bluuebunny/crossref_metadata_2025 huggingface dataset:
THE INTIONS OF ENVIRONMENTAL CONDITIONS ON THE DEVELOPMENT OF THE ANGULAR LEAF‐SPOT DISEASE OF COTTON: III. The Influence Of Air Temperature On Infection
Authors: STOUGHTON R. H.
Published: February 2008

Summary.

Experiments carried out in the Rothamsted control chambers on the influence of air temperature on the angular leaf‐spot disease of cotton plants, resulting from spray inoculation of young plants, show that high air temperatures favour the development of the disease. Maximum infection occurs at an air temperature of 35–36° C. with decreasing incidence at progressively lower temperatures. At a constant air temperature of 39–40° C. cotton plants make no growth and eventually die.

Infection takes place more readily when the inoculation is carried out during the non‐illuminated period.

The relation of these results to the experiments on the influence of soil temperature is discussed.
The Absorption Of Water By Seeds Of Lolium Perenne (L.) AND Certain Other Gramineae
Authors: BROWN R.
Published: February 2008

Summary.

1. The methods used in these investigations into the problems of absorption of water by seeds are described. A modification in the method of direct weighing is suggested.

2. The rôle of the pale in absorption is discussed. The pale exercises a retarding effect on water absorption, so long as it is attached to the caryopsis. But the attachment is broken as the absorption of water with consequent swelling extends from base to apex.

3. The cuticular membranes of the seed retard the absorption of water, but the permeability is increased by the stretching of the cuticle, consequent upon swelling.

4. The earliest absorption takes place through the micropyle. This water can diffuse upwards to a certain extent. At the higher level it causes the endosperm to swell, which in its turn induces greater permeability of the cuticular membranes. The water absorbed at this higher level diffuses upwards to a slight extent, and causes greater permeability at a still higher level. Thus, there is a progressive extension upwards of the area of absorption induced by the slight upward diffusion of water.

The writer wishes to acknowledge his indebtedness to Prof. W. Stiles for help in the preparation of the manuscript of this paper; to Mr F. R. Horne for help in the course of the work; and to Mr R. L. Stevenson for making the diagrams which accompany this paper.
The Problem Of “Potato Sickness”: A Report Upon Certain Experiments
Authors: BUCKHURST A. S. , FRYER J. C. F.
Published: February 2008

Summary.

1. A study of the causes of “potato sickness” has been made during the past two years, both in the field and by means of pot experiments.

2. The sickness does not occur in the absence of the nematode H. schachtii, but potato plants may grow normaliy even when heavily attacked by this eelworm. No correlation was found between the cyst content of the soil and the intensity of the sickness.

3. There is no reason to suspect that the fungus C. Solani plays any primary part in causing the sickness, and no other parasitic organism (apart from the eelworm) likely to be responsible for the trouble was discovered.

4. The evidence suggests that the sickness is due to an attack by the eelworm in conjunction with a soil factor that inhibits a vigorous early growth of roots; it is possible that this second factor is a nutritional defect which is not made good by the ordinary manurial measures adopted in potato‐growing districts.
FUSARIUM SPECIES ON BRITISH CEREALS
Authors: BENNETT P. T.
Published: February 2008

F. Scirpi Lamb, et Fautr., previously described in its pseudopionnotal form, occurs in a mycelial form also; the cultural characters and method for conversion of the forms are given.

This variety is designated pallens to distinguish it from a new variety designated nigrans. also occurring on cereals. The relationship of the two varieties is discussed.

Both varieties are associated with Fusarium disease in cereals, but are of little economic importance except when the variety pallens prevails on the ears of wheat and barley; infected grains used for seed, if still viable, give less vigorous plants and reduced yield of corn.
Studies on plant virus diseases1
Authors: SMITH KENNETH M.
Published: February 2008

Further studies upon a ringspot virus are described and the following points in the work are emphasised:

The insect Thrips tabaci Lind. is found to be an efficient vector of the virus.

The technique and methods of Thrips management are described.

Evidence is presented which indicates that the ringspot virus previously described from Solatium capsicastrum is identical with the tomato virus known in Australia as spotted wilt.

The host range of the virus has been studied. All species of Solanaceae tested, i.e. twenty in number, were found to be susceptible to the disease, and in addition the virus has been transmitted to Lupins, Dahlias, Asters, Zinnias and Plantains.

The spotted wilt virus was found not to pass an ix Pasteur‐Chamberland candle, and its viability was lost after 4 hours' ageing in vitro. An accurate method of testing the longevity in vitro of the virus is obtained by making use of the special reaction of the Petunia plant to the disease.

A comparison is given of the virus of tomato spotted wilt with a tomato virus of the stripe or mosaic type associated with it.
CULTURAL STUDIES ON THE ASPERGILLI, WITH SPECIAL REFERENCE TO LIPASE PRODUCTION OF STRAINS ISOLATED FROM STORED COPRA AND CACAO
Authors: EYRE J. C.
Published: February 2008

‐Thirteen strains of Aspergillus, including four of A. niger and two of A. flavus, one strain each of Mucor racemosus and Syncephalastrum cinereum and a blue‐green Penicillium are dealt with in this paper. They were isolated from stored products, mainly copra and cacao. Determinations were made of the lipolytic activity of the dried mould, the weight of dried mould produced and the lipolytic activity, titratable acidity, and pH. of the liquid Czapek medium in which the moulds were grown. The influence of an increase in temperature was also investigated.

