bluuebunny/crossref_metadata_2025 huggingface dataset:
THE BIOLOGY OF THYSANOPTERA WITH REFERENCE TO THE COTTON PLANT: 2. THE RELATION BETWEEN TEMPERATURE AND LIFE CYCLE IN A SATURATED ATMOSPHERE
Authors: MacGill ELSIE I.
Published: February 2008

The life‐cycle of Thrips tabaci from oviposition to imaginal emergence, on cotton plants, under conditions of temperature varying between a mean maximum of 26.7°C. and a mean minimum of 11.25°C., and of relative humidity varying between a mean maximum of 92–4 per cent. and a mean minimum of 74–7 per cent., has a duration of 23–31 days, comprising an egg stage of 8 days, two larval stages with a combined duration of 10 to 14 days, a prepupal stage of 1 to 2 days and a pupal stage of 4 to 7 days.

Under laboratory conditions, in a constant saturated atmosphere, the percentage of larvae which transform into prepupae is not high at any temperature but reaches a maximum of 33.4 per cent. at temperatures near 21°C. The minimum effective temperature is below 7° and the maximum effective temperature is above 38°.

The high larval mortality is not wholly due to faulty technique, nor to the saturated atmosphere, nor to the artificial conditions. A similar high rate of mortality is believed to occur under field conditions.

The percentages of prepupae and pupae which transform are high at all temperatures between the minimum and maximum effective points, and would probably be absolute under conditions of perfect technique.

The length of the life‐cycle is decreased by increase of temperature. The average times of development plotted against temperature give, with minor corrections, an hyperbola similar to the developmental curves given by Krogh.
THE GERMINATION OF POA SPP.
Authors: NELSON ALEXANDER
Published: February 2008

The paper in its first part deals with the germination response, in the laboratory, of four species of Poa to variations of temperature, light and the nature of the moisture supply. The second portion deals with the same response of P. compressa to solutions of various salts used as moisture supply. The third part deals with the germination of P. compressa in the soil when all the above factors were varied. In the laboratory, alternation of temperature proved to be, generally, the most, efficient stimulant followed by light and a solution of potassium nitrate as moisture supply. P. compressa proved to be more sensitive than any of the other species considered, P. pratensis and P. nemoralis rather less so, while P. trivialis was almost insensible to variations of the conditions. In the soil. excess of light (sunlight) proved to be depressant. Some salts. e.g potassium nitrate, sodium nitrate, ammonium nitrate, etc., proved to be stimulating in solution culture, while salts of lead were depressant. As a general statement these salts, found to be stimulating in solution culture. proved to be more depressant in soil than those found depressant in the solution. Lead salts in the soil produced broader, deeper coloured leafage than the controls. Nitrites had a striking physical effect in preventing the drying up of the soil.
The Transmission Of “Mosaic” Disease In Hops By Means Of Grafting
Authors: THRUPP T. C.
Published: February 2008

In these experiments. where susceptible scions have been grafted on to “mosaic” stock, all developed “mosaic” symptoms with one exception. Circumstances were not favourable in this particular case and it. should be regarded as giving indecisive not negative evidence. From the other cases there is satisfactory proof that, the supposed “virus” can be transmitted up the growing bine.

With the “carrier” experiments, all the known susceptible sciens, which were grafted on to the “carrier” (M 45) stock, exhibited “mosaic” symptoms. The variety M 45 must, therefore. be regarded as capable of transmitting the disease to susceptible hops, and as being a “carrier.”

There is no evidence that the process of grafting can of itself in any way induce “mosaic” symptoms to pear in healthy susceptible hops, or in the “carrier” M 45
IMMUNITY OF POTATO VARIETIES FROM ATTACK BY THE WART DISEASE FUNGUS, SYNCHYTRIUM ENDOB IOTICUM (SCHILB.) PERC.
Authors: ROACH. W. A.
Published: February 2008

It is known that grafting together portions of two different plants is sometimes followed by changes in their chemical contents owing to permeation of each by substances formed in the other.

The present investigation is an attempt to determine by grafting together pieces of immune and susceptible plants whether the cause of immunity from wart disease of potatoes is carried by chemical compounds which can traverse unchanged a graft fusion layer or by those which are unable so to do.

For this purpose all the eight possible types of plants have been built up by grafting together root, shoot and tuber systems from either immune or susceptible plants.

In none of the experiments was the reaction of the tubers towards wart disease seen to be changed.

The deduction is therefore drawn that the cause of the immunity is not carried by any compound which is able to traverse the plant.

In this way the problem is considerably narrowed down, for it is now possible to eliminate many lines of attack as unlikely to be fruitful.

The suggestion is put forward that the examination of the proteins from immune and susceptible varieties by immunochemical methods is the most hopeful future line of attack.
THE DECOMPOSITION OF NAPHTHALENE IN THE SOIL AND THE EFFECT UPON ITS INSECTICIDAL ACTION
Authors: TATTERSFIELD F.
Published: February 2008

The insecticidal action of naphthalene and its duration in the soil have been studied.

When naphthalene is incorporated thoroughly with soil it shows a fairly potent toxic action on wireworms; uneven distribution lessens its efficiency as, owing to its low vapour pressure and consequent slow spread, it produces only a small zone of toxic action.

Naphthalene is slow in toxic action, taking three or four days to kill wireworms, as a consequence of which and of its repellent action to insects, if the chemical be unevenly distributed in the soil insects tend to move away from positions where toxic action would be exerted.

