bluuebunny/crossref_metadata_2025 huggingface dataset:
SOIL CONDITIONS AND THE TAKE‐ALL DISEASE OF WHEAT
Authors: GARRETT S. D.
Published: February 2008

Ophiobolus gramini‐s can spread through the soil only along the roots of its host plants. A distinction can thus be made between two phases in the activity of the fungus, a parasitic or ascendant phase, in which the fungus is actively increasing on the roots, and a pseudo‐saprophytic or declining phase, in which the fungus is merely persisting in dead host tissue. In the declining phase, the disappearance of the fungus from the soil must be hastened by the action of the soil saprophytes in actually decomposing its mycelium. Certain soil conditions, which at one time increase the activity of the fungus on the roots of its host, may at another time hasten the disappearance of the resting mycelium from a fallow soil.

The rate of growth of Ophiobolus graminis along the roots of wheat seedlings has been found to vary widely with soil conditions, and growth may even be inhibited altogether. The best growth of all is made in sand; growth in soil increases both with improvement in aeration, and with rise in pH value; it is thus best in light and open soils, and in alkaline soils. In the case of neutral and alkaline soils, growth may be improved by steaming.

A hypothesis has been put forward whereby the rate of growth of the fungus along the roots is related to the concentration of carbon dioxide in the microclimate of the root zone, along which the fungal hyphae are growing. Carbon dioxide is produced by the respiration of the host root, the hyphae of Ophiobolus, and the soil microflora; variation in the concentration of carbon dioxide in the root zone will depend on the rate of diffusion of the gas away from the root. This will be most rapid, on the one hand, in light and open soils favouring rapid physical diffusion, and, on the other, in alkaline soils, which can act chemically as carbon dioxide acceptors. These are just the soil conditions which make for most rapid growth of the fungus along the roots.

Growth of Ophiobolus graminis along the roots is also most rapid under just those soil conditions known to favour the occurrence of the take‐all disease in the field, viz. loose and open soils, soils of light texture, and alkaline soils. This well‐established action of soil conditions upon the prevalence of the disease in the field is thus considered to operate directly through the fungus, rather than indirectly through the resistance, yet to be demonstrated, of the host plant.
THE EFFECT OF VARIOUS CHEMICAL TREATMENTS ON THE ACTIVITY OF THE VIRUSES OF TOMATO SPOTTED WILT AND TOBACCO MOSAIC1
Authors: BEST RUPERT J. , SAMUEL GEOFFREY
Published: February 2008

A. Tomato spotted wilt virus (All tests made with suspensions buffered at pH. 7)

The concentration of active virus units in suspensions of tomato spotted wilt virus stored at 0oC. in a buffer solution of JJH 7 was maintained without loss for 11 hours by excluding free oxygen.

A significant fall in the concentration of active virus units occurred in suspensions treated as in (1) but through which air was bubbled.

At room temperatures the virus underwent fairly rapid inactiva‐tion even in the absence of free oxygen, although the presence of oxygen hastened the inactivation. The rate of inactivation in the absence of oxygen varied from time to time, and it is concluded that this inactivation was due to the presence in the infective juice of some oxidized substance which is usually present in only small but variable amounts, and that it is reduced by those substances (see (4) below) which arrest anaerobic inactivation.

Certain substances added in the reduced form which yield suspensions with an Eh value of +0–1 volt or less at pH 7 arrested the normal anerobic inactivation of the virus. The remarkable preservative action of cystein is discussed.

The virus was rapidly inactivated in vitro by 0–001M solutions of oxidizing agents which induced in the suspensions a potential greater than + 0–2 volt at pH 7. With the exception of methylene blue, oxidizing agents which gave a suspension with an Eh value below +0–1 volt at pH 7 did not inactivate the virus.

The reducing agents referred to in (4) protected the virus against inactivation when exposed to air. This protective effect was not permanent but prolonged the activity of inocula for many hours beyond that of the controls.

The effect on the virus of a number of other substances was also examined. Those having greatest interest are: (a) KCN, which in 0–01 M solution protected the virus both against anaerobic and‐ aerobic inactivation. Its probable mode of action is discussed on the bases of experiments reported, (b) HgCl2, which in 0.001 M solution caused instantaneous inactivation of the virus, (c) Cathecol, quinol and phenol alone inactivated the virus in the presence of air, but did not do so if Na2SO3 was also present. It is concluded that secondary oxidation products caused the inactivation observed.

Attempts to reactivate virus which had been inactivated by exposure to air or by means of HgCl2 were unsuccessful.

It has been shown that the inactivating effects observed are due to an action on the virus itself.
ON THE BIOLOGY OF CERTAIN SPECIES OF HOLCOCNEME1 KON. (HYMENOPTERA‐SYMPHYTA)
Authors: MILES HERBERT W.
Published: February 2008

Four representatives of the genus Holcocneme Kon. occur more or less commonly in Britain.

H. caeruleocarpa Htg. breeds on Salix and Populus. It oviposits in pocket‐shaped incisions in the leaves, and the eggs have an incubation period of 8–9 days. The young larvae are dark with the head black, older larvae are green with the head brown. A typical body segment has six annulets with dorsal setae on the second and fourth and the caudal segment has prominent cylindrical pseudocerci rounded at the apex. Females have five and males have four larval stadia, and pupation takes place in dark brown cocoons in the soil. There are two or three generations during the year, and the insects pass the winter in the cocoons. Parthenogenetic reproduction produces males.

