence available it would appear that constant values for these differences are unlikely to occur over a period of years, because extent of infestation is largely dependent on the history of the crop during the early growing period.
INFLUENCE OF LEAD AND THE METALLIC IONS OF COPPER, ZINC, THORIUM, BERYLLIUM AND THALLIUM ON THE GERMINATION OF FROGS‘ SPAWN AND ON THE GROWTH OF TADPOLES1
Authors: DILLING WALTER J. , HEALEY C. W.
Published: February 2008

In these experiments lead salts proved to have a higher inhibitory influence on the germination of the frog's ovum than the salts of other metals tested and they also proved capable in weaker solutions of retarding the growth of tadpoles without causing their early death. Of the other metals tested thorium was active in checking germination; the others much less so. Zinc, copper and thallium were more toxic to the emerged tadpoles than lead. Beryllium was relatively inert. Hanzlick and Presho's observations on pigeons fed with pure metals led them to conclude that, as regards the power of reducing body weight, the action of other metals was much less than that of lead, which they regard as having a specific toxicity (6). The present writers do not consider that these effects are “specific” or peculiar to lead, but they are relatively more marked with its salts. Locke's (9) experiments with tadpoles showed that lead was less directly toxic to them than zinc and much less than copper; this we have confirmed, but our experiments suggest that the “oligodynamic” action of lead decreases as the embryo ages.

These experiments suggest that lead is more toxic to germinating tissues than the other metals tested and afford an explanation of its abortifacient action on the basis that it is much more toxic to the embryo than to the adult tissues of the parent. Subsequent experiments by Blair Bell, Hendry and Annett on pregnant rabbits have shown that after injections of colloidal lead there occurs a coagulation necrosis in the ectodermal tubules (trophoblast) of the foetal placenta; this rapidly spreads throughout the foetal ectoderm and into the adjacent superficial tissues of the maternal placenta so that the necrotic foetal placenta is soon cast off. They conclude that lead has a selective affinity for the chorion epithelium and that abortion can be produced by the action of lead on the foetal ectoderm (trophoblast) without the maternal organism being in any way affected.

On the findings of the present experiments these observers tried thorium as a substitute for lead but found it had no specific or toxic action on the chorion epithelium and that the abortifacient action of copper and thallium was uncertain and due to haemorrhage in the maternal tissues of the uterus (2).

It has also been possible to confirm by these experiments some of the essential features recorded in the literature, e.g. (a) the toxicity of lead towards the female germ cell as higher than that to the male cell as was indicated in Weller's (15) experiments; (b) the greater susceptibility of very young animals to lead and progressive tolerance as the animal ages; and (c) the retardation of growth in the tadpole is comparable with the undersized offspring delivered from the mammal and the retardation of growth noted after birth by Weller (16).
AN INTRODUCTORY NOTE ON TWO BACTERIA CAUSING AN INTERNAL ROT OF COTTON BOLLS
Authors: HOPKINS J. C.
Published: February 2008

Two organisms have been isolated which are capable of producing an internal rot of at least five varieties of cotton bolls.

Inoculation experiments and resulting physiological phenomena are described and the similarity between the two rots demonstrated.

The association of one organism with the anthracnose fungus is pointed out and dual infection of a number of varieties of cotton bolls discussed; the resistance of Sea Island and Cauto varieties to the disease is suggested.

Detailed descriptions of both organisms and their reactions to various standard media are given.
FURTHER EXPERIMENTS ON THE USE OF SULPHUR IN RELATION TO WART DISEASE OF POTATOES
Authors: ROACH W. A. , BRIERLEY Wm. B.
Published: February 2008

Plots of light sandy soil at Ormskirk carefully fenced in to prevent re‐contamination were treated with sulphur at rates of 10 cwts. and 15 cwts. per acre. The sulphur was incorporated by means of the Simar Rotary Tiller. A planting of King Edward and a replanting of Arran Chief varieties in the treated plots almost completely failed to grow. On the few plants which developed, Wart Disease was present in less quantity than on the plants in the untreated controls.

A plot of heavy clay soil at Hatfield was treated with 3 tons of sulphur per acre incorporated by means of the Simar Rotary Tiller. Plants of King Edward variety grew well but showed a considerable amount of Wart Disease.

