bluuebunny/crossref_metadata_2025_split huggingface dataset:
OBSERVATIONS ON THE ENSHEATHED LARVAE OF SOME PARASITIC NEMATODES.
Authors: GOODEY T. 
Published: February 2008

SUMMARY.

The eggs of Graphidium strigaswm and Trichostrongylus retortae‐formis give rise, under suitable cultural conditions, to larvae which finally become ensheathed and wander from the culture medium.
A new and easily manipulated method of experimentation for skin infection work is described, in which skin from a young freshly killed animal, rat or mouse, is stretched over a hole in a piece of sheet‐cork and pinned in position. The cork is floated on N saline at 37oC. and care is taken to ensure that the saline comes into contact with the underside of the skin. A drop containing the larvae to be tested is placed on the upper surface of the skin. The saline is contained within a suitable glass jar and the whole can be placed on the stage of a binocular dissecting microscope and the surface of the skin examined at any moment.
By this method it was found that ensheathed larvae of Necator americanus leave their sheaths and penetrate the skin when the drop of water containing them is allowed to evaporate and become sufficiently shallow to enable them to obtain a purchase against the surface of the drop. These larvae are very actively motile at 37oC.
Ensheathed larvae of G. slrigosum and T. retortaeformis do not penetrate the skin under exactly the same experimental conditions. They are not actively motile at 37oC. but become coiled and quiescent at this temperature. Their temperature for optimum* activity is shown to be between 22oand 25oC.
Ensheathed larvae of N. americanus cannot resist desiccation in air at room temperature and cannot revive on being moistened, whereas the larvae of G. strigosum and T. retortaeformis can withstand air desiccation and are easily revived on being remoistened. It is shown that the ensheathed larvae of these two species are more resistant to plasmolysing agents than the ensheathed larvae of N. americanus.
The sheath surrounding the larvae in all three species named in the foregoing paragraph is composed of a very resistant substance whose composition is not known. It is not true chitin since it is readily soluble in 5 per cent, caustic soda.
LEAF CHARACTER IN REVERTED BLACK CURRANTS
Authors: Lees A. H. 
Published: February 2008

ABSTRACT.

A means is indicated whereby reverted leaves may be identified even in very slight cases or where the leaves have almost regained normality.This method depends (a) on counting the number of submain veins running from the midrib to points in the margin, and (b) on observation of the margin points, which also may if necessary be reduced to t numerical basis.
That reverted leaves may be produced by artificial means, but that this reversion is of a temporary character. In each case examined the plant appeared to be under a special stimulus to growth.
Cases in the field were examined in detail in three respects, namely (a) leaf vein number, (6) mite infected buds, and (c) leaf margin. Three classes could be distinguished: (o) normal healthy, (b) simple reverted, and (c) mite infected (reverted). These corresponded with three facton which appeared to be acting: (a) seasonal factor, (b) reversion factor, and (c) mite factor. Furthermore, since “oak leaf” is an advanced stag of reverted leaf and is always associated with mite, the chances an that reverted leaves when found without “oak leaf” owe their existence in some way or other to the mite factor either patently or latently.
“SLEEPY DISEASE” OF THE TOMATO1
Authors: BEWLEY W. F. 
Published: February 2008

SUMMARY.