Holcocneme lucida Panz. breeds on species of Prunus and lays its eggs in shallow incisions along the veins on the under surface of the leaves. The incubation period is 7–10 days. The larvae are yellowish green with the head brown. A typical body segment has six annulets of which the second and fourth are setiferous; the caudal segment bears prominent pseudocerci that are broader at the apex than at the base. Females have five larval stadia and males four. Pupation takes place in brown cocoons in the soil. The species is univoltine and parthenogenesis is arrhenotokous.

Holcocneme crassa Fall, is widely distributed in Britain and has been recorded as breeding on Salix, Populus and Rumex. The larvae are green with the head greenish brown and the annulation of the body segments is similar to that of Holcocneme caeruleocarpa. The setae are longer and rather denser than those of H. caeruleocarpa and the pseudocerci are acuminate.

The biology of H. erichsoni Htg. is described from the published accounts of MacDougall, Hewitt and Mangan. The females oviposit in the young shoots of larch; the larvae are greyish green, and though the annulation of the body segments is somewhat similar to that of H. lucida, the caudal segment has no pseudocerci and the arrangement of the setae differs from that of the other larvae described here. Females have six larval stadia. The tough brown cocoons are constructed at the surface of the soil. In Britain the species is thelytokous and parthenogenetic reproduction produces females.

The differences in the biology of the species and in the form and structure of their larval stages, together with differences in the structure of the adults and the nature of parthenogenesis suggest that the limits of the genus Holcocneme Kon. may not yet be adequately defined.

I am greatly indebted to Mr Benson for specimens of Holcocneme crassa; to Mrs Mary Miles, M.Sc, for assistance in the rearing of the larvae, and to Mr Morris Cohen, M.Sc, for help in the preparation of the text‐figures.
STUDIES ON 08CINELLA FRIT LINN
Authors: CUNLIFFE NORMAN
Published: February 2008

As the result of studies on Oscinella frit during the years pro to 1928, it was considered that an attempt might be made to solve economic problem presented by this fly by hybridization of oats, i a resistant variety as one parent.

The technique adopted is described and the experimental data show that resistance to attack is an inheritable character (or complex characters), although difficult of precise measurement. Further, shown that agricultural quality and resistance to attack are not in patible.

Wet weather conditions during the flight of the fly have a marked effect in limiting the extent of damage to the crop.

It is suggested that varietal differences in extent of attack ma due to varietal differences in crude fibre production or depositio silica, both tending to increase the larval difficulties and there for resistance of the plant.

I have great pleasure in acknowledging the readiness with w Dr Hunter of the School of Agriculture, Cambridge, has given me benefit of his experience; also, the valuable criticism which Mr J. C. F. Fryer, of the Ministry of Agriculture Pathological Laboratory, Har‐penden, has always placed freely at my disposal.
SHEEP BLOW‐FLY INVESTIGATIONS III. OBSERVATIONS ON THE CHEMOTROPISM OF LUCILIA SERICATA MG
Authors: HOBSON E. P.
Published: February 2008

The attraction for Lucilia sericata Mg. of putrefying substances, when placed on sheep, seems to be due largely to the presence of indole, skatole and ammonium carbonate. When dilute solutions of these compounds are placed in the fleece of live sheep, L. sericata females are attracted to oviposit. This represents an important advance since standardized attractant solutions are now readily available.

A technique for testing repellents has been devised which is based on this tropism. The method appears to be critical and is rapid, each test requiring only 2 hours; it should be especially valuable for selecting likely repellents for further investigation.

Sheep vary considerably in their attractiveness for L. sericata; this may be an important new factor in the susceptibility of sheep to blow‐fly attack. The attractiveness of individual sheep can readily be measured with solutions of indole and ammonium carbonate.

I am greatly indebted to the Agricultural Research Council for a grant which has entirely financed this work. I wish to express my appreciation to Dr W. M. Davies for his helpful advice and active interest in this work.
SHEEP BLOW‐FLY INVESTIGATIONS IV
Authors: HOBSON R. P.
Published: February 2008

An investigation has been made of the distribution of yolk over the fleece of Welsh sheep.

The suint content of the wool is relatively low on the back and high on the flanks and breast. The distribution of suint over the back appears to vary in a random way.

The pR of water extracts generally runs parallel with the suint content of the wool, although the correlation is not mathematically significant. The reaction is approximately neutral on the back and alkaline on the flanks and breast.

The grease content is fairly uniform over the back and flanks, but the wool on the breast contains relatively less grease.

These results are discussed in relation to Holdaway and Mulhearn's theory that sweat content is an index of susceptibility to blow‐fly attack.
THE PROBLEM OF THE EVALUATION OF ROTENONE‐CONTAINING PLANTS
Authors: TATTERSFIELD F. , MARTIN J. T.
Published: February 2008

A study has been made of the rotations of the resins from three types of derris root, and of a fraction rich in toxicarol separated from two of them. No strictly quantitative relationship between their rotations and their toxicities to Aphis rumicis has been found. The addition of caustic potash in methyl alcohol to the benzene solutions of the resins induces a characteristic change from laevo‐ to dextro‐rotation in the samples rich in toxicarol. The induced dextro‐rotation then declines in value with time. This effect is shown by the “toxicarol” resin. The rate of the decline is accelerated by increasing the amount of methyl alcohol.

We are greatly indebted to the Copper Technical Bureau for gifts of the “Sumatra‐type” root and of resins derived from this strain.