Figures are given for the lipolytic activity for 2 weeks' growth and in the case of some species also for 4 and for 8 weeks' growth. All the strains were found to be lipolytically active both as regards the medium and as regards the dried mould. On a basis of 2 weeks' growth the strains of Aspergillus were divided into two distinct classes in relation to the amount of lipase found in the medium. In the case of the activity of the dried mould two classes were again found. With two exceptions the same moulds were found to be in the same class in both cases.

It was found that while the lipolytic activity of the dried mould and of the medium were materially the same at 2 weeks as at 4 weeks, determinations made at 8 weeks indicated an increase in the activity of the medium and a decrease in the activity of the dried mould coincident with a decrease in the weight of growth. It is therefore suggested that the increase in the activity of the medium is due to autolysis and probably also to an increased excretion of enzyme.

As it was found that the amount of lipase in a medium containing coconut oil as the source of carbon was much greater than in a sucrose medium it is concluded that the coconut oil stimulated the production of the enzyme.

In the case of the Aspergilli there was a definite correlation between the colour of the mould, the colour of the medium and the titrat‐able acidity of the medium. The lighter coloured forms produced least acid and most colour in the medium, while the dark forms produced most acid and least colour. On autolysis the depth of colour of the medium increased and the titratable acidity decreased.

Marked differences in the titratable acidity of the medium were found between the four strains.of A. niger. An mcrease of temperature had the effect of bringing about still more marked differences and in addition, differences in lipolytic activity. No qualitative differences were found.

A. niger (copra), A. flavus (light), A. tamarii and A. sydowi were grown on a coconut oil emulsion. The rates at which the different species clarified the emulsion were noted. A. niger and A. flavus clarified the emulsion in the shortest time. The addition of sucrose had the effect of considerably retarding the assimilation of the oil in the emulsion.
ON A SUGGESTED METHOD FOR DETERMINING THE NUMBER OF LARVAL INSTARS IN SITODREPA PANIGEA L.
Authors: METCALFE MARGOT E.
Published: February 2008

SUMMRY AND CONCLUSIONS

A number (887) of larvae of Sitodrepa panicea L. were examined with a view to testing the application of Dyar's law and the possibility estimating the number of larval instars by measuring the head capsule a random population.

The measurements were found to fall into two groups, one slightly larger than the other, whose growth ratios approximated to two geometrical series, one with a common ratio of 1–12, the other with a common ratio of 1.11.

It is suggested that these two groups represent the sexes.

On this hypothesis it would appear that the males undergo a minimum of four larval ecdyses, and the females a minimum of five. Miles (loc. cit,) postulates a similar phenomenon for several species of Tenthredinidae. Furthermore, the sex ratio is not unity.

The method of investigating the growth ratio of the larva by the measurement of a large population, is not entirely satisfactory. Owing to diversity of causes such as the periodicity of egg‐laying, insufficient numbers of the young larvae were obtained, and no satisfactory conclusions with regard to the number of these early instars can be reached.

The analysis of the data is further complicated by the variation in size and presumed overlapping of the instars in both sexes.

Until much larger and more representative populations, or many more samples of small populations can be examined, such a method of determining the number of larval instars in a given insect can be but of debatable value.
THE EFFECT OF SEED DISINFECTION UPON THE OAT CROP IN NORTHERN IRELAND
Authors: MUSKETT ARTHUR E. , CAIRNS HUGH
Published: February 2008

This paper deals with a series of experiments carried out in Northern Ireland over a period of three years in order to determine the value of various seed treatments for controlling smuts and for use as general seed disinfectants in connection with the cultivation of the oat crop.

In so far as the control of oat smuts is concerned and at the concentrations used in these experiments, copper sulphate and copper carbonate proved to be of some value but caused definite injury to the crop, while sulphur and gypsum proved to have no fungicidal value. Formaldehyde gave complete control in nearly every case, the sprinkle method being considered more satisfactory than steeping, as it is more easily carried out and as the results obtained indicate that in some cases steeping may cause crop injury. The organic mercurial–“Ceresan”– gave almost as good results as formaldehyde.

As general seed disinfectants the organic mercurials–“Ceresan” and “Abavit B”–proved to be more satisfactory than formaldehyde, the average increase in grain yield from these plots being approximately 30 per cent, above the yield from the formaldehyde plots which in turn showed a yield increase of 16 per cent above the controls.

It is suggested that the greater efficiency of organic mercurials is due to the fact that the fungicide is retained by the grain at the time of sowing and remains operative during the early stages of crop development without causing injury to the plants.