1. “Sleepy Disease” or “Wilt” of tomatoes may Joe caused by one of two fungi, Fusarium lycopersici or Verticittium albo‐atrum.
Massee's “diplocladium stage” of F. lycopersici has been shown to be V. albo‐atrum.
The wilt producing fungi attack the roots and grow up through the vascular bundles into the stem, leaves and sometimes the fruits. The wood of a diseased plant is a light or dark brown colour.
The average temperature is a “limiting factor” in determining which fungus is active. F. lycoperstci grows best at an average temperature of 27‐8‐28‐9oC. If the temperature remains constantly much below this, little infection results. V. albo‐atrum develops well at temperatures from 15‐6‐24‐0oC, being most active at 2M‐22‐8oC. Above an average temperature of 25oC. little infection occurs.
The average temperature conditions existing in glasshouses in this country are generally too low for F. lycopersici and consequently it is rarely found as a cause of tomato wilt. The relatively low temperatures are favourable to V. albo‐atrum, which accordingly is the most important cause of wilt.
Wilted plants soon die under conditions of low temperature, but if the average temperature be raised above 25oC, they recover and will bear a crop so long as the high temperature is maintained. When the temperature again drops, wilt reappears and death results.
V. albo‐atrum from tomato readily induces wilt in the potato, eggplant, snapdragon, cotton, pepper plant and cucumber, and produces a stunted condition of the sycamore and elm.
A number of different strains of V. albo‐atrum have been isolated which vary in their rate of growth, the amount and rate of production of microsclerotia, and in colour production; but no evidence has been obtained^to show that there may be different strains restricted to different varieties of tomatoes.
In pure culture the fungus has been shown to produce a large number of enzymes and there are strong indications that substances of a toxic nature play an important part in producing wilt.
There is a distinct relation between hardness of growth and susceptibility to wilt; the harder growing varieties and plants suffering from starvation or a severe check in the young stages being most susceptible to attack. Most varieties of tomatoes cultivated in this country are susceptible to Vertidllium, but Manx Marvel has proved to be practically immune and Bides' Recruit highly resistant.
Certain cultural devices, including regulation of the temperature and shade, have been devised which assist “wilted plants” to recover.
Further investigations upon soil sterilisation and the production of resistant varieties are in progress.
BIOLOGICAL STUDIES OF APHIS RUM WIS LINN. REPRODUCTION ON VARIETIES OF VICIA FABA.
Authors: DAVIDSON J. , FISHER R. A. 
Published: February 2008

SUMMARY.The reproduction of Aphis rumicis was tested on 18 varieties of field beans and the results compared with the reproduction on Prolific Longpod broad beans.The aphids used in the experiments were the offspring from one Fundatrix.The experiments were all carried out under similar conditions. Five plants of each variety were tested, and the total number of aphids produced on each plant, from one a. v. ♀, in 14 days was counted.The mean values of infestation for the varieties range from 37 to 1037, vide Tables I and II.These mean values allow of the varieties being grouped into classes representing various grades of susceptibility, ranging from 98 per cent. to 3 per cent, vide Table III. Vicia narbonensis has a very low susceptibility. The results obtained indicate that resistance or susceptibility may be largely determined by genetic factors in the plant.
STUDIES IN BACTEEIOSIS. VIII
Authors: PAINE SYDNEY G. , BEWLEY W. F. 
Published: February 2008

Summary.The organism which produces “Stripe” disease of the tomato is shown to be the cause of a number of “Streak” diseases of other plants, namely sweet pea, culinary pea, broad bean, french bean, red clover, lucerne, lupin, vetch, sainfoin and potato.
THE HEALING OF WOUNDS IN POTATO TUBERS AND THEIR PROPAGATION BY CUT SETS
Authors: PRIESTLEY J. H. , WOFFENDEN LETTICE M. 
Published: February 2008

Summary.

The sequence of events during the healing of the cut surface of a potato tubei is carefully traced.Apart from unessential colour changes, the first process in the healing of the tuber is the deposit of a fatty “suberin” layer, formed by the oxidation and condensation of fatty substances depositing from the sap drying up in the tissues at the cut surface.
The condition essential to the formation of this layer is access of oxygen.
If the cut surface is exposed in a moist atmosphere the layer is continuous; in a dry atmosphere, especially in sunlight, the layer may not be continuous.
This layer forms within 24 to 48 hours. A few days later cork is formed below this suberin deposit as the result of cell divisions in an actively dividing layer, the cork phellogen.
The essential factors promoting the activity of this phellogen appear to be the accumulation behind the blocked surface of sap containing substances diffusing from the vascular bundles, and the production of an acid reaction just below the blocked surface by the anaerobic conversion of sugars into fatty acids.
The activity of the cork phellogen may be roughly estimated by the numbeT of layers of cork produced. Comparative data are presented for a number of varieties of potato which show that Majestic, King Edward VII and Bishop are particularly deficient in this important activity connected with the healing of wounds.
The bearing of these facts as to the process of wound healing is considered in relation to the practice of propagation by potato sets and two practical conclusions drawn. (1) Potato tubers should not be cut in sunlight or left in too dry a place. (2) The practice of liming potato sets appears to be without justification so far as its use in promoting the healing of the wound is concerned.
STUDIES IN BACTERIOSIS. IX
Authors: PAINE SYDNEY G. , LACEY MARGARET S. 
Published: February 2008

Summary.The “streak” disease of beans (Chocolate Spot Disease) is caused by B. lathyri.Moist and warm conditions are responsible for the appearance of the disease in epidemic form.The disease is spread by wind, black fly, and the bean beetle.Methods of control are suggested.
EFFECT OF WEIGHT OF SEED UPON THE RESULTING CROP
Authors: BRENCHLEY WINIFRED E. 
Published: February 2008

Summary.