We wish to express our thanks to Mr C. Read for help during the course of this work.
THE CONTROL OF BLIGHT (PHYTOPHTHORA INFESTANS) IN SEED POTATOES BY TUBER DISINFECTION
Authors: GREEVES T. N.
Published: February 2008

During storage the loss in seed potatoes through blight (Phytophthora infestans) is often severe if the crop is lifted while the fungus is sporulating on the haulms. It has been shown that this loss may be prevented by the disinfection of the tubers immediately after digging.

The best results have been obtained when the disinfection was carried out on the same day as digging, immediately after the crop was lifted. Disinfection 3 or 4 days after digging gave little or no control of the disease.

Both methods of disinfection employed, a 90 min. steep in a 01 per cent solution of mercuric chloride and an instantaneous dip (30 sec. to 1 min.) in a solution of a proprietary organic mercury compound, gave satisfactory results.

Disinfection had no injurious effect on the subsequent sprouting of the tubers.

The practice of “greening” the tubers is not likely to give any control of blight when wet weather follows digging.
THE USE OF NUMBERS OF INFECTIONS FOR COMPARING THE CONCENTRATION OF PLANT VIRUS SUSPENSIONS: DILUTION EXPERIMENTS WITH PURIFIED SUSPENSIONS
Authors: BALD J. G.
Published: February 2008

An equation was developed to describe the relation between the numbers of infections given by inoculation of host plants with virus suspensions and the relative concentration of the suspensions. It was of the form y=N (1‐e‐m), where y was the number of infections, N the maximum possible number of infections, e the base of natural logarithms, and m the ratio of virus units entering and causing infection to the total number of entry points, leaves, or plants (according to the unit used for judging infection).

The function m was expanded for the particular case of dilution experiments.

Methods of fitting the data obtained from dilution experiments were discussed.

The data from seven dilution experiments with carefully purified samples of four viruses (infections reckoned as lesions) were fitted with equations of the form given above, and were found to agree fairly well with the calculated values.

Two types of distortion in the dilution series were illustrated.

The significance of the maximum N was discussed.

The same data with y as the number of leaves infected were found also to agree with the equation.
A NEW VIRUS OF MAIZE TRANSMITTED BY CICADULINA SPP
Authors: STOREY H. H.
Published: February 2008

The occurrence in East Africa is recorded of a virus producing a transitory diffuse mottling in maize. The symptoms are distinguishable from those of other viruses known to affect this plant.

The mottle virus is transmitted by active races of the same species of Cicadulina that transmit the streak virus. Insects of an inactive race usually fail to transmit, although rare exceptions have been encountered.

The presence of one virus in a plant does not prevent the development of the other, nor are the ultimate symptoms of one affected by the other. In some circumstances, however, the mottle virus may cause a significant delay in the development of the symptoms of streak disease. The presence of one virus in an insect does not prevent it from taking up and transmitting the other.

The mottle virus is regarded as a new one, unrelated to that of streak disease.
THE BIOLOGY OF THYSANOPTERA WITH REFERENCE TO THE COTTON PLANT: THE RELATION BETWEEN VARIATIONS IN TEMPERATURE AND THE LIFE CYCLE
Authors: MacGill ELSIE I.
Published: February 2008

The exposure of larvae of Thrips tabaci to temperatures of 38, 31, 8 and—4° C. for periods varying from 1 to 96 hours has a marked effect on the survival of the insects.

At 100 per cent relative humidity exposure to 38 and 31° C. gives a higher rate of mortality than exposure to 8 and—4° C.; at 82 per cent relative humidity 38 and—4° C. are the least favourable temperatures, and at 75 per cent relative humidity—4° C. is the most unsuitable for the survival of the insects.

In some conditions more larvae survive after a long exposure than after a shorter one, which suggests that at certain points in their life cycle the insects are particularly sensitive to changes in their environmental conditions.

From these experiments it does not appear that relative humidity has a marked effect on the length of the life cycle.

Exposure to low temperatures has a more constant effect on the length of the larval stage than exposure to high ones; exposure to—4° C. retards development for a longer time than the duration of the exposure, and exposure to 8° C. for a shorter time.

The length of the life cycle varies with the absolute humidity of the atmosphere, and at vapour pressures below 15 mm. the conditions have a retarding influence on development, while those between 15 and 25 mm. accelerate development.
THE CONNEXION BETWEEN THE KEEPING QUALITIES OF COMMERCIAL VARIETIES OF ONIONS AND THE RATES OF WATER LOSS DURING STORAGE
Authors: WOODMAN R. M. , BARNELL H. R.
Published: February 2008

From the results for the onion varieties examined it is demonstrated that high relative rates of water loss and high total water losses are characteristic of non‐keeping types. This is so especially in the period immediately succeeding harvest, and the argument is therefore put forward that actual keeping tests are unnecessary when classifying, for example, new lines as keepers and non‐keepers.
VIRUS DISEASES OF THE POTATO: THE “CARRIER” PROBLEM. ITS RELATION TO SYMPTOMATOLOGY AND COMMERCIAL POTATO GROWING
Authors: WHITEHEAD T.
Published: February 2008

Symptomatology, of which a study of “carriers” is regarded as one aspect, tends to be used as a means of segregating “unit” viruses rather than as a means of furthering plant physiological studies. The effects of changes in environmental conditions of growth, acting through the unstable metabolism of a plant upon a virus, have not been adequately studied. Until this is done, the specificity of the reactions said to be due to a unit virus must remain in doubt and, with it, the whole foundation of the biological methods of segregating viruses.