The fact that oat grain has been treated with “Ceresan” and “Abavit B” at varying intervals before sowing with complete success indicates that this method of treatment possesses a distinct advantage over the formaldehyde method where, in order to preclude possibly injury during germination, it is necessary to carry out the treatment immediately prior to sowing. No causes of poisoning as a result of the use of organic mercurials have occurred so far and it is possible that by taking reasonable precaution the. use of these compounds for seed dressing may be safely advocated.
THE EFFECT OF COLPIDIUM ON AMMONIA PRODUCTION BY SOIL BACTERIA
Authors: MEIKLEJOHN JANE
Published: February 2008

Two series of experiments were performed with a mixed culture of two species of soil bacteria with and without Colpidia, one series on a solution of peptone in soil extract, the other on a synthetic medium containing alanine.

An appreciable reduction in bacterial numbers was found on both media to occur in the Colpidium cultures as compared with the controls.

On the peptone medium the Colpidium cultures produced slightly more ammonia than the controls, in spite of their lower numbers of bacteria.

On the alanine medium the Colpidium cultures produced nearly the same amount of carbon dioxide and of ammonia as the controls.

In both series of experiments an inverse linear relation was found to exist between bacterial numbers and efficiency of ammonia production, and the same was found for carbon dioxide production in the second series.

The regression coefficients of efficiency on average bacterial numbers are significantly different in the Colpidium and control cultures fo the second series.

It follows that the stimulating effect of the presence of Colpidia is not due solely to the reduction of bacterial numbers to an optimum value, and it is suggested that in the cultures in which Colpidia are present, the bacteria are kept in a state of youth for a longer period.
THE DEVELOPMENT OF ASSIMILATORY TISSUE IN SOLANACEOUS HOSTS INFECTED WITH AUCUBA MOSAIC OF TOMATO
Authors: SHEFFIELD F. M. L.
Published: February 2008

The development of the chloroplasts in Solatium nodiflorum, S. lycopersicum and Nicotiana tabacum is described and comparisons are made with plants infected with aucuba mosaic.

In the normal plants after cell division ceases in the meristematic tissue certain minute bodies, which are present in the cytoplasm of all young cells, commence to enlarge. A vacuole is formed in each and this gets bigger as the proplastid increases in size. A starch grain is formed in the vacuole. The outer stroma becomes pigmented and pores are formed in it. Increase in size continues, the mature plastid being about 5/i in diameter. A second or third starch grain may be formed in the vacuole. Chloroplasts sometimes divide.

In plants infected with aucuba mosaic certain of the leaf tissues are devoid of plastids and the cells may be undifferentiated. The absence of chlorophyll is brought about by the inhibition by the virus of the development of the plastid primordia. Usually the primordia are destroyed. If plastid development is not prevented in a very early stage, perfectly normal plastids are formed. Mature plastids are never affected by the virus but occasionally intermediate stages may be.

Intracellular inclusion bodies are not found in meristematic tissue, but incipient bodies appear when the cells are increasing in size and after plastid development is well advanced. For this reason inclusion bodies are formed indiscriminately in green and chlorotic areas, the virus presumably having reached the green tissues too late to inhibit plastid development.

An attempt was made to determine whether the prevalence of intracellular inclusion bodies in tegumentary tissues and their rarity in assimilatory tissues is due to differences in the pH of the tissues but the results obtained were rather indefinite.

This work was carried out under the auspices of the Empire Marketing Board.
THE BIOLOGICAL DECOMPOSITION OF PLANT MATERIALS PART VIII. THE AVAILABILITY OF THE NITROGEN OF FUNGAL TISSUES
Authors: NORMAN A. GEOFFREY
Published: February 2008

Various aspects of the availability of the nitrogen, of fungal tissue to micro‐organisms have been investigated, with particular reference to the influence of the C/N ratio of the material.

Fungal tissue was found to be as suitable a source of nitrogen as ammonium salts and nitrates for the decomposition of straw both by a mixed soil flora and by pure cultures of certain fungi.

The liberation of ammonia in sand culture from fungal tissue by pure cultures of reputedly active ammonifiers was measured.

The nitrification in soils of a number of samples of fungus tissue was compared with that of artificial mixtures of equal C/N ratio built up from glucose, cellulose and straw, each with added inorganic nitrogen.

A very clear correlation was found between the C/N ratio of the fungal material and the nitrogen nitrified. In one series in hill‐side soil nitrification increased from 42 to 80 per cent, in 6 months as the ratio decreased from 15.8 to 5.5; in another, from 20 to 75 per cent, as the ratio decreased from 17 to 7.

No evidence was found for the existence of a very resistant and unnitrifiable residue from fungal tissue as claimed by some workers, and incomplete nitrification is probably due to the attainment of biological equilibrium or of a state in which change is very slow.
DASYNEUMA LEGUMINICOLA (LINT.) THE CLOVER SEED MIDGE
Authors: METCALFE MARGOT E.
Published: February 2008

The life history of the clover‐seed midge has been studied, and methods of control are discussed. The midge destroying clover seed in England is Dasyneura leguminicola Lint., the species common in the United States. It is typically two brooded and the second brood overwinters in the larval state. There are four larval instars.

