bluuebunny/crossref_metadata_2025 huggingface dataset:
THE HABITS OF THE GLASSHOUSE TOMATO MOTH, HADENA (FOLIA) OLERACEA, AND ITS CONTROL.
Authors: LLOYD Ll.
Published: February 2008

H. oleracea is not a normal pest of tomatoes grown under glass, and where it has become established as such it is still in some respects ill adapted to a greenhouse life on a tomato diet. The larvae eat the fruit because many of them are unable to survive on the foliage alone. In spite of this weakness, it has become a serious pest because the species is a prolific one and, once having entered a greenhouse, it usually becomes a prisoner there. In a normal year there are two complete generations and a partial third, and the moths are present in the houses continuously from February to October.

Spraying the young plants with arsenate of lead largely controls the first brood of larvae, but not entirely, because moths of the first flight of the year are still emerging when it is not practicable to use a poisonous spray on the plants. The plants should be sprayed three times when the larvae appear early: (1) when the seedlings are in pots; (2) just after planting out; (3) about a month before fruit picking begins. The last operation is the most important and the two previous ones may be omitted if there are no signs of larvae feeding.

Systematic moth trapping must be done throughout the growing season, because it will reduce the numbers of moths which pass out of the houses, and these, or their offspring blunder into the same or neighbouring greenhouses; and also because it is the most effective form of control when spraying is not practicable, and will reduce the infestation to a very great extent. Sixty jars baited with ale, treacle and 1 per cent, sodium fluoride should be used to each acre of glass. The dead moths should be removed frequently, and the jars should be rebaited every third week.

Broken fruit must not be allowed to lie about in the houses as the moths feed on this and become more prolific.

Many full grown larvae may be trapped in sacks placed about the houses. The sacks should be collected and dipped in boiling water every third week.

Pupae should be destroyed in the winter.

Special baskets should be kept for fruit picking, and those from the markets should never be allowed in the houses.

The pest spreads rapidly through areas where the nurseries are congested owing to the escape of moths from the infested houses. It may be introduced into isolated localities by means of market baskets, or by plants purchased from infested nurseries. On its first appearance every method of control should be applied at once, as attempts to check it by picking off the larvae by hand in trade nurseries have almost invariably ended in failure.
A QUANTITATIVE ANALYSIS OF PLANT GROWTH: PART I.
Authors: BRIGGS G. E. , KIDD FRANKLIN , WEST CYRIL
Published: February 2008

The series of articles of which this is the first instalment, constitutes an attempt to formulate methods for the quantitative analysis of plant growth and to apply these methods to data which have been lying dormant in the literature for 40 years.

In the present chapter the relative growth‐rate curve, which is the weekly percentage increase in dry‐weight plotted against time, and also the leaf‐area ratio curve, that is, the leaf‐area in sq. cms. per g. plotted against time, have been employed. And as a typical example of an annual plant maize has been selected since data are given by Kreusler for this plant grown in four successive years.

The first noteworthy result of this analysis is the demonstration of the fact that the growth‐rate varies greatly in magnitude at different periods in the life‐cycle of a plant such as maize in a perfectly definite manner.

Fig. 9 gives the generalised form of the growth‐rate curve for maize throughout its life‐cycle. Although the broad form is that of a Sach's grand period curve, it must be noted that it is not a grand period curve, since the grand period curve as denned by Sachs is the curve of the actual increment per unit of time plotted against time and not of relative increment, that is, increment per unit of matter per unit of time plotted against time. On the broad form of the relative growth‐rate curve for maize are superposed three secondary features, an initial fall, and two subsidiary maxima on the descending limb.

In this generalised curve the initial period A‐B is the period before the assimilatory organs are able to counterbalance the loss in dry‐weight due to respiration, and the rate of growth is consequently negative or nil. The phase B‐C corresponds to a phase in morphological development during which the leaf‐area per unit dry‐weight increases to a maximum. The phase C‐F covers the remainder of the life‐cycle of the plant during which the leaf‐area per unit dry‐weight is continuously decreasing. The subsidiary maxima D and E coincide with the time of the record of the appearance of the male and female flowers respectively. The minima X, Y which precede these maxima, correspond with the earliest stages of flower development, and are possibly due to increased respiration during that period.

The incidence of the maxima is controlled by environmental conditions—not by the environmental conditions operating at the time, but by those obtaining at some previous stage in the life‐history of the plant.

The fact that the curve for leaf‐area per unit dry‐weight throughout the season (which has been calculated) shows a correspondence with the growth‐rate curve indicates that the physiological basis for increased and decreased relative rate of growth is a corresponding change in the assimilating area per unit dry‐weight. This point will be dealt with in the next chapter.

Evidence from the quantitative analysis of plant growth for maize indicates that the seedling leaves do not perform their normal assimilatory function till some time after their appearance.
ON THE OCCURRENCE IN BRITAIN OF THE CONI‐DIAL STAGE OF SCLEROTINIA MESPILI SCHELL
Authors: WORMALD H.
Published: February 2008

This article records the occurrence, in the spring of 1920, of the conidial form of Sclerotinia Mespili Schell. on the leaves of medlar trees in four localities in Kent and one in Somersetshire.