Plots of land at Ormskirk which in 1924 had received amounts of sulphur varying up to one ton per acre were in 1925 given a dressing of lime and planted with Majestic variety of potatoes. No effect of the previous treatment on the crop was apparent.

We are indebted to the Piccard Pictet Company for the loan of the 4 h.p. Simar Rotary Tiller used in these experiments.
STUDIES ON CONTACT INSECTICIDES
Authors: TATTEESFIELD F. , GIMINGHAM C. T. , MOREIS H. M.
Published: February 2008

An account is given of laboratory experiments on the toxicity to Aphis rumicis L. of extracts of a considerable number of plants, including some tropical fish‐poisons, Lupins, Broom, Gorse, Lobelia and others.

Alcoholic extracts of certain tropical plants used as fish‐poisons are shown to have a high toxicity under the conditions of the experiments. The roots and stems of White Haiari, and the stems of Black Haiari (both species of Lonchocarpus from British Guiana), the roots of Tephrosia toxicaria and the leaves of T. Vogelii all possess notable insecticidal properties. The roots and stems of T. Candida are less toxic.

Preliminary experiments indicate that the Haiaris and T. Vogelii and T. toxicaria, when tested as stomach poisons, exert both a repellent and toxic action to caterpillars.

Certain derivatives isolated from these plants were tested. The most toxic substance obtained from the Haiaris is shown to be identical with tubatoxin, the crystalline poison found in Derris elliptica. Tubatoxin proved to be several times more toxic than nicotine. In the case of Tephrosia Vogelii and T. toxicaria, the most toxic substances isolated were resinous in nature. Crystals closely corresponding to tephrosin, as isolated by Hanriot, were less toxic.

A number of alkaloids was also investigated. Cytisine and lobeline, known to have a physiological action on higher animals similar to that of nicotine, were found somewhat less toxic than nicotine to aphides. Eserine was the only other alkaloid tested which approached nicotine in toxicity.
INVESTIGATIONS INTO INSECTICIDES FOR ROOT MEALY BUG AND ROOT APHIS
Authors: SAUNDERS WINIFRED H.
Published: February 2008

Of the list of possible remedies the following are the least desirable for using on a large scale for the reasons stated.

Nicotine Uncertain in its action and being poisonous must be used cautiously.

Pyridine Highly offensive odour.

Petroleum Inflammable. Bugs dislike it, they often leave the pots and under certain conditions they may escape death.

Methyl alcohol Inflammable, action slow.

Acetone Will not mix with water—injections into the soil are impracticable.

Fuel oil Bugs escape from the pots.

Miscible fusel oil No effect.

The three following stand out as being the most effective and suitable:

Tetrachlorethane (Westoran)

Trichlorethylene (Westropol)

Potassium sulpho‐carbonate

The root mealy bug and root aphis living under similar conditions in pots, adopting similar methods of feeding and protection, respond similarly to any particular treatment. The grower may, therefore, cope with both pests by the application of a common remedy.
INFLUENCE OF PROTOZOA ON THE PROCESS OF NITROGEN FIXATION BY AZOTOBACTER CHROOCOCCUM
Authors: CUTLER D. W. , BAL D. V.
Published: February 2008

Increased nitrogen fixation by Azotobacter chroococcum in the presence of protozoa, as shown by Nasir, has been confirmed

The same effect is found, using soil as a medium.

There is a definite relationship between the efficiency of the strain used, the incubation period and the concentration of mannitol employed.

The feeding action of Colpidium colpoda and Hartmanella hydlina on Azotobacter has been demonstrated.

The reason for increased nitrogen fixation appears to be due to the efficiency of Azotobacter being maintained for a longer period.
CARBON DIOXIDE IN RELATION TO GLASSHOUSE CROPS
Authors: OWEN O. , SMALL T. , WILLIAMS P. H.
Published: February 2008

The rate of germination of tomato seeds is practically unaffected when the seed boxes are exposed to atmospheres enriched with carbon dioxide.

Increases of over 20 per cent, in marketable tomato crops result when the plants are subjected to atmospheres containing 0.6 per cent, of CO2 for 1 or 2 hours daily.

Cucumbers heated with atmospheres containing 0.9 per cent. CO2 for 1 hour daily showed an increase in crop of 16 per cent.

In the case of the 1925 tomato crop, and to a less degree of the 1924 crop, a considerable part of the increased picking is manifested in June, when market prices are high.