An attempt was made to establish the immunity of a variety of red clover, but all the varieties used were susceptible to attack. White clover was not attacked. It is suggested that unless an immune variety can be produced, clovers grown for seed production should be chosen with a view to their being in the green‐head either before or after the time of maximum emergence of the midges (e.g. the week from May 28th to June 4th in Harpenden). Furthermore, if cutting of the first crop is used as a means for destruction of the second brood of midges, this should take place within 10 days of the crest of emergence of the midges, the farmer deriving what information he requires from the advisory entomologist of his particular district.
PINK ROT OF THE POTATO
Authors: CAIRNS H. , MUSKETT A. E.
Published: February 2008

1. A survey of the occurrence and importance of pink rot of the potato is given. The disease is widespread in Britain, but is only occasionally of serious economic importance.

2. The nature of pink rot is explained and it is shown how the disease may be caused by more than one pathogenic fungus. Phytophthora erythroseptica Pethybr. is the normal pathogene, but two other species of Phytophthora have been recorded as causing the disease in the field, viz. P. drechsleri Tucker in the U.S.A. and P. megasperma Drechsler in Northern Ireland.

3. The disease may be systemic in the potato plant, causing “misses” and “pink rot wilt” in the crop; normally, however, it is of importance only as a disease of the tuber.

4. Under conditions of high humidity and poor aeration the disease may cause heavy loss in an affected crop during storage.

5. Under normal conditions in the field the tuber becomes infected via the mother stolon; if conditions in the field or store are sufficiently moist, however, the tuber becomes infected directly, generally through the “eyes.”

6. Varietal susceptibility of the potato has been considered on the three bases: (a) artificial infection of the tuber with P. erythroseptica, (b) natural infection of the tuber when stored in contaminated soil, (c) susceptibility in the field when planted in contaminated soil. Altogether fifty‐one varieties (including nine mentioned as susceptible by Pethybridge and which were not tested) have been considered, all of which proved to be more or less suceptible. No variety was found to be particularly resistant.

7. Large numbers of oospores are produced by P. erythroseptica in the haulms and stolons and also to some extent in the roots of the dead potato plant. These oospores become disseminated and greatly increase the prevalence of the fungus in the soil.

8. It has been shown that, in the absence of the host plant, the fungus may persist indefinitely in the soil. This persistence is apparently principally due to the resting spores, but the fact that the fungus may exist to some extent as a saprophyte in the soil cannot be ruled out.

9. The disease may be satisfactorily controlled in practice by paying attention to the general principles of crop hygiene. Satisfactory crops can be grown in contaminated soil, provided that strongly sprouted tubers are planted and that soil drainage is sufficiently good to prevent the land from becoming unduly wet in times of heavy rainfall. Early harvesting of the crop tends to secure a minimum percentage of affected tubers at the time of digging. Prevention of the spread of the disease during storage may be obtained by ensuring dry and well aerated conditions in the store.

The writers wish to express their very sincere thanks to Mr A. Murray, Culnafay, Toomebridge, County Antrim, who has given every facility for the carrying out of field experiments on his farm, and to the Potato Inspectors in Northern Ireland who assisted in recording occurrences of the disease.
AN EXPERIMENT ON THE INCIDENCE AND SPREAD OF ANGULAR LEAF‐SPOT DISEASE OF COTTON IN UGANDA
Authors: HANSFORD C. G. , HOSKING H. R. , STOUGHTON R. H. , YATES F.
Published: February 2008

Experiments on the incidence and spread of the angular leaf‐spot disease of cotton, carried out at two centres in Uganda, are described.

Treatment of the seed by sterilisation with sulphuric acid and mercuric chloride resulted in a reduction in the amount of the disease throughout the season.

Treatment of the seed with a bactericidal dust had a significant effect on total germination, the plots sown with this seed having a greater number of plants at the end of the season, independently of those killed by the disease.

Primary infection was almost entirely limited to plots sown with seed inoculated with the organism.

Spread of the disease occurred in a direction down the slope of the ground and along the lines of surface wash.

The implications of the experiment are discussed and proposals made for modifications in technique.
OBSERVATIONS ON THE DESERT LOCUST IN EAST AFRICA FROM JULY, 1928 TO APRIL, 1929
Authors: WILLIAMS C. B.
Published: February 2008

The paper deals with observations made on the desert locust in East Africa in 1928–9. Two broods were observed to develop between May, 1928 and April, 1929. Females slightly outnumbered the males in a number of random collections of adults. A list of plants eaten or avoided by the adults is given including species from 62 natural orders, of which 18 are represented by both edible and inedible species. Notes on the food plants of the hoppers are also included. Hoppers of the IVth and Vth stages were observed to have a maximum speed of about 1/4 mile per hour.

The chief natural enemies seen were Stomatorrhyna lunata, a Dipterous parasite of the egg, and Sphex aegyptiacum, a predator on the adult locusts. The latter had developed a migratory habit and followed its host.