Mycelium obtained from dead flowers which had remained on the tree from the previous year gave rise to cultures similar to those obtained from conidia taken from infected leaves but the Sclerotinia stage of the fungus was not observed.
A QUANTITATIVE ANALYSIS OF PLANT GROWTH: PART II.
Authors: BRIGGS G. E. , KIDD FRANKLIN , WEST CYRIL
Published: February 2008

In this chapter we have continued our analysis of the results of the experiments on the growth of maize carried out by Kreusler and his co‐workers. The rate of growth has been expressed per unit leaf‐area instead of per unit dry‐weight as in the last chapter. The term “Unit Leaf Rate” is used for the weekly rate of increase of dry‐weight in mgs. per sq. cm. The Unit Leaf Rate, instead of undergoing a perfectly definite type of variation, as does the Relative Growth Rate, fluctuates about a mean value. The larger fluctuations which occur in the values for Unit Leaf Rate calculated for the later phases of the life‐cycle have been attributed mainly to sampling errors.

Correlations between Unit Leaf Rate and various environmental factors have been determined.

The general evidence is that the Unit Leaf Rate is correlated more closely with temperature than with any of the other environmental factors.

By allowing for respiration on the basis of our own experimental results values for the real assimilation were arrived at. These also show a closer correlation with temperature than with light.

The values for assimilation determined from the Unit Leaf Rate are of a lower order than those determined by the “half‐leaf” method, but much higher than those determined by the “gasometric” method.

Finally, the authors wish to express their indebtedness to Dr F. F. Blackmail for his stimulating criticism and help in this and in the previous chapter.
ON FORMS OF THE HOP (HUMULUS LUPULUS L. AND H. AMERICANUS NUTT.) RESISTANT TO MILDEW (APHAEROTHECA HUMULI (DC.) BURR.). IV
Authors: SALMON E. S.
Published: February 2008

Several forms of H. Lupulus with yellowish‐green (“golden”) leaves exist. One form (T) has proved persistently immune to mildew both in the greenhouse and in the open. A second form (9) has proved slightly susceptible when grown in the greenhouse. A third form (3) is susceptible in the greenhouse and in the open. This ♂ form appears to be the one found originally in Germany and described under the name of H. Lupulus aureus. No account of the origin of any ♀“Golden hop” hag been found in horticultural literature.

Certain seedlings raised from the immune ♀“Golden hop” (the ♂ parent being unknown) possess green leaves and are immune to mildew when grown in the greenhouse.

Different seedlings of the wild hop (H. Lupulus) have distinctive physiological or “constitutional” characters, which are constant under the same environment. These characters confer immunity or susceptibility, or intermediate grades of susceptibility, on the respective seedlings. The immunity is retained by the plant after four years' residence in the manured soil of the hop‐garden.

Certain seedlings of the wild hop which show persistent immunity when grown in the greenhouse show some degree of susceptibility when grown in the open. The susceptibility shown is usually very slight. There is some evidence that this breaking down of immunity is due to the effect of certain climatic conditions.

In the great majority of cases, the greenhouse conditions do not have the effect of making seedlings of the wild hop immune to mildew. In the case of some seedlings extreme susceptibility is shown under greenhouse conditions.

The phenomenon of semi‐immunity is shown by certain seedlings of various origins.

A form (8) of H. americanus Nutt., obtained from the United States, has proved immune to mildew under greenhouse conditions. Under the same conditions several American cultivated varieties proved susceptible.
STUDIES IN BACTERIOSIS. V: FURTHER INVESTIGATION OF A SUGGESTED BACTERIOLYTIC ACTION IN PROTEA CYNAROÏDES AFFECTED WITH THE LEAF‐SPOT DISEASE
Authors: PAINE SYDNEY G. , BERRIDGE EMILY M.
Published: February 2008

Summary

The production by the cells of Protea cynaroídes of a bacteriolysin against the organism which produces a leaf‐spot disease, suggested in a former paper, has not been confirmed.

The bacteria enter the leaf by way of the stomata; the local lesions produced are prevented from spreading by the development of wound cork.

The causal organism succumbs very readily to the desiccation to which it is subjected owing to the cells which it attacks being cut off by the wound cork from their water supply.
PRELIMINARY OBSERVATIONS ON THE HABITS OF OSCINELLA FRIT, LINN.1
Authors: CUNLIFFE NORMAN
Published: February 2008

The adult frit‐fly is prevalent in the field throughout the year except for the period November to April.

There are periods of high prevalence, which are probably limited by meteorological conditions.

High prevalence seems to be associated with high temperatures and emergence with rainfall, and should not be associated with any particular brood or generation.

It is very probable that normally four generations are produced in one year and that the fly is double‐brooded.

The periods between the emergence of successive generations are about 50 days in spring, 35 days in summer and 230–250 days in winter.

Arrhenatherum avenaceum, Festuca pratensis, Lolium italicum, Lolium perenne and Poa annua can be utilised as host plants in the summer and Alopecurus myosuroides, Arrhenatherum avenaceum, Hordeum pratense, Lolium italicum and perenne in the winter.

In captivity, the longevity of the imago averages 50 days in spring and in summer.

Ploughing‐in and rolling would only control the pest on heavy land.

Nitrogenous manures are not likely to repay the cost of application on average land in England.

The following Hymenopterous parasites are recorded, for the first time, as attacking frit‐fly: Chasmodon apterus, Nees, Psichaera (Först.) spp., Aphidius granarius and Dicyclus fuscicornis, Walker.
STUDIES ON THE APPLE CANKER FUNGUS
Authors: WILTSHIRE S. P.
Published: February 2008

The infection of the apple stem by the canker fungus through the leaf scare is described.