In its effect on the crop carbon dioxide generated slowly at the soil surface is not as beneficial as the gas when generated quickly and mixed with the air surrounding the plants.

Plants grown in houses which have been used for carbon dioxide experiments show an increased susceptibility to infection by Colletotrichum atramentarium.

When carbon dioxide is generated quickly in a house an appreciable loss of this gas always occurs. This loss appears to be independent of temperature and varies directly with the amount of ventilation.

Experiments with apparatus devised for the use of carbon dioxide on a commercial scale were unsuccessful owing to the inadequacy of the apparatus.
A STUDY OF TWENTY‐FOUR STRAINS OF ACTINOMYCES AND THEIR RELATION TO TYPES OF COMMON SCAB OF POTATO
Authors: MILLAED W. A. , BURR SYDNEY
Published: February 2008

The difficulty of reconciling various cultures of the scab organism with any one defined type of A. scabies (Thaxter) Güssow is discussed.

Inclusion of all such cultures into one A. scabies group has no justification.

A technique has been evolved whereby the cultural characters of Actinomyces may be maintained in sub‐culture.

Twenty‐four Actinomyces strains were isolated from potato scabs and other sources, and the cultural and morphological characters of these have been worked out and described.

Three pairs of duplicate strains appeared, but with these exceptions, the differences between the strains were of specific rank.

One of the species appears to be identical with Thaxter's original scab organism and is thus referred to A. scabies (Thaxter) Güssow; the remainder are new and have accordingly been named.

Eleven of the species were found to produce scab on potatoes.

The various type a of common scab have been defined, and it has been shown that type of scab is dependent on the infecting Actinomyces species. The variety of potato may modify but cannot materially change this type.

A. scabies (Thaxter) Güssow (emend. M. and B.) produced a deeply furrowed scab apparently identical with the “Deep Scab” described by Thaxter. This species was also found to attack the roots and stolons of potato plants.

The occurrence of scab in virgin soils and the predominance of certain scab types in certain soils and in different years are discussed.
THE INCIDENCE AND INTENSITY OF PUCCINIA GLUMARUM ERIKS. AND HENN., ON WHEAT INFECTED AND NON‐INFECTED WITH TILLETIA TRITICI WINTER, SHOWING AN APPARENT RELATIONSHIP BETWEEN THE SUSCEPTIBILITY OF WHEAT PLANTS TO YELLOW RUST AND TO BUNT
Authors: WESTON W. A. R. DILLON
Published: February 2008

In the season 1925–6 an interesting relationship was noticed between yellow rust of wheat, Puccinia glumarum and bunt or stinking smut of wheat, Tilltia tritici; it was observed that:

Bunted Little Joss wheat plants were badly rusted and that plants free from bunt were free or comparatively free from rust.

Bunted plants of other wheat varieties were definitely more rusted than plants free from bunt.

It is suggested that rust resistance which cannot be broken down artificially may be broken down by natural contamination of wheat with the bunt fungus.
THE LIFE HISTORY AND BIONOMICS OF A BRITISH PHYTOPHAGOUS CHALCIDOID OF THE GENUS HARMOLITA (ISOSOMA)
Authors: JAMES E. C.
Published: February 2008

This paper is a contribution to our very scanty knowledge of the British Harmolita, a phytophagous genus of the superfamily Chalcidoidea (Hymenoptera). Many species of this genus are pests on cereals and cultivated grasses; one species, Harmlita tritici, is the notorious joint‐worm of America and Russia, whilst species attacking many other cereals and grasses have been recorded in Europe and America. An account is here given for the first time of the life history and biology of a British species of Harmolita, namely Harmolita graminicola, which is a gall former on couch grass (Triticum repens).

The larva of another undetermined species of Harmolita, also gallicolous on Triticum repens is figured and briefly described.

The adult of Harmolita graminicola begins to emerge in the last week of June and continues to appear during the first week of July. When the inflorescence has appeared through the sheathing leaves the female fly will not lay eggs on them. One egg is deposited on each culm just beneath the rudimentary inflorescence, the ovipositor of the fly piercing the sheathing leaves in order to reach the desired position. The Harmolitae of both species were bred in captivity and the length of the period of incubation of the egg was found to be between three and four weeks. Experiments were conducted to ascertain whether parthenogenesis occurred in this species. The results were negative although perhaps not numerous enough to be conclusive.