No regular relation between direction of flight and direction of wind was observed.

Trekking activity in swarms of hoppers of the IVth and Vth stages was most noticeable when the air temperature was above 15° C.

Feeding was most general when the air temperature was above 10° C, and in the swarms observed, which were probably short of food, took place at almost any hour of the day.

Continual observation of one band of hoppers throughout a whole day showed that the direction of movement was by no means constant. In fact two complete circles were made in the course of the day.

Adult locusts were found to orientate head towards the sun when the black‐bulb temperature was 130° F. or above.

Adult locusts were found to be insensitive to sounds such as the banging of tin cans (often used for scaring purposes) or the firing of a gun, but were much frightened by the noise of a file drawn down the edge of a saw.

Railway trains were got through swarms of egg‐laying adults on the ground by having several boys running in front of the train at short intervals. This procedure frightened the locusts off the line and was much more successful than any system of brushes in front of the wheels.

A few small‐scale experiments with poisoned bran showed no difference in effectiveness between sodium arsenate and sodium fluosilicate.

A few individuals from a swarm of just hatched hoppers were kept in isolation until the last larval stage, but did not assume the pale colouring of the solitary phase.

Dissections of adult females showed that the ovaries remained small (about 11 mm. long) as long as the locusts remained purple‐brown in colour.
STUDIES IN THE PHYSIOLOGY OF THE VIRUS DISEASES OF THE POTATO
Authors: BARTON‐WRIGHT EUSTACE , MBAIN ALAN
Published: February 2008

The present investigation was concerned with the formation of carbohydrates in healthy and crinkle infected potato plants, and the nature of the sugar or sugars of transport. A series of observations were also made to determine whether there were any differences in the carbohydrate metabolism when a latent virus (paracrinkle) was present in a variety.

The varieties used were Arran Victory for crinkle and President for paracrinkle.

The disease was transmitted by stem‐grafting to our virus‐free units with Irish Chieftain for crinkle and King Edward for paracrinkle. All plants were grown in insect‐proof greenhouses.

A series of experimental runs were then carried out at different times in the season. Samples of laminae and petioles were taken at hourly intervals over nineteen hours for crinkle and at two‐hourly intervals over twenty‐four hours for paracrinkle.

It was found that in the early stages of the disease there was no statistically significant difference between carbohydrate formation in healthy and crinkle plants. The chief differences that were detected were (1) that the percentages of all three carbohydrates that were estimated (hexose, sucrose and starch) were higher in the diseased material than in the healthy, and (2) thatthere was a time lag of approximately two hours between the maximum and minimum points in the crinkle and healthy laminae; the former preceding the latter.

Sucrose was found to be the sugar of transport in both cases.

In the later part of the season, significant differences were discovered in the two cases. Sucrose was found to show a marked accumulation in the diseased laminae, and it was ascertained that this sucrose was formed by the hydrolysis of starch, whereas in the healthy laminae the formation of sucrose was brought about by synthesis from hexose, which in turn was formed from hydrolysis of starch. A certain amount of the sucrose was also discovered to be produced directly from starch.

It was also ascertained that sucrose was still the sugar of transport, but evidence was obtained to show that its passage down the diseased petioles was not so readily effected as in the healthy.

The low yields from crinkle infected potatoes is discussed in the light of these results.

The presence of a latent virus in a variety was shown to produce no significant difference in carbohydrate formation, either at the beginning or the close of the growing season.

This investigation was carried out at the Station of the Scottish Society for Research in Plant Breeding, Corstorphine, Edinburgh, under a scheme financed by the Empire Marketing Board. We would like to take this opportunity of thanking the Director, Mr William Robb, F.R.S.E., and Dr A. Nelson, F.R.S.E., for their helpful criticism in a number of different directions.
ON HOPLOCAMPA FLAVA L., THE PLUM SAWPLY
Authors: MILES HERBERT W. , THOMAS I. , HEY G. L.
Published: February 2008

H.flava L., which now appears to be the species definitely associated with injury to the developing fruits of the plum, is shown to be generally distributed over England and likely to be of economic importance where plums and damsons are grown extensively.

The adults are described and the chief points of difference between H. flava and other British Hoplocampids are mentioned.

The egg is described and figured and a full description of the larva and its various instars is given. The incubation period and larval development are discussed.

The writers are indebted to Mr F. R. Petherbridge, M.A., of the School of Agriculture, Cambridge, for consultation from time to time and for his keen interest in the progress of the investigations.
OBSERVATIONS ON THE FLIGHT MUSCLES OF SITONA WEEVILS
Authors: JACKSON DOKOTHY J.
Published: February 2008

In macropterous weevils of S. hispidula F. marked variation occurs in regard to the development of the muscles of flight, some insects being able to fly while others are permanently flightless. Both forms are widely distributed and may occur in the same locality.

In the flightless insects the histology of the fibrous muscles is entirely different from that of the normal muscle; the discs of the fibrous muscles are reduced in size and the phragmata of the metatergum are suppressed. Forms intermediate betweeen the two extremes occur.