The persistence of the toxic action depends upon the soil type. In soils rich in organic matter, toxicity disappears more rapidly than in soils less rich in organic matter. Toxicity persists longer in sterile soils and in sand than in unsterilised soils, and in dry than in moist soils.

The rate of disappearance of naphthalene from soil has been determined. It depends very little upon volatilisation but almost entirely upon some factor inherent in the soil, which is more active in soils rich in organic matter than those poor in organic matter, and in unsterilised soils than in sterile soils.

Second and third doses of naphthalene added to the soil, when the first has disappeared, are decomposed more rapidly than the first dose.

The bacterial numbers of the soil are at first decreased by the addition of naphthalene, but there is a rapid rise during the period when acceleration in the rate of decomposition of the naphthalene is taking place. All the evidence indicates that the loss of naphthalene from the soil is mainly due to bacterial decomposition.

Experiments in sealed bottles indicate that the opening of the bottle and mixing of the sample expedite the disappearance of naphthalene from the soil.

The toxicity of α‐chlornaphthalene persists for a longer time in soils than naphthalene, and is decomposed at a slower rate. An admixture of naphthalene appears to induce a more rapid disappearance of the toxicity of the chlornaphthalene. α‐Chlornaphthalene is more toxic to plants than naphthalene.

Methods of estimating naphthalene are described. They depend on formation of naphthalene picrate. Picric acid can be more readily titrated by alkali in orange and yellow coloured light than in white light.

It was noted in several tests that the prolonged aeration of soils which had been heated and allowed to cool gave rise to formaldehyde.
THE TOXICITY OP CERTAIN SULPHUR COMPOUNDS TO SYNCHYTRIUM ENDOBIOTICUM, THE FUNGUS CAUSING WART DISEASE OF POTATOES
Authors: EOACH W. A. , GLYNNE MAEY D.
Published: February 2008

The toxieities towards the winter sporangia of Synchytrium endobioticum of certain of the simpler sulphur compounds which are at all likely to be formed when sulphur is added to soil were tested and compared with that of sulphuric acid.

Sulphuric (H2SO4), sulphurous (H2SO3), dithionic (H2S2O6), trithionic (H2S3O6), tetrathionic (H2S4O6), and pentathionic (H2S5O6) acids were toxic and this toxicity was of the same order in each case at the same hydrogen ion concentration. Their neutral salts were non‐toxic. These facts suggest that the toxicities of these acids are mainly due to their hydrogen ion concentrations.

Acidified solutions of sodium thiosulphate Na2S2O3, sodium hydrosulphite Na2S2O4 and sodium formaldehyde sulphoxylate were about ten times as toxic as sulphuric acid.

Evidence is brought forward which suggests that the toxicity of these acidified solutions, in excess of that accounted for by the hydrogen ion concentration, is due to the thiosulphuric acid present in each of them. In view of the experimental difficulties due to the instability of some of the compounds and the length of time taken by them to exert their toxic action on the fungus investigated, this conclusion must be regarded as tentative.

Of the other compounds tested sodium hydroxide was found to be a little more toxic than sulphuric acid and persulphuric acid about ten times as toxic; hydrogen peroxide, calcium polysulphide and sulphuretted hydrogen were only slightly toxic.
A GARDEN CHAFER, ATTACK
Authors: TAYLOR T. H. , THOMPSON H. W.
Published: February 2008

The good effects obtained by capturing the beetles when they are swarming on bracken last apparently for several years.

A form of trap is described, suitable for capturing them when they are resting on the fronds.
THE MOSAIC DISEASE OF THE HOP; GRAFTING EXPERIMENTS, I
Authors: SALMON E. S. , WARE W. M.
Published: February 2008

Certain hop plants, which were grafted in 1926 with scions either (a) of plants affected with the mosaic disease, or (b) of the seedling variety M 45 (previously proved to be a “carrier”), produced in 1927 shoots affected with mosaic disease.

From the evidence available, it would appear that the virus of mosaic disease can travel down a grafted stem and infect the rootstock.

It would appear, further, that mere contact of a virus‐carrying scion with the stock (with no growth of the former taking place) is sufficient to cause the infection of the rootstock.

When scions of the commercial variety Fuggles were grafted on a hop plant severely affected with the mosaic disease they remained healthy and completed their full seasonal development.
ENGLISH‐GROWN PYRETHRUM AS AN INSECTICIDE. I
Authors: FRYER J. C. F. , TATTERSFIELD F. , GIMINGHAM C. T.
Published: February 2008

The toxicity to Aphis rumicis L. and to certain caterpillars of spray fluids prepared from samples of pyrethrum (Chrysanthemum cinerariaefolium) grown in England from Swiss and Japanese seed have been quantitatively determined.

Pyrethrum flowers, grown in six different localities, showed only slight differences, and, for practical purposes, all the samples had approximately the same toxicity. They did not differ in this respect significantly from a sample grown on the continent.

The toxicities of extracts of equal weights of pyrethrum flowers tested at different stages of development differed very little.

Artificial drying of the flowers had no significant effect on the toxic properties.

The flowers were about ten times as toxic as the stalks, weight for weight.

Prolonged exposure of pyrethrum to wet conditions led to some loss of toxicity, but. contrary to the usual opinion, if stored in a reasonable manner, it remained for long periods without deterioration.

Caterpillars of different species showed marked differences in susceptibility to the action of pyrethrum.