The fungus appears to enter through small cracks which appear in the leaf scar tissues, in the autumn immediately after defoliation and in the spring when the buds are swelling.

The possibility of preventing this infection by disinfecting the leaf scare by fungicides is discussed and results of preliminary trials recorded.
BIONOMICS OF WEEVILS OF THE GENUS SITONA INJURIOUS TO LEGUMINOUS CROPS IN BRITAIN1
Authors: JACKSON DOROTHY J. , SITONA HISPIDULA F. , THUN S. SULCIFRONS , HERBST S. CRINITA
Published: February 2008

1.Sitona hispidula is common throughout Great Britain upon clover and lucerne.

The adults eat the leaves and the larvae damage the roots.

Sitona sulcifrons is frequently abundant upon “seeds” clover and the larvae feed upon the root nodules.

Sitona crinila frequents tares, clover, lucerne, etc., but is rarely sufficiently common to cause injury.

The adults of S. hispidula are either fully‐winged or brachypterous and two forms of brachypterous wings have been observed in S. sulcifrons.

The life‐history of these three species has been investigated in Britain for the first time.

There is only one generation in the year.

The adults live 12 months.

The period of oviposition and the length of the egg, larval and pupal stages varies according to the species.

The Braconids Perilitus rutilus Nees, P. cerealium Hal., P. aethiops Nees, Pygostolus falcalus Nees and a species of Liophron are recorded for the first time as parasites of the adult beetles.

The fungus Botrytis bassiana (Balsamo) Montagne attacks these species of Sitona.
THE TOXIC ACTION OF TRACES OF COAL GAS UPON PLANTS
Authors: PRIESTLEY J. H.
Published: February 2008

1. There is clear evidence in the literature that the toxic action of traces of illuminating gas upon plants may be traced to the presence of gaseous unsaturated hydrocarbons. A concentration of one part of ethylene in ten million of air is toxic to the etiolated epicotyl of a pea.

The effect of these unsaturated hydrocarbons can be traced in the case of root or etiolated stem to their inhibition of the formation of a functional primary endodermis, which is usually present in these plant structures.

The unsaturated hydrocarbons prevent the formation of a functional endodermis, by preventing the normal accumulations of unsaturated acids in the region of the future Casparian strip.

It is suggested that the effect of traces of these gaseous unsaturated hydrocarbons upon cork formation may be due to the arrest of the normal deposit of fatty acids in the membranes of the cork cells.

The practical significance of this work lies in the fact that definite diagnostic features may now be sought for when injuries to plants are suspected to be due to gas poisoning.
STUDIES ON THE APPLE CANKER FUNGUS II. CANKER INFECTION OF APPLE TREES THROUGH SCAB WOUNDS1
Authors: WILTSHIRE S. P.
Published: February 2008

The infection of apple trees by the canker fungus through scab infections is described.

The conidia alighting on the exposed scab stroma give rise to a mycelium which attacks the latter and then grows out into the cortex. The fungus is able to pass through any immature cork layer and finally reach the wood.
STUDIES IN THE VARIETAL IMMUNITY OF POTATOES TO WART DISEASE (SYNCHYTRIUM ENDOBIOTICUM SCHILB., PERC.)
Authors: ROACH W. A.
Published: February 2008

Grafting experiments of a preliminary nature have been carried out to throw light on the functions of the various organs of the potato plant in rendering the tubers immune or susceptible to Wart Disease (Synchytrium endobioticum Schilb., Perc).

It is hoped that such knowledge may facilitate a biochemical study of the problem by indicating which part of the plant to investigate first, and to give some clue to the general nature of the chemical differences to be sought.

Composite plants were built up by grafting in the following ways:

3 plants of the type Immune grafted on Immune.

3 plants of the type Susceptible grafted on Immune

4 plants of the type Immune grafted on Immune Susceptible.

2 plants of the type Susceptible grafted on Immune

The results are in harmony with the conclusion that the character of the foliage has no influence on the immunity or the susceptibility of the tubers to Wart Disease.

It follows that no compound synthetised in the leaves is likely to be responsible for separating potatoes into “immunes” and “suscep‐tibles.”

The investigation is being continued, and it is hoped to determine whether any one part of the plant influences the immunity or susceptibility to the disease of any other part. The desirability of investigating a portion possessing such an influence is obvious. If the several parts of the plant have no such effect on each other, a search for differences in substances, such as the proteins, which are only translocated with difficulty, if at all, would be indicated.
STUDIES IN BACTERIOSIS. X
Authors: PAINE SYDNEY G. , LACEY MARGARET S.
Published: February 2008

Serum agglutination has been used in order to determine possible relationship with Bacillus lathyri of certain yellow organisms which occur in the tissues of plants infected by that organism.

One of these gave all the reactions of Pseudomonas Phaseoli.

Pseudomonas Phaseoli and Bacillus lathyri gave distinct cultural characters, and these were retained even after the two organisms had been “trained” by ten transfers through the same medium.

The two organisms seem to be susceptible to group agglutination, Bacillus lathyri being agglutinated with the serum of Pseudomonas Phaseoli.

Intermediate forms between these two organisms are found which agglutinate equally with the sera of both species.

The suggestion is made that one species may have arisen in the tissues of the plant as a mutant from the other.

Aplanobacter dissimulans, another organism often associated with Bacillus lathyri, appears to bear no sort of relationship with the latter.