A study has been made of the post‐metamorphic development of the flight muscles in S. lineata, a species which is an excellent flier, and it has been found that in the newly emerged weevils the condition of the flight muscles and their chitinous supports closely resembles that of the abnormal form of S. hispidvla. In S. lineata, however, the normal condition is usually attained a short time after emergence.

The flightless macropterous weevils of S. hispidula may therefore be regarded as individuals in which the normal post‐metamorphic development of the flight muscles and their chitinous supports has been arrested.

In the normal form of S. hispidula it has been found that the muscles of flight usually degenerate during the winter, but in S. lineata they are functional for a much longer period and weevils of this species fly readily in spring.

Evidence obtained by breeding S. hispidula suggests that unfavourable environmental conditions during ontogenetic development may be responsible for the production of the flightless weevils.
EVAPORATION OF WATER PROM APPLES IN RELATION TO TEMPERATURE AND ATMOSPHERIC HUMIDITY
Authors: SMITH W. HUGH
Published: February 2008

A technique has been described for determining by a weighing method the rate of evaporation of water from certain isolated plant organs (apples and pears) under conditions of constant temperature and constant atmospheric humidity.

The rate of evaporation from Bramley's Seedling apples at constant temperature and humidity changes steadily throughout the storage phase; decreasing at first rapidly and then more slowly towards a more or less steady state. It is evident that the rate of evaporation is conditioned by certain internal factors, the nature of which is at present unknown; the magnitude of the control exerted by these factors is observed to change with time. No sharp changes in rate occur during this period, and so far it has not been possible to correlate the smooth transition with phenomena of metabolic activity, such as change in osmotic pressure of the cell solutions.

The relation between evaporation rate and R.H. at constant temperature shows a marked deviation from the linear, as exhibited by a free‐water surface. There is an increase in the rate of evaporation with decreasing R.H. down to about 65 per cent. R.H.; a gradual decline in the rate of increase being shown for each decrement of R.H. The resistance to outward movement of water vapour would therefore appear to change with change of external vapour pressure. Below about 65 per cent. R.H. it would seem that a steady rate might be expected, when internal resistances would become Hmiting.

At constant R.H. and temperatures between the limits of 3 and 15° C. the rate of evaporation is more nearly approximate to the vapour‐pressure deficit of the external atmosphere.

The variation in evaporation rate between individual apples of the same variety under the same conditions of temperature and humidity is considerable. These variations cannot be attributed to differences in the thickness of the cuticles, since a marked negative correlation between evaporation rate and thickness of cuticle was found in Cox's Orange Pippin apples. Other factors such as frequency of distribution and size of lenticels and the structure of the stem and calyx ends of the fruit probably exert a controlling influence over the magnitude of evaporation rate.

The increase in rate of evaporation which occurs with fungal invasion of the tissues would seem to indicate that, although in the healthy fruit some control over the supply of water to the evaporating surface is exerted by the cortical tissues, the extent of this control is small in comparison with that exerted by the epidermis.

Grateful acknowledgment is made to Drs Franklin Kidd and Cyril West for their very helpful criticism and advice, and to Miss Ursula Tetley for her co‐operation.
BIOLOGY AND LIFE HISTORY OF LIMOTHRIPS CEBEAL1UM HALIDAY AND APTINOTHRIPS RUFUS GMELIN FEEDING ON GRAMINEAE
Authors: SHARGA U. S.
Published: February 2008

The insect L. cerealium feeds on wheat and oats and on various meadow grasses in spring and summer.

The method of egg‐laying, hatching, and the habits of adult and immature stages are noted and described.

The total life history from the egg to adult takes 29–35 days; egg period 10–13 days, larval period 13–17 days, pre‐pupal period 2–3 days and pupal period 6–7 days.

L.cerealium has been found to be responsible for non‐setting of seeds in wheat and oats. The character of the injury is described. Laboratory experiments on wheat show that in proportion to infestation the injury to ears is increased.

Males have short life. The fertilised females fly off, after the crop is harvested, and hibernate in grass or other sheltered places during winter. The emergence of adult females from hibernation was about late May in 1930. This species appears to be single brooded here.

In Aptinothrips rufus the method of egg‐laying, hatching, etc., is similar to L. cerealium.

The two forms of this species differing in the number of antennal joints are generally found separate but occasionally mixed up in various proportions. The distribution of the two forms and the ratio collected from various localities are given with number of males, females, and immature stages.

The six‐jointed form is found to contain eggs all through the year and the eight‐jointed form only for a few months of the year. The relationship of the two forms is discussed and it is suggested that there appears to be four races within the species, a sexual and a partheno‐genetic race of each form.

An internal nematode parasite was found in Aptinothrips rufus. The parasite causes sterility in almost all cases. Predaceous Trombidium larvae were also found attached to A. rufus.
The Effect of Soaking in Water on the “Seeds” Of Some Gramineae
Authors: CHIPPINDALE H. G.
Published: February 2008

1. The effect of soaking in water on the subsequent germination of several species of Gramineae has been determined under a variety of conditions.

