bluuebunny/crossref_metadata_2025 huggingface dataset:
ESQUISSE ÉCOLOGIQUE DES COMTÉS DE L'ISLET ET DE KAMOURASKA
Authors: Hamel Par Aubert
Published: August 2008

The vegetation of the region south of the St. Lawrence estuary, more specifically L'Islet and Kamouraska counties, is described in relation to soils and physiographic features.In the first part, a climatic, geologic, geomorphic, and phytogeographic approach is made, summarizing known data for the region. The second part is devoted to the natural vegetation, particularly in its primeval state.On the estuarian lowlands, in the southwest part, the dominant feature is a sugar maple forest which maintains itself in good condition along the coast as far as Saint-Roch-des-Aulnaies. Farther to the northeast, maples are restricted to the Champlain terraces, along the appalachian foothills. The perpetuation of the maple woods is relatively precarious on account of the cold climate. In many cases, maple woods seem to be a relic vegetation. White spruce often reclaims hills where maples have been cut down, especially when the parent-material of the soil has a low calcium content. In the northeast, spruce is the dominant feature of the landscape, on account of the siliceous rocks and a slightly colder climate.On the seashore, the sandy beach facies is characterized by a lyme-grass fringe, and the alluvial mud-flat facies is characterized by salt-water cord-grass. The latter constitutes the original phase of the silty clay soils of the lower plain. In the fresh-water section of the estuary, the alluvial muds, under tidal influence, are characterized by American bulrush and wild rice.Because of its fertile soils, the upper clay plain of the lowlands is entirely under an agricultural régime. Some reliquary fragments of forest allow us to reconstruct the primeval vegetation. In the southwest, a stand, of red maple, associated with American elm, possibly covered these flat and poorly drained soils. In the northeast, there might have been a spruce–sphagnum type of vegetation.The upper Appalachian Plateau has a rolling topography. A maple forest grows on the glacial till of the hills, where limestone delays podsolization. More often a mixed wood occurs, with white spruce, red maple, balsam fir, aspen, and white birch. The depressions are characterized by a black spruce forest, often associated with American larch and eastern white cedar. It seems that red pine and white pine have been characteristic elements of fluvioglacial soils. A coniferous forest is dominant on all sites in the northeastern part of the Plateau.
FLOWER DEVELOPMENT IN THE LOWBUSH BLUEBERRY
Authors: Bell Hugh P. , Burchill Jane
Published: August 2008

In the lowbush blueberry, floret primordia appear during June. Floral parts appear in acropetal succession during July. Ontogenetically the carpels are at first appendicular and later receptacular. The epigynous floret, in miniature, is formed by the first of August. During this month, some reproductive tissue is differentiated in both ovary and stamens. The characteristic resting stage is assumed during the autumn. Mitosis was observed in material collected during January and by late winter a number of ovules had two adjacent archesporial cells, the outer one later becoming functional. Definite differentiation starts during March. Active growth, including the initiation of meiosis, becomes general during April. Meiosis is completed in the anthers during the first week of May and about a week later in the ovules. Subsequent development in the ovule is of the Polygonum type. The flower is mature by the last week in May.
STUDIES ON RUBUS VIRUS DISEASES IN BRITISH COLUMBIA: I. RUBUS YELLOW-NET
Authors: Stace-Smith R.
Published: August 2008

A virus disease occurring on Himalaya blackberry (Rubus procerus P. J. Muell.) was transmitted to Washington red raspberry (R. strigosus Michx.), tropical black raspberry (R. albescens Roxb.), and North American black raspberry (R. occidentalis L.). A net-like chlorosis of the tissue bordering the smaller leaf veins is the characteristic symptom, consequently the name "Rubus yellow-net" is proposed for the virus and disease. The virus is transmitted by the raspberry aphid Amphorophora rubi Kalt. It may be acquired by the aphid after a one-hour feeding and usually persists in the vector less than four hours.
ABSORPTION AND UTILIZATION OF C14-GLUCOSE BY DETACHED WHEAT LEAVES
Authors: Vittorio P. V. , Krotkov G. , Reed G. B.
Published: August 2008