The biological method employed has proved suitable for evaluating samples of pyrethtum.
STUDIES ON OSCINELLA FRIT LINN: OBSERVATIONS ON INFESTATION AND YIELD, SUSCEPTIBILITY TO INFESTATION, RECOVERY POWER, THE INFLUENCE OF VARIETY ON THE RATE OF GROWTH OF THE PRIMARY SHOOT OF THE OAT AND THE REACTION TO MANURIAL TREATMENT
Authors: CUNLIFFE NORMAN
Published: February 2008

The notes collected in the present publication are each concerned with some aspect of the problem of production of varieties of oat plants resistant to the attack of the frit fly.

The quality of a variety may compensate for comparatively heavy infestation.

Data are recorded confirming previous experimentation relating to the susceptibility of the oat shoot to infestation, emphasising its limitation to the early leaf stages.

Experimentation concerned with recovery power after injury showed that different varieties of oats react very differently and indicated the importance of the primary shoot in relation to yield. A few field data are recorded to support this inference.

With common English varieties of oats the influence of variety on the rate of growth of the primary shoot was practically negligible, and therefore observed differences between varieties in extents of infestation of primary shoots cannot be ascribed to variations in rates of growth of primary shoots. The time of tillering did not depart markedly from the mean, but it was not correlated with time of shoot production, so that correlation between extent of infestation of shoot and of grain cannot be expected.

Excess of nitrogenous manure failed to influence the extent of shoot infestation but effected a reduction in the extent of grain infestation during a season when the extent of the attack of the fly was below normal.
SPRAIN OR INTERNAL RUST SPOT OF POTATO
Authors: BURR SYDNEY
Published: February 2008

In the present investigation necrosis of the tubers was found to be due to two distinct diseases: (1) Sprain or Internal Rust Spot, and (2) a disease hitherto unrecorded, which has been named Corky Bacteriosis of the xylem. The former is much the more important and accounts for 98 per cent. of the tissue destruction.

 In Sprain the tissue attacked is the parenchyma both within and without the vascular ring. The lesions vary greatly in form and may consist of spots, arcs, streaks or irregular blotches. The larger lesions are generally hollow in the centre.

 The histological structure of the lesions of Sprain varies slightly according to whether these occur in the starch‐packed cortical tissue or in the pith where the cells are less densely filled with starch, but in either case, is characteristic. A feature of the spots is that they are more or less completely invested with a zone of cork the inner layers of which are suberised.

 The soil on which. Sprain occurs in a virulent form is a light sandy loam deficient in organic matter and one on which potatoes scab severely.

 The disease is apparently slight when the crop is lifted but develops rapidly and continuously during storage.

 Infection of the crop arises mainly from contaminated soil and not from affected seed.

 The causative organism of Sprain has been isolated and typical spots of the disease have been reproduced by inoculation with it. It consists of a very short Bacterium, which, being new to the literature, has been named Bacterium rubefaciens.

 There is little evidence that this organism enters the fully formed tuber through its skin, and isolated spots which have no apparent connection with the peridenn are a feature of the disease. It is suggested that the organisms enter at a very early stage through the stomata or lenticels of the tuber‐bearing stolon, remaining quiescent in the water‐filled intercellular spaces of the tuber and becoming active only when the latter ripens.

 In potatoes affected with Sprain a certain necrosis of the xylem vessels may occur but may easily be overlooked. This Tracheomycosis is essentially different from that of Corky Bacteriosis.

 Corky Bacteriosis produces a browning and lignification of the vascular ring macroscopically resembling the Ring Bacteriosis of B. solanacearum.

 It is essentially a disease of the xylem vessels which thereby become closely invested with a thick layer of suberised cork.

 Corky Bacteriosis is transmitted from the mother tuber to its progeny by way of the stolons. It is also contracted from infected soil apparently by infection of the stolon or the stolon end of the tuber.

 The causative organism of this disease has been isolated and the disease reproduced by inoculation. The organism being new to the literature has been named B. suberfaciens.
THE ACTION OF SULPHUR AS A FUNGICIDE AND AS AN ACARICIDE. PART I
Authors: GOODWIN Wm. , MARTIN H.
Published: February 2008

An examination of the various theories put forward to account for the fungicidal action of sulphur when applied, not to the plant or fungus, but to a heated surface, has been carried out by chemical methods, and it is concluded:

 That, since the volatile agent is capable of passing a glass‐wool filter maintained at the temperature of the heated surface, it is gaseous in character.

 That the removal of the volatile agent by passage through a cooled glass‐wool filter is proof that it is neither sulphur dioxide nor hydrogen sulphide but is elementary sulphur.

 That the condensation of sulphur volatilised from the heated surface appears sufficient to account for the reactions ascribed to particulate sulphur.
THE TURNIP MUD BEETLES (HELOPHORUS RUGOSUS OL. AND HELOPHORUS PORCULUS BEDEL.)
Authors: PETHERBRIDGE F. R.
Published: February 2008

Helophorus rugosus Ol. and Helophorus porculus Bedel, have caused serious damage to late sown white turnips in several cases in the east of England during the last few years.

A case in which the growing points of white turnips (planted out for seed growing) were eaten out by the larvae is recorded.

Swedes and rape are damaged by these pests but not to the same extent as white turnips.

Kale and cabbages are only slightly damaged.

Lettuces were seriously damaged in Surrey in 1924.