The symptomatological unit is the plant cell, and the clinical picture resulting from infection is the expression of the varying degree to which invaded cells dominate, or are dominated by, a virus. Successive stages in plant dominance are shown by (a) discontinuous or local symptoms; (b) symptomless shoots; (c) individual carrier plants in a variety usually reacting to infection; (d) carrier varieties.

The conditions under which the power to suppress symptoms can be broken down are discussed. Masked symptoms are revealed by relatively slight environmental changes, but the breakdown may be the more difficult to achieve as perfect “carrying” is approached. There is no fundamental difference between “masking” and “carrying”. The conditions under which masking can be converted into carrying are also discussed.

Evidence is submitted to show that a perfect carrier plant is not only unaffected in vigour as a consequence of carrying a virus, but may thereby exhibit a reduced susceptibility to certain other viruses in the field.

Field trials are described in which proof is given that the viruses carried by the varieties King Edward VII (paracrinkle), and Up‐to‐Date (streak and virus X), were not transmitted to intolerant varieties under the most favourable conditions. These carrier varieties are not therefore the serious menace to other varieties they are commonly believed to be.
METHODS OF INVESTIGATING THE BIONOMICS OF THE COMMON CRANE‐FLY, TIPULA PALUDOS A MEIGEN, TOGETHER WITH SOME RESULTS
Authors: BARNES H. F.
Published: February 2008

Full‐grown larvae of Tip & paludosa Meigen were obtained by application to the soil of an emulsion of orthodichlorobenzene, and it is suggested that the larvae become non‐susceptible to this treatment about 6 weeks before pupation. The larvae were reared in pota of soil containing germinating and growing wheat.

The adult crane‐flies were kept in glass tubes for longevity trials which showed that on the average the males lived about 7 and the females 4–5 days. Mating and oviposition took place in these tubes.

Twenty‐seven females laid 5408 eggs, averaging 200 each. About 45 per cent of the eggs were laid the day the female emerged and 40 per cent the fist day after. It is believed that these figures are too low as the regular observations stopped a t 7 p.m. G.S.T. and it is suggested that 75 per cent of the eggs are in reality laid by midnight on the actual day of emergence and 10 per cent on the first day after. The eggs were kept damp in solid watch‐glasses which xere stood in water in culture dishes.

It is shown that by the time the peak of crane‐flies on the wing has been reached, the peak of eggs in the soil will already have been passed.

Hatching took place 11–15 days after the emergence of the parent crane‐fly, 2498 hatching from 5408 eggs. The young larvae were kept in Petri dishes and fed on wheat rootlets, clover or chickweed leaves, pieces of cabbage leaves, slices of potato or bran. By the time the 3rd instar was reached about 54 per cent mortality had occurred, chiefly owing to larvae escaping and cannibalism (576 survived out of 1257). This stage was reached in roughly 14 days.

The breeding potential was as follows: 51 per cent of the nearly full‐grown larvae emerged as adults (this figure is low because of the number of larvae escaping); 75 per cent of the available eggs were laid by the females; 46 per cent of the eggs laid hatched, and 46 per cent of the larvae survived the fist two instars. In other words, under the conditions of the experiment, on the average, one female crane‐fly laid 200 eggs, 92 larvae hatched and 44 survived the first two instars.
ADDLED BROOD OF BEES
Authors: TAER H. L. A.
Published: February 2008

Addled brood is produced by defective queen bees and is not of a contagious nature as are the other common brood diseases.
STUDIES ON AMERICAN FOUL BROOD OF BEES: THE RELATIVE PATHOGENICITY OF VEGETATIVE CELLS AND ENDOSPORES OFBACILLUS LARVAEFOR THE BROOD OF THE BEE
Authors: TARR H. L. A.
Published: February 2008

Vegetative cells ofBacillus larvaehave not produced American foul brood in healthy nuclei even when B dose almost 3000 times greater than an inoculum of spores of this organism capable of causing the disease has been sprayed over the developing brood.

A very much smaller inoculum of the spores of B.larvaeis effective in producing American foul brood when the developing larvae of healthy nuclei are sprayed directly with them than when they are fed in syrup to the bees.
A BIOLOGICAL STUDY OF THE FUMIGATION OF EMPTY WAREHOUSES WITH HYDROGEN CYANIDE AND ETHYLENE OXIDE
Authors: POTTER C.
Published: February 2008

An account of the fumigation of a number of empty warehouses is given. The fumigation was designed to kill the hibernating larvae of Ephestia elutetta Hb. and Plodia interpunctella Hb. which were present in the fabric of the warehouse. The first sheds were fumigated with “Etox” (ethylene oxide with 10 per cent carbon dioxide), the rest with hydrogen cyanide. An account is given of the factors involved in making a biological test of a fumigation. The effect of the fumigation was studied first by its action on test insects placed in various positions in the warehouse and secondly by an examination of the warehouse to discover how the insects present in situ had been affected. The actual measured concentrations of fumigant are given for the positions where insects were examined. The results are given of a laboratory experiment on the action of hydrogen cyanide on the hibernating larvae of Ephestia elutell and Ploaia interpunctella which amplify the results obtained in the warehouse. An analysis of the results obtained is given together with a summary of the results of other workers.