Field experiments, especially in America, nave indicated that, with annual plants at least, better crops are usually obtained by the use of heavy seed in preference to light, whether equal numbers of bushels or equal numbers of seeds are sown per acre.
Water culture experiments with peas and barley have shown that there is a steady and considerable rise in the dry weight of the plants as the initial weight of the seed increases. This occurs both with a limited and abundant food supply.
The efficiency index (rate per cent, increase per day) falls gradually as the weight of the seed rises. With prolonged periods of growth this tends ultimately to counterbalance the initial advantage gained by plants from the heavier seeds, but with annual crops as cereals, peas, etc. harvesting occurs before this equilibrium is reached, leaving the advantage with the heavier seeds.
The relative development of shoot and root is to some extent influenced by the initial weight of the seed, but may vary with the species and with the amount of available food.
The results lend support to the growing agricultural practice of advocating the use of large heavy seed, especially with annual crops. The advantage in the case of perennials would appear to be less, if any, but this has not been determined by laboratory experiments.
THE KILLING OF BOTRYTIS CINE RE A BY HEAT, WITH A NOTE ON THE DETERMINATION OF TEMPERATURE COEFFICIENTS
Authors: SMITH J. HENDERSON 
Published: February 2008

Summary.The spores of Botrytis cinerea were exposed to the action of hot water at temperatures ranging from 31oC. to 50‐3oC, the proportion of spores surviving at different times determined, and the results plotted for each temperature. These give a series of approximately symmetrical sigmoid curves, all exactly alike one another except for the change in the speed of killing at different temperatures. The curves are superimposable on adjustment of the time scale, and in this respect they differ from the curves obtained with phenol, where the shape changes from an S to a J shape as the strength of phenol is increased, eventually becoming logarithmic.The shape of the general curve agrees excellently with a recognised type of frequency distribution, and the observations at all the temperatures examined fall closely on the curve of this distribution.The effect of temperature on the velocity of the reaction is unusually great, and is well expressed by the formula of Arrhenius, if the temperature is reckoned from 0oC. instead of the absolute temperature.By combination of the formula for the curve and the formula for the velocity‐temperature relationship it is possible to express completely for the spores of Botrytis the whole of the killing process for any temperature within the Mmits studied under the conditions and with the strain used in these experiments.It is pointed out that in the estimation of temperature coefficients comparison of the times taken to reach a constant result give more accurate and consistent values than comparison of the results reached in constant time.
APPLES ATTACKED BY THE LARVAE OF THE DOCK SAWFLY (AMETASTEGIA (TAXONUS) GLABRATA, FALLEN)
Authors: PETHERBIDGE P. E. 
Published: February 2008

Summary.The larva of the dock sawfly, Ametastegia glabrata, Fallén, which is a leaf feeder usually found on docks and polygonums, injured apples in East Norfolk by boring small holes into the flesh in which to pupate. They made from one to six holes in each fruit. They were kept in check by keeping the orchard clean.
FURTHER OBSERVATIONS ON THE PREVALENCE AND HABITS OF OSCINELLA FRIT, LINN.
Authors: CUNLIFFE NORMAN 
Published: February 2008

Summary.

Observations on the prevalence of the imago of Oscinella frit in the field have been made during the period 1919 to 1922.
The annual cycle consists of three generations: Generation III swarms from the end of April to the middle of June, with a maximum about May 26; Generation I from the end of May to the middle of August, with a maximum about July 15; Generation II from the end of July to the beginning of September (or longer) with a maximum about August 19.
Although meteorological variations during the period 1919 to 1922 were apparently very diverse, they were not sufficiently diverse to affect the prevalence periods of the fly on the crop materially; the prevalence curves of the different years show a remarkable similarity. This may be due to the fact that the larva is an internal feeder.
As the periods of maximum prevalence are not displaced from year to year, it would appear that the fly population is determined by the total number of host plants and not by the cultivated plants alone.
The larva exhibits a strong tendency to attack those regions of the plant which are in receipt of abundant supplies of sap.
NOTE ON THE ECONOMIC VALUE OF THE NEUROPTERA, WITH SPECIAL REFERENCE TO THE CONIOPTERYGIDAE
Authors: WITHYCOMBE C. L. 
Published: February 2008

Summary.

