bluuebunny/crossref_metadata_2025_split huggingface dataset:
ZONE LINES IN PLANT TISSUES
Authors: CAMPBELL A. H. , JUnNSQN; R E. 
Published: February 2008

SUMMARYThe black lines of Polyporus squamosus have been found in the wood of elms. Isolations were made from these lines and an account of the development of P. squamosus in artificial culture is given. Particular mention is made of the formation of black plates, or lines as they appear in section, in culture media and of the appearance of abnormal fructifications. Pure cultures of the fungus on sterilized wood blocks have produced black lines in the wood, similar to those occurring in nature.From a consideration of the structure and formation of the black plates, the suggestion is made that they form the limiting layer or rind of sclerotium‐like bodies buried in the attacked wood.A review is given of sclerotium formation and structure in several species of Polyporus, and analogies are made between these sclerotia and the sclerotium‐like body of P. squamosus. It is decided to distinguish the P. squamosus body from these sclerotia by naming it a pseudo‐sclerotium, on the criteria previously advanced for Armillaria mellea(8).
THE VIRUSES CAUSING TOP NECROSIS (ACRONECROSIS) OF THE POTATO
Authors: BAWDEN F. C. 
Published: February 2008

SUMMARYIt is shown that top necrosis can be produced in different potato varieties by a number of viruses. The reactions of these viruses on a large number of commercial varieties are given, together with certain of their properties and methods by which they can be transmitted. By grafting and needle inoculating infected potatoes to the four varieties Epicure, Arran Victory, President and Up‐to‐Date, and noting the type of necrotic disease produced on these differential hosts, it has been found possible to distinguish with a fair degree of accuracy between six viruses. The necrotic reactions of these varieties are given below.The writer has great pleasure in expressing his gratitude to Dr D. R,. Salaman for permission to make use of the virus material, and for many valuable suggestions.
THE ROLE OF PLASMODESMS IN THE TRANSLOCATION OF VIRUS
Authors: SHEFFIELD F. M. L. 
Published: February 2008

SUMMARYAlthough intracellular inclusion bodies may occur in every cell over large areas of the epidermis, they have not been found in the guard cells of the stomata. No protoplasmic connexions could be shown to exist between the guard cells and the surrounding tissues. These findings suggest that, owing to the absence of plasmodesms, the virus is unable to reach the guard cells. Support is lent to the view that, when the virus moves in the ground tissue of the host, it is carried from cell to cell along the protoplasmic bridges.
THE CHARACTERS OF SOME COLIFORM BACTERIA ISOLATED FROM GRASS AND GRASS SILAGE
Authors: ALLEN L. A. , HARRISON J. 
Published: February 2008

SUMMARYThe species of coliform bacterium predominant on fresh grass was found to be a capsulated type growing well at 30o C. but unable to grow at 37o C. For this reason it will not be detected by the presumptive test in bile salt‐lactose broth at 37o C. The name Bacillus (Aerebacter) aerogenes graminis is proposed for this species.It is possible that conforms of the above type contribute to a small extent to the initial fermentation of the silage. Those coliforms giving the presumptive test at 37o C. were found in such small numbers in the silage investigated that their influence was concluded to be negligible.This work forms part of some research carried out under grant from the Research Council of Imperial Chemical Industries, Ltd., to whom the authors wish to make due acknowledgement. Valuable help was also received from Dr S. J. Watson, who supplied samples of grass and silage‐
FURTHER EXPERIMENTS ON THE CONTROL OF THE HOP RED SPIDER MITE, TETRANYCHUS TELARIUS L
Authors: JARY S. G. 
Published: February 2008

SUMMARY

Small‐scale experiments with a number of spray fluids gave the following results against Tetranychus telarius on hops:

Lime sulphur at a concentration of 1/80 proved very toxic to the mites, but a second application had to be made to deal with those which hatched subsequently from eggs.
Emulsions of a “water white” petroleum oil at 2 and 1 per cent. Concentrations were very toxic to the mites but caused marked oedems.
Whale oil‐potash soap at 1 and ½ per cent. Concentration; cotton‐seed oil emulsion, 6 pints of il per 100 gallons of wash Derris extracts of 0.005 per cent. Rotenone and0.002 per cent. Rotenone content, and pyrethrum extract of 0.0025 per cent. Content of pyrethrins 1 and 2 were all without appreciable toxic effect upon the mites.

Lime sulphur at 1/80, to which a wetter of the sulphonated lorol type was added proved successful in the field for the control of T. telarius on hops. No injury to the plants resulted from the use of Bordesux mixture on the same plants.
SOIL CONDITIONS AND THE TAKE‐ALL DISEASE OF WHEAT
Authors: GARRETT S. D. 
Published: February 2008

SUMMARY 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

SUMMARYA. 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

SUMMARYFour 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

SUMMARYAs 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

SUMMARY

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

SUMMARY

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

SUMMARYA 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

SUMMARY

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

SUMMARYAn 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

SUMMARY

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

SUMMARY

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

SUMMARYFrom 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.