Aplanobacter michiganense failed to produce an agglutinating serum on inoculation into a rabbit.
A STUDY OF THE FAUNA OF RIVERS POLLUTED BY LEAD MINING IN THE ABERYSTWYTH DISTRICT OF CARDIGANSHIRE
Authors: CARPENTER KATHLEEN E.
Published: February 2008

The relative poverty of the fauna and flora of certain streams in the Aberystwyth district can only be related to their pollution by lead mining and lead washing operations.

Such operations affect the rivers by the discharge into their waters of galena particles in all stages of division, and also by the formation of lead salts in diffusible form through chemical interaction with the natural water.

Only a single case is known of the clogging of fish‐gills by adhering particles of galena‐grit: there is no definite evidence that this is a usual cause of death.

Statistics locally collected shew, however, that such lead grit is present in practically all the streams of the neighbourhood, particularly in the Lower Clarach, where a rich fauna, including Fishes, subsists.

The correlation of fauna lists with tables of analyses of water samples shews that poverty of fauna, with absence of fishes in particular, always accompanies the presence of lead salts in diffusible form.

The cessation of the last of the lead mining and washing operations affecting the Rheidol and Ystwyth was followed by a marked and rapid increase in the flora and fauna of the rivers, which was accelerated by the spring drought of 1922. At this season, the amount of lead in diffusible form in these waters was, if any, too small to be estimated, while the proportion of lead grit remained high.

Observations made since May, 1922, shew that the original proportion of lead in diffusible form has not been restored, while the flora and fauna have continued to increase.

The general inference is that, while the presence of lead grit is no doubt in some cases directly harmful to Fishes, the general fauna of the rivers is undoubtedly impoverished by the presence of lead salts in diffusible form.
POTATO LEAF‐ROLL AND DEGENERATION IN YIELD
Authors: WHITEHEAD T.
Published: February 2008

Summary and Conclusions

The present communication summarises the first results of work now being carried out at the College farm, Aber, Bangor. It is to be regarded as a first progress report.

Quanjer's statement as to communicability of leaf‐roll by grafting tubers is confirmed.

The unlikelihood that ‘seed’ sterilisation will be useful as a measure of control is indicated by the failure to effect any control by steeping infected ‘seed’ in 1/1000 mercuric chloride for an hour and a quarter.

Cutting diseased tubers before planting did not affect the yield.

The loss in yield due to leaf‐roll was 55.8 per cent. in 1921, 45.6 per cent, in 1922 and 52.6 per cent, in 1923.

The effects of leaf‐roll do not appear to be cumulative under the conditions at Bangor.

The proportion of seed‐size and small tubers—as determined by relative weights and numbers—to total crop was not increased in the variety Arran Comrade as a result of infection with leaf‐roll.

The reduction in total number of tubers produced by a leaf‐roll crop was = 54.4 per cent, in 1922 and 61 per cent, in 1923.

The transference of leaf‐roll to healthy plants at Bangor in 1921 and 1922 has been studied. Evidence of soil transmission in 1921 is submitted. In 1922 both aerial and soil transmission is believed to have taken place.

Maximum infection in 1921 did not affect the yield in that year.

The relation of leaf‐roll to seed‐potato production is discussed.
THE INFLUENCE OF HYDROGEN‐ION CONCENTRATION ON THE GROWTH OF CERTAIN BACTERIAL PLANT PARASITES AND SAPROPHYTES
Authors: BERRIDGE EMILY M.
Published: February 2008

Summary and Discussion.

It is interesting to see in the foregoing series of experiments that most of the bacterial plant parasites, especially those of the Pseudomonas type, and the non‐parasitic species of the fluorescens type seem to possess three associated characteristics, namely high acid agglutination points and limits of growth, and a capacity to produce alkali rapidly in the presence of nitrogenous food materials. This latter capacity is shown in a less marked degree by other non‐sporing saprophytio organisms such as B. lactis aemgenes.

Many sporing species, on the other hand, appear to possess a different physiological constitution, since they produce acid in the earlier stages of growth in sugar‐free peptonized broth, and are characterized by comparatively low agglutination points and growth limits. Tests by Marchal and other observers (14) at a later period of their development have caused these sporing organisms to be regarded as the chief ammonia producers in the soil.

The experiments also show that the hydrogen‐ion only begins to act injuriously on the bacteria at concentrations about pH 5.0–4.4. Such hydrogen‐ion concentrations are seldom met with in plant tissues except in the case of acid fruits. The acidity of the cell sap has been determined by several investigators by the hydrogen electrode method; Clevenger(8) found that it varied from pH 4.33 for Buckwheat seedlings to pH 6.40 for Soy bean leaves. The values obtained by Hoagland(ii) for barley tops, by Phillips (17) for Indian Corn and Vicia faba, and by Wagner (21) by means of an indicator method for Sinapis alba, Brassica oleofera, Solanum tuberosum and Sempervivum Hausmanni all lie between pH 4.9 and pH 6.2. The cell sap used in these experiments was generally obtained by pressure of the tissues after grinding with sand; treatment of sections of fresh tissues with methyl red indicates that the acidity of the protoplasm itself is somewhat higher than that of the cell sap, whilst Atkins (1) found that the liquid centrif uged from the tracheae of Acer pseudoplatanus was neutral to litmus. Priestley (18) too remarks with respect to the sap collected from a bleeding vine stem, that, “tested with the usual series of indicators, the pH values of the sap in the vines was practically that of true neutrality.”
THE CROWN‐GALL DISEASE OF NURSERY STOCKS
Authors: WORMALD H. , GRUBB N. H.
Published: February 2008

An account is given of the galls (“crown‐gall”) found on layered apple stocks and on seedling apple trees raised at the East Mailing Fruit Research Station.