The Neuroptera as a whole are distinctly beneficial to man. Three families of economic importance are represented in Britain; the Coniopterygidae, Hemerobiidae, and Chrysopidae.
The Coniopterygidae are far more common in England than is generally supposed. In general facies they resemble Aleurodidae, but can easily be distinguished.
The eggs are laid generally at the edges of leaves. Larvae are top‐shaped, with small head and mouthparts. They are predacious. After two moults a flat, circular cocoon is spun.
Larvae of Conwentzia are very beneficial on oaks in England, where they prey upon small Rhynchota, such as Phylloxera, and mites.
They would seem to lend themselves particularly well to employment economically and might be introduced to peach houses in England.
Six imagines of Conwentzia released upon a pear tree infected with Bryobia praetiosa K., resulted in roughly one thousand individual cocoons at the end of the season 1921.
Conwentzia could probably be introduced successfully into other countries where the genus does not exist. Parasites must be rigidly guarded against.
The Hemerobiidae are more often found in woods than elsewhere in Britain. Some shew preference to conifers, others to deciduous trees. Boriomyia subnebulosa Steph. is common in orchards and gardens near London.
The larvae of Chrysopidae differ from Hemerobiidae by possessing throughout life a trumpet‐shaped empodium, and generally setigerous tubercles.
As in Hemerobiidae, larvae, according to species, shew preferences to different trees.
Chrysopa prasina Burm. is a valuable check upon Chermes, on conifers; C. tenella Schn., and C. septempunctata Wesm., on Eriosoma lanigerum Hausm., of apple; while C. phyllochroma Wesm., probably does valuable work in bean‐fields in some parts.
THE DENSITY OF UNICELLULAR ORGANISMS
Authors: ALLISON R. V. 
Published: February 2008

SUMMARY.

By measuring the rate of fall of certain unicellular organisms of known diameter under appropriate conditions, their density has been calculated by the formula of Stokes.
According to this method the average ansity of algal cells studied is 1.098 and that for the cysts of Gonostomum sp. 1.057.
The density of the algal cells was found to vary greatly between the larger and smaller sizes, while that for cells intermediate was fairly constant. In the case of protozoan cysts the total variations in average density was much less marked.
It was found that during maturation, the cysts of a certain species of Colpoda decreased to one fourth their original volume, while their average density increased from 1.04 to 1.06.
Since many of the 4‐day cysts of Colpoda sp. excysted during or shortly after the measurement of their density, the average density, 1.042, for this group is thought to represent quite accurately the density of the young animals in this early stage.
By the application of the formula of Hehner and Richmond to the density values so obtained, a tentative value has been derived for the actual dry matter of the cells studied.
It has been found by calculation upon this basis that the dry matter of the young cysts (4‐day) of Colpoda sp. amounts to 10.6 per cent. while at the later stage (20‐day) it is 15.1 per cent.
It appears that 64.3 per cent, of the total dry matter of the cyst and 76.2 per cent, of the water content are lost during maturation. With regard to the total percentage of loss in terms of either constituent, it has been found that water represents 90.9 per cent, and dry matter 9.1 per cent, of the total loss respectively.
THE MULBERRY “BLIGHT” IN BRITAIN
Authors: WORMALD. H. 
Published: February 2008

SUMMARY.

The occurrence of bacterial Mulberry “Blight” in Sussex and Kent is here recorded.
It has been found on well‐established trees, on “stools,” and on young trees during the first and second years after removal from the stools.
The bacterium causing the disease has been isolated from lesions on the leaves and this has been found to conform to descriptions of Bacterium mori Boyer and Lambert.
THE ACTION OF SOME ORGANIC COMPOUNDS UPON THE CUCUMBER‐HOUSE WOODLOUSE
Authors: SPEYEE E. R. , OWEN OWEN 
Published: February 2008