The work here reported was done under the direction of Prof. Munro, in whose department it was carried out. The writer is greatly indebted to Messrs Page & Lubatti for much helpful criticism and advice and for permission to use their figures of gas concentrations.
OBSERVATIONS ON THE EFFECT OF MOLYBDENUM ON PLANTS WITH SPECIAL REFERENCE TO THE SOLANACEAE
Authors: WARINGTON KATHERINE
Published: February 2008

Summary

In view of the similarity between certain cytological changes induced by virus disease and treatment with molybdenum, pot‐and water‐culture experiments were carried out to determine further the effect of this element on plant growth. Sodium molybdate was used throughout.

Toxic symptoms were produced with the larger dressings of molybdate, injury being shown at much lower concentrations in solanaceous species than in barley.

The shoots of tomato and Solanum nodiflorum turned a golden yellow, and potato tubers a reddish yellow colour when the plants were grown with the larger quantities of molybdate.

These colour changes were shown to be due to the presence of yellow globules of a tannin‐molybdenum compound which had formed within the tissues.

Blue granular accumulations occurred in large numbers in molybdenum‐treated plants. Their distribution was confined to tissues that contained anthocyanin pigment, and their composition was apparently of an anthocyanin‐molybdenum nature.
A STUDY OF CROWN RUST, PUCCINI A CORONATA CORDA, IN GREAT BRITAIN: PHYSIOLOGIC SPECIALIZATION IN THE UREDOSPORE STAGE1
Authors: BROWN M. R.
Published: February 2008

Summary

Uredospore cultures of Puccinia coronata Corda were established in the greenhouse, on their appropriate hosts, by inoculation with uredoor aecidiospores collected in the field. Their pathogenicity was tested by inoculating the uredospores on to a series of grass genera and oat varieties.

Seven varieties of P. coronata have been distinguished in Great Britain:

All these varieties have previously been identified on the continent of Europe and some have been identified in North America.

Some varieties are confined to a single host genus; others infect several genera.

Four physiologic races were distinguished in the var. avenae: race 6, previously identified in North America and Australia, and races 42, 43 and 44, hitherto undescribed. Races 6, 42 and 44 were obtained in Great Britain and race 43 in Portugal.

Experiments carried out under different conditions of temperature and illumination showed that variation in these conditions had only a slight influence upon the infection type produced.

Marked variation in reaction to the rust was shown by plants of the same species of grass inoculated with the same culture under identical conditions. This was probably due to genetic impurity of the grasses.

There were no clear‐cut differences, either in morphological or pathological characters, between the varieties assigned by Klebahn to P. coronata Kleb. and those assigned to P. coronifera Kleb. (P. Lolii Niels.).
STUDIES ON EUROPEAN FOUL BROOD OF BEES: FURTHER EXPERIMENTS ON THE PRODUCTION OF THE DISEASE
Authors: TARR H. L. A.
Published: February 2008

Summary

Evidence has been submitted which supports the theory that European foul brood is a single disease caused by Bacillus pluton White. The course of the disease can be modified by introducing cultures of certain secondary invading bacteria into colonies of bees infected with B. pluton.

A certain “mass inoculum” of B. pluton organisms is required to induce the disease in healthy colonies.

The causal organism is present in virulent form in the rectal ampullae of young bees in affected colonies, but does not appear to exist elsewhere in the bee or to multiply in its intestinal tract.

It appears as if B. pluton is a strict parasite which will only multiply in the intestines of young larvae.
SHEEP BLOW‐FLY INVESTIGATIONS: CHEMOTEOPIC TESTS CARRIED OUT IN 1936
Authors: HOBSON E. P.
Published: February 2008

Summary

An account is given, of tests on 42 organic substances as repellents for the sheep maggot fly, Lucilia sericata Mg. Repellency was measured by observing the ability of added substances to counteract the attraction of a solution of ammonium carbonate and indole placed in the fleece of a sheep. The substances tested were classified into three groups: (a) repellent at 0.3 per cent (amount added to attractant solution), (b) repellent at 0.9 per cent, (c) not repellent at 0.9 per cent. No substance was found which was repellent at 0.1 per cent.

Examination of blow‐flies (L. sericata) trapped when approaching sheep treated with indole and ammonium carbonate, showed that only gravid females are attracted. This chemotropic response depends, therefore, not only on the species, but also on the sex and physiological condition of the fly.

The writer wishes to take this opportunity of thanking the Agricultural Research Council for a grant which has entirely financed this work.
NOTES ON THE VIABILITY OF BACILLUS SALMONICIDA EMMERICH AND WEIBEL
Authors: SLACK H. D.
Published: February 2008

Summary

Observations on Furunculosis of Salmonidae caused by Bocillus salmonicida in brown trout in part of a Hampshire river, over a period of 5 years, showed that the disease was endemic in the area and the epizootics occurred at regular intervals; following spawning and when the water temperature became optimal for the development of the parasite.

While no direct evidence has been found for supposing that the disease was maintained within this area, by living hosts other than salmonid fishes, the possibility that B. salmonicida remains viable for extended periods in natural waters and silt deposits has been investigated.

The results of this investigation tend to show that B. salmonicida can only remain viable in such media when their normal flora and fauna is absent or greatly reduced and that this fact may explain the inconsistency between the observations of Williamson and Plehn on the viability of this bacillus.
A FURTHER NOTE ON FUNGUS ASSOCIATION IN THE SIRICIDAE
Authors: CARTWRIGHT K. St G.
Published: February 2008

1. Earlier work on the association of Sirex cyaneus with a Basidiomycete fungus has been confirmed. The culture of the fungus closely resembles, but is not identical with that of Stereum sanguinolentum; it is therefore thought that it is a form of S. sanguinolentum.