On the layered stocks the galls arise most frequently at the .base of the stocks, i.e. at the wound caused when removing the stock from the parent stool, but they may also occur on other parts of the stem below ground, and on the roots.

Observations extending over several years lead to the conclusion that, although galls have been found on every variety of layered apple stocks so far propagated at East Malling, some varieties are far more susceptible to crown‐gall than others.

Evidence has been obtained that the susceptibility of the stock is to some extent influenced by the variety of scion grafted on it.

No difference in vigour could be detected on the subsequent general growth of trees planted up with, or without, galls.
THE APPLE BUD WEEVIL, ANTHONOMUS CINCTUS, KOLL.
Authors: PETHERBRIDGE F. R. , COWLAND J. W.
Published: February 2008

Anthonomus cinctus is widely distributed on the Continent and occasionally, in certain districts, does serious damage to pear buds, and now and then is found injuring apples. In this country it is not yet recorded on pears, but was found killing apple buds at Wisbech, in 1921, and near Cambridge, in 1922. Adults have also been found in Kent.

The eggs are laid in apple buds (usually fruit buds) in the autumn, one egg only in each bud. The larva hatches at the end of February and eats out the succulent portion of the bud. It pupates in May and changes to the weevil stage in June. The weevils puncture the leaf stalks, buds and succulent portion of the shoots.

A description of the various stages is given.

A comparison is made between this species and those closely allied.

Near Cambridge Pimpla pomorum killed most of the larvae and pupae left on the trees after collecting.
FURTHER EXPERIMENTS IN THE CONTROL OF CERTAIN MAGGOTS ATTACKJNG THE ROOTS OF VEGETABLES
Authors: SMITH KENNETH M.
Published: February 2008

Experiments dealing with four species of root feeding maggots are described. The insects concerned are: Hylemyia antiqua, the onion fly; Psila rosae, the carrot fly; Chortophila brassicae, the cabbage root fly; and Ceuthorrhynchus pleurostigma, the turnip gall weevil.

Control experiments on the first two have been carried on since 1920. A list of all the chemicals used in these trials is given.

As a result of the 1924 experiments the following are recommended for use against onion fly: (a) nicotine sulphate dust, in a 5 per cent. mixture with precipitated chalk; (b) chlor‐cresylic acid, in a 1 per cent, mixture with precipitated chalk.

After three seasons' trials creosote is not considered an efficient remedy for onion fly.

For carrot fly: (a) nicotine sulphate dust in a 6 per cent. mixture; and (b) creosote, in a 1 per cent. mixture, both in chalk, gave promising results in the 1924 trials.

Of chemicals wed in field trials against the cabbage root maggot the most successful were: (a) chlor‐cresylic acid, (b) green tar oil, (c) creosote. Anthracene oil and nicotine sulphate also gave fair results.

A number of pot experiments, designed to test the efficacy of corrosive sublimate as a control for cabbage root maggot, were carried out. Results do not appear to justify the use of this substance as a remedy, but further trial is necessary.

400 cabbages, 200 galled by the larvae of the turnip gall weevil and 200 healthy, were grown under test conditions in order to ascertain the effect of these galls upon the health of the plant. The results of this experiment indicate that firstly the galls are attractive to slugs and secondly that the critical time in the life of a galled cabbage is the seedling stage, but that given good cultural conditions at the time of setting out, the cabbage will flourish normally.
A DISEASE OF WILD WHITE CLOVER CAUSED BY THE EELWORM, TYLENCHUS DIPSACI (KÜHN) BASTIAN
Authors: WARE W. M.
Published: February 2008

A disease of white clover, due to the eelworm, Tylenchus dipsaci, has been found to cause serious harm. This and other diseases are thought to be partly responsible for the lack of permanence sometimes ascribed to strains of white clover. In tests of the susceptibility shown by various clovers to the attacks of the eelworm from wild white clover, remarkable resistance was shown by red clovers and the maximum susceptibility by cultivated white clovers. The suggestion is made that in future tests of the relative susceptibility of various plants to attack by this parasite, the former hosts of the eelworm should be taken into account.

A grant in aid of this and other work in connection with wild white clover was made by the Ministry of Agriculture.

Thanks are due also to Mr Harald Faber, Agricultural Commissioner to the Danish Government, to Messrs Donaldson & Co., and to Messrs Gartons Ltd. for kindly supplying many of the seeds used.
REVERSION DISEASE OF BLACK CURRANTS: MEANS OF INFECTION
Authors: LEES A. H.
Published: February 2008

This paper is a continuation of previous work on Reversion Disease of Black Currants, and deals more especially with the possible means of infection.

Evidence is put forward showing that the disease can be propagated by contact of diseased material with healthy, either by grafting or by pruning with a contaminated pruning tool.

The disease, after it has attained entry, is propagated slowly downwards.

The rate at which it travels appears to depend on the intensity of the original infection, and there is some evidence to show that the intensity of the resulting disease is also similarly dependent.

Propagation can be independent of Black currant mite, Eriophyes ribis.

There is no evidence of occurrence of the disease solely on the ground of proximity of healthy and infected plants.