The larva possesses four instars and moults three times whilst feeding, another moult occurring at pupation. The larval instars can be differentiated most exactly by the state of development of the sub‐apical tooth on the mandible. The sub‐apical tooth is absent from the mandibles of the first instar; only incipiently developed in the second instar; better developed in the third and fully formed in the fourth instar. The larva becomes full fed in October and hibernation takes place in the larval stage. Pupation begins to occur near the end of April but the great majority pupate in the middle of May.

There is a short semi‐pupal stage of from 12 to 24 hours duration immediately before the pupal moult takes place. The pupal stage lasts about 40 days and there is only one generation each year. The larva of Bracon erythrostictus (Lyle) was found to be parasitic on Harmolita in the latter's larval stages; no other insect parasites were found. Both Harmolita graminicola (Gir) and the undetermined species refused to breed on wheat or any other plants of the Triticum genus although many attempts were made to induce them to do so.
ON FORMS OF THE HOP RESISTANT TO MILDEW (SPHAEROTHECA HUMULI (DC.) BURR.)
Authors: SALMON. Prof. E. S.
Published: February 2008

Three varieties of hops which had previously shown complete resistance to the attacks of S. Human, became slightly infected in the greenhouse in the spring of 1926.

The susceptibility shown was only temporary; all the infected plants during May and June again acquired their power of complete resistance.

The conidia produced on an “immune” plant proved unable to infect that plant, although able to infect a susceptible variety.

It appears probable that abnormal weather conditions (possibly low temperature) brought about the temporary susceptibility.
GRAFTING EXPERIMENTS WITH VARIETIES OF HOPS RESISTANT TO TICE HOP POWDERY MILDEW, SPHAEROTHECA HUMULI (DC.) BURR.
Authors: SALMON Prof. E. S. , WARE W. M.
Published: February 2008

Twenty composite plants were built up by grafting either a scion of an immune variety of hop on a susceptible stock, or vice versa. Inoculation of young leaves of the scion, after a considerabll growth of the latter had taken place since grafting, showed that no change had been effected in the varietal immunity or susceptibility in relation to Sphaerotheca Humuli.

In the above experiments, scions of six different immune varieties were grafted on stocks of four different susceptible varieties and scions of four different susceptible varieties were grafted on stocks of five different immune varieties.

The results obtained render it improbable that immunity or susceptibility to S. Humuli is connected with any translocatable substance in the hop plant.
STUDIES ON CONTACT INSECTICIDES
Authors: TATTERSFIELD F. , GIMINGHAM C. T.
Published: February 2008

The toxicities to Aphis rumicis L. of the fatty acids from formic to stearic and of the sodium and ammonium salts and methyl esters, applied as spray fluids, have been quantitatively determined. Two un‐saturated acids, undecenoic and oleic, are included.

There is a rise in toxicity of the acids with increase of molecular weight as the series is ascended from acetic to undecylic acid. Formic acid is exceptional. Beyond undecylic acid, there is a fall in toxicity, and acids higher in the series than tridecylic show only slight toxic action.

The sodium salts of the fatty acids are in most cases much less toxic than the corresponding acids, though the difference is less marked with the higher acids. Oleic acid and sodium oleate are of the same order of toxicity.

The ammonium salts are also generally less toxic than the corresponding acids, but the differences are much less than in the case of the sodium salts. With some of the higher acids, e.g. myristic and oleic, neutralisation with ammonia increases toxicity. The relatively high toxicity of the ammonium salts may be due, at least partly, to liberation, by hydrolysis, of free fatty acid in a very finely divided state.

Methylation of the fatty acids reduces toxicity; all the methyl esters are less toxic than the acids or ammonium salts.

Both the ammonium salts and the methyl esters show, like the acids themselves, increase of toxicity with increase of molecular weight up to a certain point. The formates are exceptional.

The fatty acids do not show marked toxicity to the eggs of Belenia tetralunaria Hüfn. at concentrations below 2 per cent.

Possible relationships between certain physical properties (physical state. volatility, dissociation constants, partition coefficients and surface tension) of the fatty acids and their insecticidal action are discussed.