One case of an attack on beans by H. rugosus was also noticed. Most of the damage is caused by the larvae which gnaw or tunnel into the “bulb” of the turnip as well as feeding on the developing leaves. The adults also feed on the leaves.

Eggs are probably laid in August and the larvae live from August until April or May.

Pupation takes place in April or May and pupae live about three weeks.

Adults were found from May until the following March.

Descriptions of the larval, pupal and adult stages are given.

Late sowing and frequent cruciferous crops appear to predispose plants to attacks.
THE METAMORPHOSIS AND BIOLOGY OF RHYNCHAENUS ALNI L. (COLEOPTERA)
Authors: OLDHAM JOHN N.
Published: February 2008

The leaf‐mining habits of the species of the genus Rhynchaenus (syn. Orchestes) are well known and Rh. alni L. was found in Warwickshire, England, to be causing a considerable amount of damage to the foliage of elm trees through the mining of the larvae and feeding of the adults. This species is known to attack both Ulmus campestris and Alnus glutinosa, and a historical review of the literature dealing with the beetle has been written in an attempt to elucidate the misunderstandings and settle the controversy concerning the host plant and specific name of the insect.

Brief descriptions of the adult and egg have been given. The first stage larva, which differs from later stages, has been shortly described, while a note has been added on the intermediate stages. The external morphology of the full‐grown larva and of the pupa has been described in detail.

The insect has but one generation in the year, in the Warwickshire area, and the life history and general biology have been discussed.

During the investigations it was observed that a considerable number of hymenopterous parasites were attacking this insect. From material gathered, eight distinct species of parasites have been reared, and identified from Rh. alni L. of which seven belong to the Chalcidoidea and one to the Ichneumonoidea.
STUDIES OF WOOD‐DESTROYING FUNGI I. POLYPOBUS HISPIDUS (FRIES)
Authors: NUTMAN F. J.
Published: February 2008

The characteristics of the Polyporus Msjndus, when grown on artificial media, both solid and liquid, are described and compared with those given by Baxter.

Growth on wood of ash under laboratory conditions produces a rot which is indistinguishable from that occurring naturally. The distribution of the hyphae in the wood is described.

The mode of penetration of the cell‐wall by the hyphae is figured. It is apparently by pits in the early stages of decay, but by bore‐holes, formed entirely by enzyme activity, in‐the more advanced rot.

The rate of growth of the fungus under controlled conditions has been measured, and shown to be 0–5 cm. per month.

Successful inoculation experiments have been carried out with young trees, confirming the results of Baxter, who states that the fungus can attack young, living sap wood.

An investigation of the enzymes produced by the mycelium has been carried out, and a method evolved for demonstrating the presence of a ligninase. This is a modification of Czapek's “hadromal” reaction.

The following enzymes are shown to be present in the mycelium: emulsin, diastase, invertase, ligninase, hemicellulase, oxidase, and catalase. The list is not intended to be exhaustive.

The writer desires to express his thanks to Mr W. R. Day, of the Imperial Forestry Institute, Oxford, and to Dr W. Brown, of the Royal College of Science, for helpful criticism and advice. Also to Mr R. S. Pearson, C.I.E., F.L.S., the Director of Forest Products Research, for permission to publish this paper.
THE CONTROL OF “BUNT” IN WHEAT
Authors: WESTON W. A. R. DILLON
Published: February 2008

Results of control experiments over a period of four years are given. The wet treatment, with formaldehyde and copper sulphate, are compared with the dry treatment, using copper carbonate.

The dusting method is discussed. It is shown that infection varies directly with the spore load and that the efficiency of the dusting treatment is proportional to the rate of contamination. For the usually slightly contaminated seed samples this treatment has been effective in controlling bunt.

The practical aspect of dusting wheat is discussed and its cost compared with the other treatments.

A report is given of the feeding of dressed wheat to poultry.
The Action Of Sulphur As A Fungicide And As An Acaricide
Authors: GOODWIN WM. , MARTIN H.
Published: February 2008

The conclusion arrived at by chemical methods, that the volatile agent produced when sulphur is applied to a heated surface is gaseous sulphur, has been subjected to biological tests in which the fungi Ery‐siphe graminis and Sphaerotheca Humulind the gall mite Eriophyes ribis were employed.

The fungi were found not to be sufficiently sensitive to yield satisfactory and concordant results and strong support is given to the view that actual contact of the sulphur particle with the fungus is necessary before fungicidal action can occur.

It was shown that the agent present in air passed over heated sulphur and responsible for the death of the gall mite was not removed by filtration through a heated glass‐wool plug, this observation being contrary to the view that the toxic agent is produced initially in solid form.

Filtration through a cooled glass‐wool plug only removed part of the volatile agent and it was shown that the gall mite is affected by the traces of sulphur volatilised at ordinary temperatures.

The results of the experiments with the gall mite were in complete accord with those obtained in the previous chemical work.

At relatively large concentrations sulphur dioxide and hydrogen sulphide are without permanent effect upon the gall mite and these gases are therefore not responsible for the acaricidal action of sulphur.
THE INFLUENCE OF BRIGHT SUNSHINE UPON THE TOMATO UNDER GLASS
Authors: BEWLEY W. F.
Published: February 2008

The tomato crop produced in glasshouses is affected by prevahg weather conditions.

The yield per acre varies directly in relation to the total hours of bright sunshine during the period April 1st t o September 30th.