There is some evidence in support of the possibility of a pest carrier.
STUDIES ON THE SEX‐RATIO AND RELATED PHENOMENA: 6. THE EFFECT OF POLYGYNY.
Authors: PARKES A. S.
Published: February 2008

(1) The evidence relating to the effect of polygyny on the sex‐ratio in man is conflicting, but the result, if any, appears to be a rise in the proportion of males.

(2) In horses Düsing has shown that the proportion of males rises with increased stud work.

(3) The experimental work on mice described in this paper shows that in this mammal a rise in the pescentage of males follows polygynous mating, and therefore supports Düsing's results.
STUDIES ON CONTACT INSECTICIDES: PART III. A QUANTITATIVE EXAMINATION OF THE INSECTICIDAL ACTION OF TKE CHLOR‐, NITRO‐ AND HYDROXYL DERIVATIVES OF BENZENE AND NAPHTHALENE
Authors: TATTERSFIELD F. , GIMINGHAM C. T. , MORRIS H. M.
Published: February 2008

1. The toxicities of a number of chlor‐, nitro‐ and hydroxyl‐derivatives of aromatic hydrocarbons to Aphis rumicis L. (adults) and to Selenia tetralunaria Hufn. (eggs) have been determined.

2. The order of toxicity to the aphides of the hydrocarbons and their chlor‐ and nitro‐derivatives is benzene < toluene < sylene < monochlor‐benzene < p‐dichlor‐benzene < o‐dichlor‐benzene < trichlor‐benzene < nitro‐benzene < m‐dinitro‐henzene. The mono‐chlor‐nitro‐benzenes have about the same toxicity as nitro‐benzene; l‐chlor‐2: 4–dinitro‐benzene is slightly less toxic than m‐dinitro‐benzene.

3. Phenol and the three isomeric cresols are toxic to aphides only at high concentrations. The mono‐nitro‐phenols and cresols are all mare toxic than the parent substances, the order of toxicity of the phenol being o‐nitro‐phenol < m‐nitro‐phenol and p‐nitro‐phenol < 2: 4–dinitro‐phenol > trinitro‐phenol; and the same order applies to the cresols and their corresponding derivatives.

4. α‐chlor‐naphthalene proved to be the most toxic of the naphthalene‐derivatives tested.

5. With few exceptions, the relative toxicities of the various compounds to the insect eggs are approximately in the same order as to the aphides. The nitro‐derivatives of phenol and the cresols were specially studied and it was shown that, as in the case of aphides, the dinitro‐compounds are more toxic to eggs than either the mono‐ or the tri‐nitrocompounds.

6. 3:5–dinitro‐o‐cresol is shown to have a toxicity both to adults of Aphis rumicis and to eggs of Selenia tetralunaria which is of the same order as that of nicotine.

7. Some of the compounds tested may prove to be of value as winter spray fluids for trees in a dormant condition although injurious to foliage, and experiments on a practical scale are in hand.

8. A consideration of the results as a whole leads to the conclusion that no simple generalisation as to the correlation of toxicity with any one chemical or physical property is possible in the present stage of our knowledge. It is probable that the nature of the toxic activity depends on chemical constitution whereas intensity of activity is determined by one or more physical properties.
STUDIES ON OSCINELLA FRIT, LINN.: A PRELIMINARY INVESTIGATION OF THE EXTENT OF THE RECOVERY POWER OF OATS WHEN SUBJECT TO INJURY.
Authors: CUNLIFFE NORMAN
Published: February 2008

In the summer of 1924 an investigation of the extent of the recovery power of oats after injury approximately similar to that caused by Oscinella frit Linn. was conducted under experimental conditions. The larval attack in spring was simulated by killing the growing points of the stems [(1) main stem only and (2) main stem plus first two tillers] and growth records were obtained after a limited period of time. The varieties of spring oat, Scotch Potato and Sir Douglas Haig were used, being prolific and poor tillerers respectively. The oats were sown on April 13th, were above ground on April 26th, treated (1) May 27th and (2) June 6th, the crop being harvested during the third week in August.

1. Undamaged Haig plants produced a less number of panicles than undamaged Potato plants by 21 per cent. With Potato, loss of main stem alone and loss of the first three shoots caused a reduction of about 40 per cent. in panicle production, With Haig, recovery after subjection to the first type of damage was almost complete, and as good as that exhibited by Potato after the second type of damage.

2. With regard to height of fruiting stem, a reduction of about 20 per cent. was observed after the more severe treatment with both varieties.

3. Spikeleh production varied greatly with variety, Potato carrying twice as many spikelets per fruiting stem as Haig. Tillers produced after the loss of the main stem carried no more spikelets than the normal tillers, i.e. about 30 per cent. less than the mean of the stems of the control plants. Tillers formed after the loss of three stems exhibited a reduction of 50 per cent. in spikelet production.

4. Yield of grain was not recovered by Potato after loss of the main stem (reduction 60 per cent. by weight), whereas Haig to a great extent recovered its yield. Loss of the first three stems caused a reduction of 80 per cent. in both cases, the additional reductions not however being significant in these experiments. Owing to the production of a greater number of seed, however, Potato yielded almost as well after losing its main stem as Haig did when undamaged. The variations in yield of straw were of the same order as those observed for yield of grain.