SUMMARY.With a view to the winter control of the cucumber woodlouse the action of a number of compounds has been tested. Observations are described on the effects due to contact, vapour and mixing with the soil.The organism of the animal is not affected in a similar manner by different compounds. p‐Cresol and p‐Nitrophenol are less active than the corresponding ortho‐compounds and both nitro‐phenols are less active than phenol.Certain compounds show a maximum activity shortly before their disappearance from the soil. Phenol and the cresols were the most active compounds tested. Naphthalene ceases to act in the soil on the fourth day after mixing.
A ROOT DISEASE OF THE TOMATO CAUSED BY COLLETOTRICHUM TABIFICUM (HALLIER PRO PASTE) PETHYBRIDGE
Authors: BEWLEY W. F. , SHEARN J. 
Published: February 2008

SUMMARY.

A root disease of the tomato, due to Colletotrichum tabificum (Hallier pro parte) Pethybridge, has been investigated and described.
The pathogen is considered to be identical with Rhizoctonia tabifica Hallier, Vermicularia varians Ducomet, Sclerotium setosum Bewley and Shearn, and possibly Colletotrichum solanicolum O'Gara.
INVESTIGATION OF THE STRUCTURE OF REVERTED BLACK CURRANTS
Authors: RIDLER WINIFRED F. F. 
Published: February 2008

GENERAL CONCLUSIONS AND SUMMARY.No actual qualitative differences in structure have been observed between normal and reverted plants of Ribes nigrum; those that have been observed being rather quantitative, i.e. differences in degree only, e.g. amount of gum present, and variations in the amount of wood and medullary ray tissue.Briefly the main differences showing to a greater or lesser extent practically all through the plant are a reduction in the amount of wood, and a consequent increase of medullary ray tissue, coupled with a tendency to produce more gum in the revert plant than in the normal.On the whole, it is very difficult to correlate the morphological evidences of the disease with any of the anatomical differences observed, as the latter seem quite inadequate to account for the comparatively large morphological effect.The general reduction in the amount of wood present, does not seem sufficient to account for the generally smaller and more unhealthy appearance of the revert bush; nor in the petiole even combined with a certain amount of blocking by gum, can it be held to account entirely for the typical reverted leaf. with fewer veins and reduced leaf surface. In the case of the fruit, although the vascular system is reduced, there seems no reason why some of the ovules at, least should not develop. It is probable that there is some physiological factor at work causing hypertrophy and abortion.My thanks are. due t o Mr A. H. Lees, who has supplied me with all material and given much valuable help and advice. I also thank 31r F. Summers and Professor O.V. Darbishire for their advice and interest in the work.
SOME OBSERVATIONS ON THE GROWTH OF RHIZOCTONIA CROCORUM (PERS.) DC. IN PURE CULTURE
Authors: BUDDIN W. , WAKEFIELD E. M. 
Published: February 2008

SUMMARY.The organism dealt with in this paper is that which has been commonly known in this country as Rhizoctonia violacea Tul. but until satisfactory proof is forthcoming of a spore stage of the organism it should be known by its valid prior name, Rhizoctonia Crocorum (Pers.) DC.The methods used for isolation of the fungus in pure culture are described and some account given of preliminary inoculation experiments with the re‐isolation of the parasite.It is shown that growth of R. Crocorum will occur on a very wide range of sterilised artificial material when in pure culture.No spore form has occurred in any of the large number of cultures which have been grown.Some notes are given on difficulties arising in temperature relation work from differences in the “internal condition” of the organism under varying conditions, and it is shown that the optimum temperature for the growth of the organism in culture on meat‐malt extract agar as measured by the increase in diameter of colonies is in the neighbourhood of 25.5° C. This optimum temperature probably explains the geographical distribution of the severe attacks of the organism in the field.
OBSERVATIONS ON THE LIFE HISTORY OF TAPEWORMS OF THE GENUS MONIEZIA
Authors: JENKINS J. R. W. 
Published: February 2008

SUMMARY.The period during which lambs may become infected with Moniezia spp. is not confined to the Spring, but may extend at least until August.Sheep as well as lambs may become infected.Neither the distribution of the genus nor the fauna of infected farms has been of guidance in discovering the life history.Examination of the intestinal contents of lambs which had become heavily infected shortly before death gave negative results.Attempts to produce infection of possible intermediate hosts by feeding with mature proglottides gave negative results.Five species of Moniezia have been collected at Aberystwyth, and there is every reason to suspect the occurrence of further species.