Total sunshine also affects the potash requirement of the tomato, less potash being required during bright sunny weather than under dull conditions.
SOME PROPERTIES OF THE CELL‐WALL OF COTTON‐HAIRS
Authors: BARRITT By N. W.
Published: February 2008

The cell‐wall of the living cotton‐hair is under tension and its diameter is unaffected by osmotic pressure or the death of the cell.

Increase of diameter of the uncollapsed hair by swelling in caustic soda varies inversely as the diameter of the hair in the case of fine cottons, and does not occur with coarse cottons.

The diameter of the uncollapsed cotton‐hair varies inversely as the intrinsic strength of the collapsed hair.

I have to thank Dr R. H. Pickard, F.R.S., and his colleagues Miss Calvert, M.Sc, and Miss Clegg, M.Sc, of the Shirley Institute, Manchester, for their very helpful criticisms.
CARBON DIOXIDE PRODUCTION IN SANDS AND SOILS IN THE PRESENCE AND ABSENCE OF AMOEBAE
Authors: CUTLER By D. WARD , CRUMP L: M.
Published: February 2008

Experiments are described on carbon dioxide production from soil and sand cultures containing a species of bacterium with and without amoebae. The following results were obtained:

Carbon dioxide production and bacterial numbers are correlated provided that amoebae are not present, or are present in very small numbers.

The bacteria are more efficient as producers of carbon dioxide when their numbers are not rising and less efficient when their numbers are increasing. This does not hold for young cultures. Also each bacterium becomes less efficient as the density of the population increases.

The amoebae cause a decrease in carbon dioxide production in sands containing peptone, but an increase in sands containing mineral salt solution with glucose or soil extract
OBSERVATIONS DURING 1927–28 ON THE INCIDENCE OF “RUSTS” ON VARIOUS SELECTED WHEAT VARIETIES, WITH SPECIAL REFERENCE TO THE INTENSITY OF YELLOW RUST, PUCCINI A GLUM ARUM, ERIKS. AND HENN.
Authors: WESTON W. A. R. DILLON
Published: February 2008

Observations on the incidence of yellow, brown and black rust on selected wheat varieties are recorded.

The intensity of yellow rust on these varieties is given.

It is shown that bunt increases the susceptibility of varieties to yellow rust.

It is suggested that in testing wheat varieties for resistance to P. glumarum the seed should be previously bunted, and that if no yellow rust then appears that the variety should be regarded as truly resistant.

It is suggested that a generalisation cannot be made that the 28 chromosome group is more resistant to pathogens than the 42 chromosome group, and also that there is no firm foundation for believing that the species and varieties of wheat which are resistant to rust are resistant to bunt and wee versa.

In concluding these observations the writer expresses his thanks to Dr E. F. Gaines, Pullman, Washington, Prof. E. C. Stakman, St Paul, Minnesota, and Dr Mains, Perdue University, Indiana, for supplying him with a number of American wheat varieties, also to Mr F. T. Brooks, Cambridge, for his valued criticism.
TREATMENT OF SUGAR BEET “SEED” TO PREVENT SEEDLING DISEASES
Authors: WOODWAED B. C. , WESTON W. A. E. DILLON
Published: February 2008

The organisms responsible for Blackleg in sugar beet seedlings have been referred to and the damage that they do considered.

It has been shown that treatments used to disinfect the “seed” may be harmful, they may exert no influence, or they may be of considerable value.

The present trials have shown the beneficent effects of an organic compound containing mercury. This material increased the “plant” in the majority of cases, and this increase varied between 12 per cent, under some conditions and in increasing amounts up to 193 per cent, under more favourable conditions.

An increase in the vigour of young plants was noted occasionally. Quantitative tests showed an increase in both the green and dry weight per seedling as the result of treatment. The beneficial action of treatment is not due to the influence of water.

The organic compound containing mercury was the most effective in reducing diseased growths during laboratory tests; the proprietary dust was nearly as efficient. Steeping in a f per cent, solution of carbolic for half‐an‐hour was ineffective.

Treatment of the clusters with 60 per cent, sulphuric acid did not appreciably improve “plant” establishment, but this treatment followed by the mercury treatment increased the number of plants considerably.

Field trials conducted for one season on a field scale have not shown an increase in the percentage of sugar as a result of the treatment of “seed,” but a slight increase in yield and in the total number of roots per acre was noted as the result of treatment with the organic compound containing mercury. The proprietary dust was not noted as being responsible for reducing the “plant” in the field. Its beneficent action was not as uniformly apparent as that of the mercury material.

Carbolic acid at a strength of per cent, was definitely injurious when used for steeping purposes. Furthermore, trials show no benefit from a modified form of this treatment in which a 3| per cent, solution is sprinkled on the “seed.” Other materials tested were found to be of doubtful value.

Certain samples of commercial “seed” as supplied treated with a mercury material were found to be infected to a considerable extent by Phoma Betae. Such “seed” it was found could be efficiently re‐disinfected by careful re‐treatment with marked beneficial results.