5. Recovery power after injury would appear to be much more marked with Haig than with Potato, and cannot necessarily be forecasted from a knowledge of tillering capacity. Under field conditions, where capability of covering the ground after losses may be comparatively small, as in the case of a weak tillering variety (although poor initial tillering capacity may be compensated for by an increased population), an oat like Potato might give a better yield of produce than one like Haig, even although Haig may exhibit greater recuperative powers than Potato. This problem is of course intimately related to the general problem of yield, which itself still awaits solution.
STUDIES IN CACAO
Authors: BGRLBND S. C.
Published: February 2008

Previous investigations on the pollination of cacao are reviewed. It is pointed out that the consensus of opinion is in favour of the pollinating agent being small insects, either thrips, aphides or ants.

Direct proof of natural crossing was obtained by examination of flowers on a male sterile tree, in which 9 per cent. of the flowers were found to be pollinated.

Daily examination of flowers artificially pollinated, flowers attended by ants and aphides, and flowers with no attendant insects, indicated that the majority of cacao flowers are never pollinated under Trinidad conditions. Adequate pollination took place in 35 per cent. of flowers attended by ants and aphides, and is only 6 per cent of the controls. It is concluded that ants and aphides are the chief pollinating agents in the field under examination.

Elimination of crawling insects demonstrated the presence of another pollinating agent, probably a night flying insect which pollinated about 1 per cent. of flowers.
THE TRANSMISSIOK OF STREAK DISEASE OF MAIZE BY THE LEAFHOPPER BALCLUTHA MBILA NALIDE
Authors: STORES H. H.
Published: February 2008

In the absence of transmission of streak disease by the seed, the wide occurrence of this disease in maize in South Africa is accounted for by infection of the plants at some period after their appearance above ground. It has been shown that plants may be protected from infection by growing them in a greenhouse or under wire‐gauze of not less than 32 meshes to the inch.

A number of insects have been tested as possible vectors of streak disease, and positive results have been obtained with a jassid, Balclutha mbila Naude. In four cases out of five, to each of which were introduced three or four adults of this species, collected on streak‐diseased maize, the disease developed in every plant. The plants hi three similar cages, to which no jassids were introduced, remained healthy.

In experiments in which single individuals of Balclutha mbila, collected upon streak‐diseased maize, were allowed to feed upon single leaves of the experimental plants, the disease resulted in 46 out of 48 plants. One jassid lived for five months and carried the disease to eight separate plants. No loss of the power of infection occurred in any jassid tested, in spite of periods of starvation in some cases or of feeding on apparently immune plants in others. Certain individuals, collected upon streaked maize were incapable of causing any infection under similar conditions.

Jassids reared upon healthy maize were incapable of infecting plants with streak disease. But after feeding upon a diseased leaf for a week, 26 per cent. of the males and 86 per cent of the females, out of a total of 62 individuals, became infective.

Negative results were obtained in trials of Aphis maidis Fitch, Peregrinus maidis Ashmead and a number of undetermined jassids and fulgorids.

Field observations showed that Balclutha mbila was to be found, although infrequently, whenever a field of maize, recently infected with streak disease, was thoroughly searched. It is held therefore to be the agent of spread of the disease in the field.
STUDIES IN BACTERIOSIS. XIII: A SOFT ROT OF POTATO TUBERS DUE TOBACILLUS CAROTOVORUSAND A COMPARISON OF THE CULTURAL, PATHOLOGICAL AND SEROLOGICAL BEHAVIOUR OF VARIOUS ORGANISMS CAUSING SOFT ROTS
Authors: LACEY MARGARET S.
Published: February 2008

An internal soft rot of potato tubers caused byB. carotovorusis described. Various strains ofB. phytophthorus, B. solanisaprusandB. carotovorusare compared with respect to their cultural, pathological and serological behaviour, and the differences seem sufficient to warrant their continued separation into distinct species.
THE VIABILITY OF THE WINTER SPORANGIUM OF SYNCHYTRIUM ENDOBIOTICUM (SCHILB.) PERC., THE ORGANISM CAUSING WART DISEASE IN POTATO
Authors: GLYNNE MARY D.
Published: February 2008

A staining method for testing the viability of the winter sporangia of Synchytrium endobioticum is described. The sporangial contents are pressed out into acid fuchsin or after treatment by a strongly alkaline reagent into methylene blue. The staining reactions have been correlated with the results of infection experiments in pots. Sporangia which, like the controls stain faintly, produce a high percentage infection and are therefore alive. Those which stain deeply and rapidly produce no infection and are presumably dead. There is an intermediate group in which some sporangia stain deeply and some are intermediate in reaction. This group tends to give less infection than the controls.

A method whereby sporangia which have been treated in soil may be extracted without affecting their viability is described. The method depends on the difference in specific gravity of sporangia which has been determined as about 1.17 and of soil which is in the region of 2.5. The sporangia are extracted by means of chloroform (sp. gr. 1.5 approx.), which does not affect their viability.

A study of the relation of temperature, time and viability shows that treatment for 5 minutes at 90°C., 15 minutes at 80°C., 1 hour at 70°C. and 8 hours at 60°C. have a similar effect in killing all the sporangia.
THE MEMBERS OF THE GENUS AGROSTIS IMPORTANT IN THE SEED TRADE, WITH SPECIAL REFERENCE TO THE NOMENCLATURE
Authors: NELSON ALEXANDER
Published: February 2008

The paper deals with the members of the genus Agrostis occurring in the international seed trade; current names are enumerated and, as far as possible, related to each other.