2. The fungus isolated from Sirex gigas has been identified as Stereum sanguinolentum.

3. At the moisture content favourable for the development of the larvae, only slow development of the fungus can take place. Under more moist conditiona viporous fungus growth occurs, with apparently fatal results to the lam.

4. The fungus is introduced into the wood during ovipition in the cam of both Sirez cyaneus and S. gigaa.

5. Fungus was found to be present in glands at the base of the ovipositor in lete stage female pupae.

6. A fungus, the culture of which resembles in appearance that of Daldinia con‐centriea, has been related from larval tunnels and from glands in adult females of Xiphydia prolongata.
CROSS‐AND SELF‐FERTILITY IN SAINFOIN
Authors: THOMSON J. R.
Published: February 2008

1. The number of flowers per raceme is slightly greater in Common than in giant sainfoin.

2. Little more than half the flowers set seed under conditions of open pollination.

3. When the flowers were protected and left untouched the self‐fertility was found to be 0.98%. When the flowers were artificially self‐pollinated by tripping the self‐fertility was significantly higher, being 5.11%

4. Seedlings grown from selfed seed showed poor establishment and reduced vigour.

5. Evidence is brought forward which suggests that the phenomenon of seeding year flowering in common sainfoin cannot be due to the fertilization of the parent plants by pollen from giant sainfoin.

Thanks are due to the following seeds merchants who supplied samples of seed: Dunn's Farm Seeds, Ltd., Salisbury; Gartons, Ltd., Warrington; A. G. Leighton, Ltd., mtchurch; Sutton and Sons, Ltd., Reading.
INVESTIGATIONS ON THE RUST OF ROSES PHRAGMIDIUM MUCRONATUM FR.
Authors: WILLIABIS P. H.
Published: February 2008

1. Cross‐inoculation experiments have shown that Rosa laxa and certain varieties of R. canina are not attacked by Phragmidium mucronatum from the cultivated rose, and that the rose is resistant to certain forms of the rusts on briars.

2. These differences are correlated with differences in the size of the teleutospores.

3. The teleutospores of P. mucronatum require exposure to winter conditions before they will germinate.

4. The mycelium of the rust may persist for several years in the stem but there is no evidence of systemic infection.

The writer is indebted to Mr Courtney Page for supplying material and for much valuable information, and to Dr W. F. Bewley for helpful criticism and advice.
ON THE CHANGES IN CHEMICAL COMPOSITION ASSOCIATED WITH LARVAL DEVELOPMENT IN THE SHEEP BLOWFLY
Authors: RAINEY R. C.
Published: February 2008

The most marked change in composition during embryonic development is the disappearance of fat typical of cleidoic eggs.

The chorion probably consists of protein together with gome nitrogen‐poor constituent, perhaps a saturated fat or wax; chitin and other carbohydrates are absent, and ash and moisture contents are low.

No great changes in composition occur during the first two larval instars, with the exception of a possible utilization of some reserve protein and carbohydrate while the larvae are establishing themselves on the meat.

During the third and last instar, however, a considerable ieduction in moisture content occurs, and an extensive storage of fat takes place, beginning at about the stage at which previous work had shown a marked increase in resistance to starvation. There is also evidence for the accumulation of a large bulk of reserve protein and a smaller amount of reserve carbohydrate during this instar.

The most important factor influencing the degree of uneaturation of the larval fat appears to be the nature of the food fat; iodine values show little variation with the state of development, and preliminary observations suggest that the influence of the environmental temperature is small.

I wish to record my sincere thanks to Prof. P. A. Buxton for his active interest in this work, and to Dr V. B. Wigglesworth for helpful advice and valuable suggestions. I am also indebted to the Agricultural Research Council for the award of a Research Scholarship which has entirely financed this investigation.
INVESTIGATIONS UPON THE CONTROL OF OAT SICKNESS BY THE ADDITION OF CERTAIN CHEMICAL SUBSTANCES TO SOIL INFECTED WITH HETERODERA SCHACHTII SCHMIDT
Authors: EDWARDS E. E.
Published: February 2008

An account is given of pot experiments carried out in triplicate in 1936 and 1937 upon the control of the oat sickness associated with the Root eelworm, H. schachtii. Calcium cyanamide, sodium nitrate, ferrous sulphate, ferric chloride and two forms of ferric oxide were incorporated intimately with infected soil, and quantitative observations were made on the effects of the treatments upon oats grown in the soil in 1936 and

1937 with regard to (a) germination, (b) vegetative growth, (c) panicle production and yield of grain, and (a) degree of infestation of the roots by the nematode. The data obtained show that while all the dressings produced better growth of the plants, at least in the first year after application, calcium cyanamide alone yielded significant results. Further, of the treatments tested, only the use of calcium cyanamide at the rate of as much as 100 cwt. to the acre protected the plants completely from oat sickness in both years and, at the same time, apparently eradicated the parasite from infected soil. Unfortunately, such heavy dressings are not a practicable proposition except, perhaps, under special circumstances.
A STUDY OF CROWN RUST, PUCCINI A CORONATA CORDA, IN GREAT BRITAIN
Authors: BROWN M. R.
Published: February 2008

Summary

Experiments were carried out to determine the relationship between the varieties of Puccinia coronata Corda previously isolated in Great Britain and the two species of Rhamnus, R. Frangula and R. cathartica, which are the alternate hosts of the rust in this country.