In conclusion it is desired to thank those who gave assistance. Among these are Mr Alfred Eastham, Director of the Official Seed Testing Station, Cambridge, Dr Van Poeteren, Wageningen, Mr G. R. Clarke, Advisory Chemist, and Dr N. Cunliffe, Advisory Entomologist both of Oxford, Mr W. A. Stewart and Mr W. R. Seward, Dr Pethybridge and the officials of many beet sugar factories who lent a helping hand.
STUDIES IN BACTEBJOSIS. XVI:THE AGGLUTINATING AND PLASMOLYTIC ACTION OF THE SAP OF THE POTATO ON VARIOUS PARASITIC AND SAPROPHYTIC SPECIES OP BACTERIA
Authors: BERRIDGE EMILY M.
Published: February 2008

The fresh juice of potato is shown to possess agglutinating action on certain bacteria, and strong plasmolytic power which is gradually lost on exposure to the air.

The agglutinating power is found to be due to substances which are precipitated from the potato juice by 95 per cent, alcohol, and is independent of any previous inoculation of the potato with bacteria.

At the natural H‐ion concentration of the potato sap the precipitate solution agglutinates and plasmolyses non‐pathogenic species to potato in varying degrees, but the pathogenic species tested were unaffected by it.

The agglutinating power of the potato precipitate for any one species varies with the H‐ion concentration of the solution; each species remains unagglutinated and unplasmolysed at one definite H‐ion concentration.

This point of non‐agglutination at which the species appears to be least affected by the potato precipitate, was found to be approximately the H‐ion concentration of the sap of the potato itself, i.e. about pH. 6‐2, in the case of the two species causing soft rot in the potato. The twelve species non‐pathogenic to potato which were tested have non‐agglutination points above or below this.

The precipitate has a plasmolytic as well as an agglutinating action on any species at pH. values more acid than its point of non‐agglutination; this has been shown by cultural experiments to be probably dependent on the presence of phosphates in the precipitate.

The agglutinating power may possibly be due to traces of salts of di‐ and tri‐valent metals in the precipitate.

The writer wishes to record her indebtedness to Prof. V. H. Blackman and to Dr S. G. Paine for the laboratory facilities accorded her, and for helpful interest and criticism in the preparation of this paper. Especially her thanks are due to Dr Paine for the two photographs illustrating agglutination.
THE MORPHOLOGY AND PHYSIOLOGY OF TWO LACTOSE‐FERMENTING YEASTS AND CHEMICAL CHANGES DURING THE RIPENING OF CHEESE FROM MILK CONTAINING THEM
Authors: ALLEN L. A. , THOENLEY B. D.
Published: February 2008

Two lactose‐fermenting yeasts isolated from cheese have been described and though markedly similar in many respects they have been referred to separate species, the one being a Torula whose close relationship could not be definitely established, and the other being a true yeast believed to be correctly identified with Zygosaceharomyces lactis (Dombrowski).

The two yeasts have been found to have an appreciable proteolytic effect on the casein of milk after several weeks. The effect of one of the yeasts alone and of the yeast plus Streptococcus lacticus on the lactose of milk has also been studied.

Cheddar cheese inoculated with the yeasts has been found to differ considerably in quality and texture from the control cheese. A comparative study of the extent of protein degradation in two ripe cheeses, one inoculated with the Torula and one control, has shown the proteolytic effect of the yeast in the course of ripening.

The authors wish to express their thanks to Dr S. G. Paine for his constant interest and help in this work, and to Mr A. T. R. Mattick for many valuable suggestions.
INVESTIGATIONS ON HETERODERA SCHACHTII, SCHMIDT. IN LANCASHIRE AND CHESHIRE
Authors: SMITH A. M. , MILES HERBERT W.
Published: February 2008

Data concerning infestation of H. schachtii, certain soil properties and crop yield, from a series of plots at four centres affected with disease, have been collected and examined.

Limitations imposed on the design of the plots have prevented a complete analysis of the variates, but the results obtained lead to the conclusion that eelworm infestation is not of primary importance in determining the yield of potatoes and that the cysts tend to increase in number only on a crop which is not a failure but which has been adversely influenced by some other factor.

The authors would like to express their thanks to Messrs I. S. Macdonald, J. Orr, B. Holmes Smith and I. Thomas of the Advisory Department at Manchester for their willing co‐operation and assistance, and to Mr L. H. C. Tippett for his helpful criticism of the statistical treatment of the results.
STREAK—A VIRUS DISEASE OF TOMATOES
Authors: JARRETT PHYLLIS H.
Published: February 2008

Summary.

A comparison of streak disease of tomatoes, derived from commercial glasshouses, and experimental streak produced by combined inoculation of the viruses of potato mosaic and tobacco mosaic, is given in detail.

The characters employed in comparison are the host range of each virus and its resistance to various temperatures, to different concentrations of alcohol, and to ageing in vitro.

Glasshouse streak and tobacco mosaic show an equal resistance to alcohol, heat and ageing in vitro, and have, in addition, an identical host range. Treatment for 1 hour with 90 per cent, alcohol and for 10 minutes at 850 C. did not destroy the infectivity of either of these viruses.

Glasshouse streak is shown not to contain the virus of potato mosaic, but is of itself able to produce necrosis in tomatoes without the participation of potato mosaic. The factors underlying this have not been determined.

It is concluded that tobacco mosaic and the mosaic of glasshouse streak are probably identical, and that much of the streak occurring in glasshouses is due to a single virus, and not a mixed infection of this with potato mosaic.
THE “MATURATION PERIOD” OF THE TOMATO PLANT
Authors: BEWLEY W. F. , CORBETT W.
Published: February 2008

Summary.

The period between the opening of a tomato flower and the picking of the fruit which develops from it has been termed the maturation period.

Usually, the maturation periods of the different fruits produced by a tomato plant vary considerably.