The following relationships are established:
THE EFFECT OF SOME SOIL CONDITIONS ON NODULE FORMATION ON CROTALARIA JUNCEA (L.)1
Authors: GANGULEE N.
Published: February 2008

From pot culture experiments in the greenhouse it has been shown that the formation of nodules on the roots of Crotalaria juncea is affected significantly by variations in the texture, moisture content and reaction of the soil, all other conditions being kept uniform. Nodule formation was increased by higher moisture content, by increased coarseness and by reduced hydrogen ion concentration.
NOTE ON THE OCCURRENCE OF DISEASED SHOOTS ARISING FROM POTATO‐TUBERS INFECTED BY PHYTOPHTHORA INFESTANS
Authors: SALMON Professor E. S. , WAKE W. M.
Published: February 2008

A résumé is given of the work of those investigators who have recorded the occurrence of diseased shoots arising from potato tubers infected by P. infestans.

An experiment is recorded in which of 25 naturally infected tubers planted early in April in pots in the greenhouse, 2 produced by May 16th short diseased shoots, which developed conidiophores and spores. These shoots, doubtless infected ab initio by mycelium growing from the tuber, were closely similar to those which have been described by de Bary and other investigators.

A probable case of secondary infection was observed on a leaf on one of the healthy shoots of a plant which produced a diseased shoot.
STUDIES ON THE LUCERNE NODULE ORGANISM (B. RADICICOLA) UNDER LABORATORY CONDITIONS
Authors: GANGULEE N.
Published: February 2008

It is observed that on whatever media the organism is growing, whether in liquid or agar or in soil, the various stages of the life‐cycle are found to occur simultaneously, but in varying proportions. The soil conditions, such as aeration, temperature and the presence of certain salts, are among the factors that determine which of the stages shall be in predominance. The relative efficiency of liquid and solid media in bringing about the predominance of a particular form was also studied.

In the main, the existence of the five stages in the life‐cycle of the organism observed by Bewley and Hutchinson is confirmed; but evidence is obtained to show that under very favourable conditions the motile cocci (“swarmer”) can emerge directly from the banded rod stage, developing flagella even, before their emergence, and therefore missing out the non‐motile (“pre‐swarmer”) stage.

The appearance of coccoid bodies is observed to have been accelerated in the presence of saccharose, mannite and phosphates (in agar media) and also in soil extract alone. Short rods are elongated cocci and they tend to persist in media containing the ingredients mentioned above.

The formation of “pre‐swarmers” has been ascribed to unfavourable conditions, such as deficiency of food, or excess of calcium carbonate in the media, or inadequate aeration. A closer study of the morphological variations, however, shows that the banded rods are associated with such conditions.

Comparing the morphological variation with the number of organisms in a given time, it appears that changes in morphology are accompanied by marked alterations in the bacterial activity. The percentage increase of cocci and short rods in soil is found to be correlated with an increased total number of organisms.

The writer wishes to acknowledge his indebtedness to Mr P. H. H. Gray for giving him much valuable advice and criticism in the course of the investigation.
THE GROWTH OF YOUNG MICE ACCORDING TO SIZE OF LITTER
Authors: PARKES A. S.
Published: February 2008

Four hundred and seven young albino mice produced in 66 litters had an average weight of 1.41 gm. at birth and of 7.14 gnu at weaning time (3 weeks old).

These average values vary very considerably, but uniformly according to size of litter. Individuals from litters of 2 and litters of 10 averaged respectively 1.0 gm. and 1.6 gm. at birth, and 4.45 gm. and 11.75 gm. at weaning time. Individuals from the intermediate sizes of litter grade fairly evenly in between these extremes. The whole growth during suckling is in fact inversely proportional to the size of litter.

Growth during suckling is characterised by the active phases in the first and third weeks respectively and a comparatively stagnant period in between.

These results can all be explained on a basis of differential nutrition.
A QUANTITATIVE EXAMINATION OF THE TOXI‐CITY OF 3:5‐DINITRO‐O‐CRESOL AND OTHER COMPOUNDS TO INSECT EGGS, UNDER LABORATORY AND FIELD CONDITIONS
Authors: GIMINGHAM C. T. , MASSEE A. M. , TATTERSFIELD F.
Published: February 2008

The toxicity of 3: 5‐dinitro‐o‐cresol and its sodium salt to eggs of the moth Selenia tetralunaria Hüfn, has been determined quantitatively under controlled conditions in the laboratory. The figures obtained confirm earlier results and show (a) that these compounds have a very high toxicity to insect eggs, and (b) that the sodium salt of dinitro‐o‐cresol is only slightly less toxic than dinitro‐o‐cresol in the uncombined state. The relationship between concentration and toxicity is expressed by means of diagrams.

Preliminary laboratory experiments indicate that dinitro‐o‐cresol is also highly toxic to insect eggs of a more resistant type than those of S. tetralunaria.

Spray fluids containing dinitro‐o‐cresol or the sodium salt showed a high efficiency against eggs of the Hop‐Damson Aphis (Phorodon humuli Schr.) on plum trees on a larger scale under field conditions. The trees sprayed with these compounds remained almost free from aphides during the following spring when the control trees were badly infested.

A quantitative method for judging the results of the field experiments was worked out. This involved recording details of large numbers of eggs on selected shoots on sprayed and control trees before and after spraying, a numerical measure of the effect of the various treatments being thus obtained. The method gave consistent and reliable results.

The spray fluids containing dinitro‐o‐cresol and its sodium salt had a marked general cleansing effect on the trees. No injury to the trees was observed.