The experiments included: (a) the inoculation of seedling plants of the Rhamnus species with sporidia from germinating teleutospores of the different varieties; and (b) the inoculation of a number of grasses with aecidiospores collected in the field on the two species of Rhamnus.

The varieties were found to show a considerable degree of specialization in their relation to the alternate hosts, vars alopecuri, arrhenatheri, avenae, festucae, holci and lolii producing aecidia on R. cathartica only and var. calamagrostidis on R. Frangula only.

The difference in aecidial host relationship of the varieties is not considered to be an adequate criterion for species differentiation, and it is suggested that the use of the names Puccinia coronata Kleb. and P. coronifera Kleb. (P. Lolii Niels.) be discontinued and the rust be designated by the original name P. coronata Corda.

The pathogenicity of the varieties was not altered appreciably by passage through the alternate host and the varieties did not appear to hybridize readily.
SOIL CONDITIONS AND THE TAKE‐ALL DISEASE OF WHEAT
Authors: GARRETT S. D.
Published: February 2008

Summary

Attempts to produce infection of wheat seedlings by the ascospores of Ophiobolus graminis in a variety of natural soils and in sand have failed. Yet, the ascospores germinate well on nutrient agars, and the resulting agar cultures produce infection as readily as cultures obtained from mycelium.

Ascospore infection of sterile wheat seedlings growing in sterilized soil may be obtained without difficulty. The nutrients present in sterilized soil are unnecessary for the initiation of ascospore infection, which occurs as freely as in sterile sand. Ascospore infection is, therefore, considered to be inhibited in unsterilized soils and sand by the antagonism or competition of other soil micro‐organisms.

In unsterilized sand this antagonism is not sufficient to hinder infection by agar inoculum, nor does it appreciably impede the progress of infection along the roots. It is suggested, therefore, that microbiological interference with the initiation of ascospore infection is a competitive rather than an antagonistic effect, and is due to assimilation by the general soil microflora of the nutritive substances excreted from the growing and developing roots. Only under sterile conditions is this organic detritus available to the germinating ascospores.

The results of these experiments render it unlikely that the ascospores can play any part in the survival and dispersal of the fungus under field conditions.
CONIOPHORA PUTEANA (SCHUM.) KARST. ON LIVING SEQUOIA GIGANTEA
Authors: MACDONALD J. A.
Published: February 2008

Summary

When a 36‐year‐old tree of Sequoia gigantea was felled it was found to have rotted areas in the wood at the base of the trunk.

One organism only was isolated from wood in these rotted areas.

The general and detailed microscopic characters exhibited by this fungus in culture identify it as Coniophora puteana.

In the present case it seems clear that the fungus was acting as a primary parasite.
ENCHYTRAEID WORMS AND THE BACTERIA BED METHOD OP SEWAGE TREATMENT
Authors: KEYNOLDSON T. B.
Published: February 2008

SUMMARY OF PARTS I AND II

The flora and fauna of the bacteria bed of a sewage plant are described, and their interrelationships discussed.

A definite cycle in the character and quantity of the Phormidium (Cyanophyceae), the main constituent of the surface growth, is described, the most striking feature of the cycle being the spring off‐loading.

The Enchytraeid worm, Lumbricillus lineatus Mull., is briefly described and its habits observed in relation to the conditions in the bed. The worms feed primarily on the growth of Phormidium, and consequently tend to cluster at the surface, when this is abundant and climatic conditions allow. Cold drives them slightly down, but the off‐loading sends them deeply into the bed, when an increased proportion pass out with the effluent. Drying of the surface in summer sends them down in an erratic manner according to the degree of desiccation.

The cause of the off‐loading of the surface growth in spring is its change from a leathery to a spongy condition. The worms are mainly responsible for this and, therefore, for the off‐loading. The alga rapidly re‐forms (3–4 weeks) upon the pebbles, worms migrating into it again when it is sufficiently thick. The absence of an off‐loading in summer when the growth is again spongy is attributed to the higher rate of regeneration owing to increased temperature and sunlight, which lessens the effect of the worm depredations.

The importance of Lumbricillus lineatus in keeping open a bacteria bed and helping to maintain its efficiency is proved by means of experimental beds. Worms introduced into an inefficient bed with solids rapidly accumulating cleared the medium and allowed active nitrification to commence. If the bed is very badly choked and septic, the worms may be unable to carry out this function. It is probable that all the larger scouring organisms abundant in the bed have this property to a greater or lesser extent.

The mechanism of the spring off‐loading is discussed with special reference to the role of L. lineatus in the Leeds bacteria beds.

The importance of the maintenance of the biological balance by means of the most economic fauna is pointed out.

Finally, the need for more intensive physiological studies is stressed.
STUDIES IN FRUIT STORAGE. I. INFLUENCE OF THE STAGE OF MATURITY AND STORAGE TEMPERATURE ON RESPIRATORY DRIFTS DURING THE RIPENING OF TOMATO FRUITS
Authors: SINGH B. N. , MATHUR P. B.
Published: February 2008

Summary

The growth curves obtained by plotting successive fresh as well as dry weights are of the usual sigmoid type. The percentage of dry matter is the highest in young fruits and thereafter declines and remains fairly constant during maturity and ripening of fruits. The respiration curve during the growth of the fruits shows two high values separated in time: one is initial and represents a high rate of respiration in young fruits, while the other occurs at the onset of senescence.