The maturation period lengthens as the plant ages, and as the truss lengthens.

The graph of the maturation periods of the fruits produced by a tomato plant approaches a straight line as the efficiency of the plant increases.
STUDIES IN BACTERIOSIS.
Authors: BERRIDGE EMILY M.
Published: February 2008

Summary.

The H‐ion concentration of plant sap most favourable to the growth of B. tumefaciens has been shown in a previous paper to be about pH. 5‐2. This H‐ion concentration characterises meristematic tissue where tumours due to B. tumefaciens originate.

The bacterial zoogloea present within and on the surface of the tumours gives the red colour with methyl red which indicates approximately the same value, pH. 5‐2.

The cell wall in contact with the bacterial zoogloea appears to be suberised; and it is suggested that the process of tumour formation is due to healing reactions similar to those which take place in wounded plant tissue.
THE SOIL FUNGI OF THE DOVEY SALT MARSHES
Authors: ELLIOTT JESSIE S. BAYLISS
Published: February 2008

Summary.

In this investigation of the fungi of the soil of the Dovey Salt Marshes (Ynyslas) 48 fungi were isolated.

Twelve of the species found do not appear to have been recorded before for the British Isles.

The area investigated is a badly aerated, stiff, tenacious clay, alkaline in reaction (pH 8), with a high water content, due mainly to periodical inundations by tidal salt water.

Method of investigation consisted in taking samples of soil from a depth of 11/2 and 31/2 inches and either planting portions of this directly on to specially prepared media, or first shaking up a portion in water and then inoculating the prepared media with some of the suspension.

Three fungi–Torula allii, Penicillium hyphomycetis and Fusarium oxysporium var. resupinatum—were almost invariably present in every sample of soil: almost equally common were Trichoderma lignorum, T. Köningi, Hormodendron cladosporoides, Mucor circinelloides and Periconia felina.

Most of the fungi found are species found above ground as saprophytes, and may have been introduced into the soil by drainage, etc.

The writer considers fungi are active only in association with organic material.

The vegetation covering this marsh shows marked zonation: soil samples were chiefly taken from the Glycerietum and Aimerietum.

The same species of fungi were common to the two associations.

Glyceria maritima is a most effective silt binder, because the stele of its rhizomes and roots consists almost entirely of lignified tissue which does not yield to the activities of the soil fungi; Armeria maritima is not so effective a silt binder because the stele of its rhizomes and roots contains very little lignified tissue—at a depth of a foot, the tap roots of Armeria are little more than hollow tubes, the interiors having been removed by fungi and bacteria.
ON THE BIOLOGY OF THE GALL‐MIDGES (CECIDOMYIDAE) ATTACKING MEADOW FOXTAIL GRASS (ALOPECURUS PRATENSIS), INCLUDING THE DESCRIPTION OF ONE NEW SPECIES
Authors: BARNES H. F.
Published: February 2008

Summary.

Three midges do serious damage to the seeding of meadow foxtail grass; they are Dasyneura alopecuri (Reuter), Stenodiphsis geniculati Reuter and Contarinia merceri n.sp. All three occur almost wherever the grass is grown.

The distribution and bionomics of these midges are dealt with; D. alopecuri has one brood a year, S. geniculati has two, while C. merceri usually has one but occasionally may have two.

“Blindness” or empty husks in meadow foxtail grass is due very largely to attacks of C. merceri, which midge does the most extended damage.

Keys are given for the separation of larvae, pupae and adults.

Control measures are discussed and a method of keeping sheep on the grass until a certain safety date, i.e. a date when the crest of emergence of the female midges is over, is strongly advocated in districts where the bionomics is known.
A BOTANICAL STUDY OF PASTURE PLOTS
Authors: FENTON E. WYLLIE
Published: February 2008

Summary.

The best seeds mixtures were of the Cockle Park type.

In the initial stages, good soil tilth and freedom from weeds may out‐weigh certain disadvantages in the formation of a pasture.

The shelter afforded by the quick germination and growth of Italian Rye Grass is very important in areas affected by summer drought. Soil moisture is conserved and slower developing seeds show an increased germination and growth.

In the later phases of turf formation, Wild White Clover takes the place of Italian Rye in conserving surface moisture:

The passing of Red Clover and decrease of Rye Grasses must be compensated for by the growth and spread of Cocksfoot, Wild White Clover, Rough Stalked Meadow Grass and other grasses.

The plots showed three phases in vegetation before a more stable flora was developed.

The order of aggressiveness in the plots was: Italian Rye, Perennial Rye, Red Clover, next Cocksfoot followed by Wild White Clover, Bent and Rough Stalked Meadow Grass, then Timothy, Tall and Meadow Fescue.

Burnet is too aggressive; Chicory is not so aggressive, is more palatable and quite as resistant to drought.

Cocksfoot, Fescues and Wild White Clover are good drought resisters when once established.

Tall and Meadow Fescues are depressed chiefly by Rye Grasses. In the plots studied, the late appearance of Fescues was due to delayed germination.

Alsike Clover was a failure, and Timothy was not a success.

A high seeding of Red Clover, or mixtures of Broad Red and Late Flowering Red Clovers are not always successful.

Frequent or continuous cutting and removal of vegetation depresses growth in the following year.

Lack of rolling or treading in small plots is a source of experimental error.

The weed flora of the Pasture plots was small and in marked contrast to the Hay plots.