2. With most species an acceleration of germination results from presoaking, but this may be negligibly small under optimum conditions in the soil.

3. Dryness of soil and a relatively low temperature greatly increase the differentiation between the germination of soaked and untreated seeds. A peculiarly extreme case of such an effect by the second of these factors is provided by Phleum pratense.

4. It is not possible to generalise regarding the behaviour of different species in relation to soaking in water. Closely related species (e.g. Lolium iatalicum and L. perenne, and Festuca pratensis and F. elatior) show considerable differences of behaviour.

5. In none of the species examined is the acceleration produced by soaking so pronounced as is the case in Dactylis glomerata.

6. The acceleration which results from presoaking in Avena sativa is brought about by the start given to the early processes of germination.
On The Pigmy Mangold Beetle (Atomaria Linearis Steph.) and Methods for its Control
Authors: EDWARDS E. E. , THOMPSON J. K.
Published: February 2008

1. An extensive investigation of the Pigmy Mangold Beetle (Atomaria linearis Steph.) on sugar beet and mangold has been made during the past six years, both in the field and in the laboratory

2. The symptoms of attack are given, together with a brief account of the distribution and life history of the beetle.

3. General field observations of infested areas both in Lincolnshire and Shropshire indicate that epidemics of the Pigmy Mangold Beetle in sugar‐beet and mangold crops only occur under certain conditions, of which continuous cropping of the land with susceptible plants is usually considered of primary importance.

4. It is found that environmental factors have a marked influence on the relative susceptibility of sugar‐beet and mangold crops to serious injury by the beetle. Evidence is produced to show that many of these factors are under the direct command of the grower and their significance on control measures discussed.

5. Field experiments on control of the pest show that, of the treatments tested, the use of phenol and magnesium sulphate at the rate of 1 and 5 per cent. respectively, as a seed steep is the most effective.

6. There is reason to believe that the common practice on the Continent and in certain districts in this country of sowing crude naphthalene with sugar beet seed as a deterrent against the Pigmy Mangold Beetle results in serious damage to germination.

7. Different varieties of sugar beet vary in the degree to which they are liable to infestation but the differences are generally small and unimportant. Mangolds, as a rule, are more resistant than sugar beet.

8. In addition to mangold and sugar beet, the beetle is recorded for the first time in Great Britain on garden beet and White Goosefoot (Chenopodium album). Some evidence is presented to show that a rotation of crops as means of control of the beetle may be ineffective in areas where White Goosefoot prevails.
III. Injection for the Diagnosis and Cure of Physiological Disorders of Fruiot Trees.
Authors: Roach, W. A.
Published: February 2008

Water and sand‐culture methd are of somewhat limited applicability to fruit trees.

The interpretation of the results of manurial experiments, whether conducted in the field or in pots, are complicated by base exchange and similar phenomena. Direct injection of solutions into trees is, therefore, suggested an an additional method for studying, and possibly even curing, physiological disorders, especially those of the “deficiency” type. Methods for injecting whole trees, separate branches, with or without their corresponding roots, or separate twigs are described.

Some effects of injection on the vigour of the tree and on disease are mentioned.
COMPETITION IN SEEDS MIXTURES AT HIGH ELEVATIONS (850 FT.) AT MOELGLOMEN, TALYBONT, CARDIGANSHIRE
Authors: THOMAS M. T.
Published: February 2008

The experiment was designed to obtain further information on the value of certain species and strains of grasses and legumes for permanent grass on upland, thin soiled, dry fields of low fertility.

Their ability to compete in mixtures and their persistency were studied in detail and the evidence indicates, in a general way, that these factors operate in rather a different manner on the uplands as compared to the lowlands.

Pedigree cocksfoot is superior in productivity to pedigree perennial rye‐grass, but the need for a small seeding of pedigree perennial rye‐grass to help protect the pedigree cocksfoot during the first few years is suggested.

Montgomery red clover has proved itself to be infinitely better than Lotus major, kidney vetch and wild red clover, especially for hay. Of the bottom grasses in the test, smooth‐stalked meadow grass has been a failure, and although rough‐stalked meadow grass made a fair contribution to the second crop of hay when sown at a heavy seed rate, crested dogstail and the fine‐leaved fescues have been far more aggressive. The heavy contribution of crested dogstail to the second‐year hay crop is worthy of note. The aggressiveness of the fine‐leaved fescues in the aftermath of the third harvest year is a factor to be further considered. Chewing's fescue, in distinct contrast to red fescue (pedigree), gets very winter‐burned and unpalatable.

Wild white clover is an essential constituent in mixtures for these conditions. It is probable that Italian rye‐grass at 10 or even 12 lb. per acre is not too much where the spring grazing is hard and where the fields are not closed for hay until early May. Indigenous and pedigree strains have given more hay, more leaf and have been more persistent than the commercial strains.
PSYLLIA PEREGRIN A FÖRST., THE HAWTHORN RACE OF THE APPLE SUCKER, P. MALI SCHMIDB.
Authors: LAL K. B.
Published: February 2008

Conclusions and Summary

The conclusions based on these investigations may be summarised as follows:

“P. peregrina” and P. mali of hawthorn are identical, and are only the seasonal forms of one and the same species. These insects are also morphologically indistinguishable from P. mali o. apple.