Irrespective of the stage of ripening at picking, winter‐grown tomatoes show the usual “climacteric” rise during the colour change from orange to red. In certain tomatoes there was no evidence of the occurrence of the climacteric, though the sequence of colour change from green through yellow and orange to red was of the usual type.

The storage life of the fruits is longest at 5·7 followed by 9·8 and 14·7°C. At a given temperature the storage life is longest in fruits picked green as compared to those picked in the yellow and orange stages.

The respiration curves obtained in fruits after transference from low to high temperatures are divisible into two parts: (i) high R.Q. associated with a rapidly falling respiration intensity, and (ii) a value of R.Q. approximating to unity accompanying either a falling or a steady respiration rate.
INTERACTION OF SOIL MICRO‐ORGANISMS WITH OPHIOBOLUS GRAM IN IS SACC, THE FUNGUS CAUSING THE TAKE‐ALL DISEASE OF WHEAT
Authors: LAL AKSHAIBAR
Published: February 2008

Summary

Isolations of Ophiobolus from infected wheat roots gave the maximum percentage of recovery 2–4 weeks after inoculation. Later the percentage of recovery declined. Disappearance of Ophiobolus mycelium was most rapid in acid soils, and slower in sand and in alkaline soil. In soils of more normal type an intermediate behaviour was shown.

From such infected roots a large number of soil fungi and bacteria were isolated and, in part, identified. It is suggested that disappearance of Ophiobolus mycelium from invaded roots is conditioned by the activity of these contaminants, and more particularly of such species as Trichoderma lignorum. Long persistence of the parasitic mycelium in roots growing in sand suggests that this is a poor medium for the growth of micro‐organisms.

A systematic study in plate cultures of the interaction between Ophiobolus and the various soil contaminants isolated showed various degrees of interference with the growth of the former. These effects are described and tabulated. Similar interference effects were seen when Ophiobolus was grown in sterilized soil which had been inoculated with each of the contaminants.

These effects of the living contaminants can, to some extent, be reproduced by their metabolic products, viz. by filtered cultural solutions in which these organisms have grown. The inhibiting or retarding effects so produced are not due to the abstraction of food substances but to the presence of deleterious metabolites. In certain cases it was shown that Ophiobolus mycelium when exposed to such metabolic products was killed. This result was established both by cultural and pathogenic tests.

Tests with wheat seedlings planted over Ophiobolus mycelium, with or without the simultaneous presence of the various contaminating organisms, showed that the antibiotic effect varied from no appreciable effect to complete inhibition of attack. The various organisms are divided into three groups on this basis.
STUDIES EST BACTERIOSIS. XXIV: STUDIES ON A BACTERIUM ASSOCIATED WITH LEAFY GALLS, FASCIATIONS AND “CAULIFLOWER” DISEASE OF VARIOUS PLANTS. PART ILL FURTHER ISOLATIONS, INOCULATION EXPERIMENTS AND CULTURAL STUDIES1
Authors: LACEY MARGARET S.
Published: February 2008

Summary

Bact. fascians (Tilford), the causal agent of fasciation of sweet peas, leafy galls, etc., has been isolated from abnormal growths on plants of twenty‐five different genera belonging to sixteen families, including both Monocotyledons and Dicotyledons.

All these strains of Bact. fascians were inoculated on to sweet pea seedlings which, in the majority of cases, became severely fasciated.

Characteristic galls have been produced on chrysanthemums, carnations, Schizanthus sp., Nicotiana sp., Heuchera sanguinea, petunia, Asparagus sprengeri, Pisum sativum, Phaseolus vulgaris and Vicia Faba by inoculation with various strains of Bact. fascians. No distinct biological variations among the strains could be detected.

Inoculation of gladiolus, tomato and potato gave negative results.

The galls are invariably produced in the region of bud tissue. In young growths the bacteria are mainly confined to the exterior of the galls.

The organism may be carried on the seeds of Schizanthus.

A study of the physiological reactions of forty strains of Bact. fascians has failed to disclose any means by which virulent and a virulent strains can be distinguished in culture.
LETTUCE MOSAIC
Authors: AINSWORTH G. C. , OGILVIE L.
Published: February 2008

Summary

Previous records of lettuce mosaic are cited. The symptoms of the disease on lettuce are described, and the variation in the reaction of different varieties of cabbage lettuce indicated. The host range is extended to certain composite weeds (including groundsel, Senecio vulgaris) and to members of the family Leguminosae (Pisum sativum. Laihyrus odoratus). Experiments in which the virus was seed transmitted through lettuce to the extent of about 6 % are described, and the results of experiments with aphis vectors reported. An account of field observations on the influence of the weather on the disease is given. Certain properties of the virus are described and the status of the virus is discussed. Control measures are suggested.
A GAMASID MITE (TYPHLODROMUS THRIPSI N.SP.), A PREDATOR OF THRIPS TABACI LIND.
Authors: MACGILL ELSIE I.
Published: February 2008

Summary

Typhlodromus thripsi n.sp., of which a description is given, is a predacious mite feeding on Thrips tabaci Lind. It appears to be one of the few natural enemies of this insect.

There are five stages in the life cycle of the mite; these are: egg, larva, protonymph, deutonymph and adult.

The mites first appear in June and are found on the plants until December, by which time the thrips have disappeared for the season.