In spite of initial differences, under similar treatment there is soon a marked tendency to develop a flora of the same proportions in all plots.

Altering a seeds mixture suitable for a long ley or permanent pasture so as to obtain a heavy Hay cut from the early growth is unsound. It endangers turf formation, encourages inferior grasses and weeds, and depresses the useful plants.
STUDIES ON OSCINELLA FRIT LINN.
Authors: CUNLIFFE NORMAN
Published: February 2008

Summary.

Data, collected in Sweden during the year 1927, indicate the existence of considerable variation in extent of infestation of the grain of different varieties, sown at the same time. Also they suggest that sterility or “blindness” of grain may be a varietal character.
BACTERIAL DISEASES OF STONE‐FRUIT TREES IN BRITAIN
Authors: WORMALD H.
Published: February 2008

Summary.

A bacterial shoot wilt, observed at the East Malling Research Station in 1923 and 1924, is described.

A bacterium isolated from infected shoots has been shown by inoculation experiments to be the cause of the disease.

The organism not only infects young green shoots, but experiments have shown that it can also cause leaf spots, and that it can induce gummosis and cankers on woody branches and on stems.

Cultural studies of the organism suggest that it has not previously been described, so the name Ps. prunicola is proposed for it.
THE BIOLOGY OF THYSANOPTERA WITH REFERENCE TO THE COTTON PLANT
Authors: MacDILL ELSIE I.
Published: February 2008

Summary.

Investigations were made of the degree of infestation of plants grown in light soil and in clay soil sown at different dates. The plants sown late in the season in light soil were more affected by the thrips, the infestation being relatively high almost from the germination of the plant and causing death before the flowering stage was reached. On the blocks of plants in light soil sown earlier in the year the infestation was relatively low for a considerable period, and although, at the end of the season, the thrips became very numerous on these plants it was not until after the bolls had been formed, and in this case the practical damage was small.

The plants sown in clay soil at different dates did not show such a marked difference in the degree of infestation, and all were less infested by the insects than the corresponding blocks of plants in light soil. This corroborates the findings of previous experiments, namely, that plants grown in light soil are found to be more heavily infested by T. tabaci than plants grown under similar conditions in clay soil.

I should like to take this opportunity of thanking Prof. Dunkerly for his helpful criticism, Miss R. M. Smith and Mr I. Thomas for their assistance in making the counts, and Mr R. Stewart for his analysis of the soils used.
THE PASTURE PROBLEM IN AREAS OF PERIODIC DROUGHT
Authors: NELSON ALEXANDER
Published: February 2008

Summary.

The paper deals with areas under the Mediterranean type of climate where periods of moisture supply and lower temperature with lowered evaporation alternate annually with periods of low moisture supply and higher temperature with increased evaporation.

The suggestion is made that in such areas where no system of economic production has already been evolved permanent pasture formation for stock production on a system of extensive husbandry would be economic.

That permanent pasture could be produced economically by a plant association capable of regenerating itself annually after the drought stress period owing to the production of a large number of seeds by its individual members.

That the stock carried by such a pasture during its production period could be carried over the alternating drought period of low or nil production by a self‐perpetuating grain crop along the lines adopted in West Australia using the lupin.

Various difficulties and amendments of the system proposed are mentioned and discussed.
THE BIOLOGY OF THYSANOPTERA, WITH REFERENCE TO THE COTTON PLANT
Authors: MacGILL ELSIE I.
Published: February 2008

Summary

In several previous papers on Thysanoptera it has been shown that the condition or type of soil may have some influence on the infestation of a plant by thrips.

Experiments were carried out to determine the effect of different types of soil on the infestation of the cotton plant by Thrips tabaci.

The types of soil used in the experiments were a heavy clay soil and a light soil with less than 15 per cent, of clay, about fifty pots being filled with each type.

Each block of fifty plants was divided into two and the soil in one half was tilled while in the other it was left undisturbed.

It was found that the plants in the block with unfilled clay soil were least infested by T. tabaci, while the plants in the block with light, tilled soil were the most highly infested.

The average infestation of the two blocks with light soil was slightly higher than the average infestation of the clay soil blocks, in spite of the fact that at the beginning of the season the former blocks of plants and the thrips on them suffered severely from a sudden great rise in temperature.

In both types of soil the block with tilled soil was more highly infested than the other block.

It appears from these experiments that light soil is more favourable to the multiplication of soil pupating species of thrips than an easily eaking, clay soil and that tilling the soil increases the infestation by these insects.
Aphides As Vectors Of “Breaking” In Tulips
Authors: Hughes. A. W. MoKenny
Published: February 2008

Summary.

1. Myzus persicae Sulz is a vector of “breaking” in tulips.

2. Macrosiphum gei Koch is also a vector of “breaking” in a lesser degree.

3. “Red break” and “white break” are transmitted equally by the two species.

4. It is suggested that “red break” is an earlier stage in the development of the virus and that “white break” is the final stage.

5. There is at present no indication that “parrot” is transmissible by these two aphid species, though no conclusion can be reached in one season.

6. There is some indication that the virus can be transmitted from some varieties of tulips more readily than from others.

7. Mass infection in the open gave a lower percentage of “break” khan individual infection under glasshouse conditions.

8. No conclusive evidence has been obtained to show that Anuraphis tulipae B. de Fonse and Rhopalosiphoninus tulipaella Theo. convey “breaking,” but in any case they cannot be considered as important vectors.