The nymph of the forms occurring on hawthorn is different from the typical nymph of the apple sucker (P. mali), and has long been known as the nymph of “P. peregrina.” In it, however, there occurs a small percentage of variations, in which the characteristic brown longitudinal streak of the wing pads does not occur.

Although morphologically similar, specimens of P. mali of hawthorn and apple do not mate with each other, nor do they oviposit interchangeably on each other's host plants. The nymph of either when transferred to the food plants of the other does not survive very long.

4. P. mali of the apple has a biological race on hawthorn, which has long been known as P. peregrina. This race should be distinguished as P. mali Schmidb. race peregrina, which is the name it is proposed to assipn to it. The two races, in view of their dissimilar nymphs, furnish an instance of poecilogony.
THE EFFECT OF ENVIRONMENTAL CONDITIONS UPON PYRETHRUM (CHRYSANTHEMUM CINERARIAEFOLIUM). I.
Authors: MARTIN J. T. , TATTERSFIELD F.
Published: February 2008

The effect of soil fertility upon the insecticidal value of the flowers has been studied in a series of pot experiments. On heavy soil the pyrethrin I content of the flowers was not increased by the application of fertilisers. The plants produced good yields of flowers, rich in pyre‐thrins, when grown in soil of low fertility.

Under conditions of normal growth and vitality, the extent of production of the pyrethrins in the flowers was characteristic of the individual plant and was dependent upon some factor which appeared to be genetical in character. A plant initially producing flowers of high or low percentage poison content continued to give flowers of the corresponding degree of richness in succeeding years, independently of the application of manures, or apparently of the number of heads produced. Plants derived from rooted shoots produced flowers corresponding in quality with those initially yielded by the parent plant. The insecticidal value of pyrethrum flowers may be improved by plant selection, followed by vegetative propagation.

In the fully open flowers, the complete disc florets contained 90 per cent. of the total pyrethrins present in the flowers, and of this the greater part was found to be located in the ovaries.
THE PHYSICAL ENVIRONMENT OF SCOTTISH AGRICULTURE IN RELATION TO CROP IMPROVEMENT PROBLEMS1
Authors: SNODGRASS C. P.
Published: February 2008

Summary.

The co‐ordination of the available data relating to the environmental conditions of agricultural regions is advocated as a means of facilitating the testing and ultimate distribution of new crop varieties.

The physical environment (topographical, geological, climatic and edaphic) of three agricultural regions is described, and its influence on the length of the growing season, the length of crop rotation, and the distribution of the principal crops is discussed.

Taking the parish as the unit, maps for the three regions are given to illustrate the mean elevation of cultivated land (Figs, 1a, b and c), the estimated accumulated temperatures (Figs. 2a, b and c), the mean annual rainfall (Figs. 3a, b, c and d), the percentage of farm land under rotation (Figs. 4a, b and c) and the length of rotation (Figs. 5a, b, and c).
FURTHER STUDIES ON QUANTITATIVE METHODS WITH TWO PLANT VIRUSES
Authors: SAMUEL GEOFFREY. , BEST R. J. , BALD J. G.
Published: February 2008

Summary.

The arrangement of experiments for intercomparison of a number of virus samples is discussed and the use of randomised blocks or Latin squares, combined in certain cases with half‐leaf comparisons between all samples or against a standard, is recommended.

Improvements in the ground‐glass spatula method of inoculation have been suggested.

Provided there is sufficient inoculum to cover the leaf when the spatula is rubbed over it, the amount, of inoculum makes no difference to the number of lesions produced.

The conditions to which test plants are subjected shortly before inoculation were found to influence the number of lesions produced by a given inoculum.

The number of lesions produced by otherwise similar inocula is influenced by their pH value and electrolyte content. The optimum pH. range for the virus of tomato spotted wilt is very limited (roughly pH 6.0–8.5). Tobacco mosaic virus in a potassium phosphate buffer at a pH value about 7 produced the maximum number of lesions in the concentration range 0.05‐0.2M. It is recommended that for most quantitative work viruses should be buffered at a definite pH value.

When effects due to varying pH value and electrolyte content were excluded, the virus of tomato spotted wilt was still found to be inactivated by certain oxidising agents and preserved by certain reducing agents.
INSECT INJURY SIMULATING FUNGAL ATTACK ON PLANTS
Authors: LEACH R.
Published: February 2008

Summary.

Four different types of disease of the mango tree are shown to be caused by the capsid bug, Helopeltis bergrothi Reut.

Symptoms of a stem canker, an angular leaf spot, a fruit scab and a fruit rot of mangoes are described.

A description of the morbid anatomy of these diseases is given.

References to control measures advocated against H. bergrothi are cited.

A discussion of the results shows the possibility of the importance of further co‐operative work between entomologists and mycologists in the study of plant diseases.