Determination of partition coefficients as between olive oil and water and comparison of the figures with the relative toxicities show a steady rise in toxicity with a decrease in the partition coefficients (water/oil) from acetic to capric acid. Formic acid is again exceptional. With lauric and oleic aoids there is a break in the correlation. The bearing of the solubility relationships of the acids on these results is considered.
SULPHUR TREATMENT OF SOIL AND THE CONTROL OF WART DISEASE OF POTATOES IN POT EXPERIMENTS
Authors: CROWTHER E. M. , CLYNNE MARY D. , ROACH W. A.
Published: February 2008

In a series of pot experiments on potatoes grown in an acid soil artiftcially infected with the wart disease fungus, treatments with sulphuric acid and various combinations of sulphur and calcium carbonate, yieldmg a wide range of soil reaction, gave almost complete freedom from infection when the acidity of the soil had been raised to a very high value (pH 3.4 or less).

Heavy dressings of calcium carbonate, alone or with sulphur, giving a soil reaction of pH 7.5 or more, also reduced infection.

The fact that partial and even, in one experiment, complete suppression of disease was obtained at lower acidities, where the effect on the disease was not closely related to the degree of acidity, supports the tentative conclusion already drawn from field experiments that sulphur in controning wart disease does not depend entirely on its effect in raising the acidity, but has also some other mode of action. Whether this toxicity which sulphur exerts apart from its effect on the acidity can be enhanced sufficiently to be of any practical value requires further investigation.
THE EFFECT OF HYDROGEN PEROXIDE ON YEAST GROWTH AND FERMENTATION
Authors: BROWN J. B. , WIKOFF H. L.
Published: February 2008

Hydrogen peroxide, when added in the form of superoxol to an aerated yeast molasses mash, is very toxic to the yeast, greatly inhibiting or entirely stopping yeast growth, fermentation and inversion.

The yeast yield without aeration in a mash of this kind is greatly diminished, while the other changes are only shghtly inhibited, the total loss of solids bekg appreciably greater than with aeration.

If the pH change in such an aerated mash is allowed to progress normally, a marked fall from 7.0 to 2.0 is observed, apparently due to the formation of organic acids, and to removal of ammonia from the ammonium salts.
THE EFFECT OF HEXYL RESORCINOL ON YEAST GROWTH AND FERMENTATION
Authors: BROWN J. B. , WIKOFF H. L.
Published: February 2008

Concentrations of 0.3 and 0.1 gm. of hexyl resorcinol per litre completely inhibit yeast growth and fermentation. Concentrations of 0.01 and 0.005 gm. only slightly inhibit.

Invertase action is not affected in the presence of 0.3 gm. of hexyl resorcinol per litre of mash.
EARLY MANIE'ESTATIONS OF POTATO BLIGHT (PHYTOPHTHORA IN FEST AN S DE BARY)
Authors: ALCOCK N. L. , McINTOSH A. E. S.
Published: February 2008

Observations during February, 1927, are recorded on nominally healthy potato tubers sprouted indoors in the laboratory of the Seed Testing Station, East Craigs, producing short diseased shood showing probable primary infection of Phytophthora infestans. At the end of the month probable cam of secondary infection occurred.
THE INSECT AND OTHER INVERTEBRATE FAUNA OF ARABLE LAND AT ROTHAMSTED. PBRT II
Authors: MORRIS H. M.
Published: February 2008

Samples of soil were taken from six of the plots of Barn Field on the farm of the Rothamsted Experimental Station, and the Insects and other Invertebrates found therein are recorded together with the approximate depth at which they occurred.

On these plots one receives no manure, one superphosphate only and one ammonium salts only, while of the other three, all of which receive dung, one receives superphosphate and potash, and another ammonium salts in addition.

The total number of Insects and other Invertebrates per acre in the undunged plots were 1,208,000, 1,410,000 and 1,734,000 respectively. Of these 673,000, 999,000 and 1,424,000 respectively were Insects. Similarly in the dunged plots the total numbers of Insects and other Invertebrates per acre were 12,948,000, 9,448,000 and 10,516,000 respectively, and of these 2,323,000, 2,215,000 and 4,677,000 gespectively were Insects.

Each sample was taken in five layers so that it was possible to record the approximate depth at which each individual occurred. The greatest number, both of Insects and of other Invertebrates, occurred in the upper five inches of the soil.

From the figures obtained in this investigation it appears that artificial manures have little or no effect on the soil fauna, while the effect of dung in increasing the numbers and the number of species of the fauna is very considerable.