Thirteen-day-old wheat plants were placed on solutions of C14 labelled glucose and the amounts of glucose taken in were determined. Plants were then placed in darkness for three hours and their CO2 production was measured. It was found that the amount of glucose absorbed by plants was directly proportional to the amount of water taken in while the presence of inorganic phosphate depressed absorption. Glucose was absorbed in larger amounts than glucose-1-phosphate and the absence of oxygen had no effect on the amounts taken in. An increased production of CO2, following glucose absorption, came both from the glucose taken in as well as from the endogenous substrate.
A FLOTATION METHOD FOR OBTAINING SPORES OF HELMINTHOSPORIUM SATIVUM FROM SOIL
Authors: Ledingham R. J. , Chinn S. H. F.
Published: August 2008

This paper describes a flotation method by means of which spores of Helminthosporium sativum may be recovered from soil. Soil mixed with a small amount of mineral oil is shaken up in water. The emulsion which collects on the surface of the water contains most of the spores originally in the soil. Approximate spore numbers are determined by microscopic examination of aliquots of the emulsion. The technique is also well adapted for obtaining spores from soil for viability studies. It may be useful in comparing the effects of cultural and chemical treatments of soils on spore populations under field conditions.
STUDIES ON RUBUS VIRUS DISEASES IN BRITISH COLUMBIA: II. BLACK RASPBERRY NECROSIS
Authors: Stace-Smith R.
Published: August 2008

Raspberry indexing in British Columbia demonstrated that several varieties are carrying a latent virus that induces mild symptons in other red raspberry varieties and severe symptoms on black raspberries (Rubus occidentalis L.). The name black raspberry necrosis is proposed for the disease and virus. The virus is transmitted by the aphid Amphorophora rubi Kalt. It may be acquired by the aphid after a half-hour feeding and transmitted with a two-minute transfer feeding. Most aphids lose their ability to transmit the virus within one and a half hours after leaving the source of inoculum.
MICROFUNGI: II. THYROSTROMELLA HÖHN. AND THYROSTROMELLA SYD.
Authors: Hughes S. J.
Published: August 2008

Thyrostromella Höhnel (1919) is based on Sporidesmium myrianum Desm.; this is illustrated and redescribed. Thyrostromella Sydow (1924) is a later homonym; it is based on Coryneum trimerum Sacc. which, with four other congeneric North American species, is illustrated and redescribed in Coryneum.
DOWNY MILDEW OF DACTYLIS GLOMERATA CAUSED BY SCLEROPHTHORA CRYOPHILA
Authors: Jones Walter
Published: August 2008

A disease of orchard grass (Dactylis glomerata L.) caused by a downy mildew, Sclerophthora cryophila n. sp., was first found in Saanichton, near Victoria, B.C., in 1948. The symptoms appear on the leaves as light brown, oval-elongate to irregular areas, and as interveinal and marginal streaks. The inflorescences are occasionally affected. Zoospores are liberated from sporangia at 1 °C., but the most favorable temperature for their emergence is between 4° and 9 °C. The disease is considered of economic importance, particularly where orchard grass is grown for seed. Control involves the use of seed from disease-free crops and the application of fungicidal sprays or dusts during late autumn and late winter.
ARCTIC AEROPALYNOLOGY: SPORA OBSERVED ON STICKY SLIDES EXPOSED IN VARIOUS REGIONS IN 1950
Authors: Polunin Nicholas
Published: August 2008

Sticky slides were exposed more or less throughout the summer of 1950 in widely scattered arctic and other northern areas including Point Barrow, Alaska, northern-central Baffin Island, Jan Mayen Island, and Spitsbergen. Although the spora were generally sparse and conclusions must be regarded as tentative, it appeared that near ground level the incidence of pollen grains tended in general to coincide with the main period of flowering but that moss spores were in the air more or less throughout the growing season. Most (but by no means all) of the pollen observed could have been of local origin except in Spitsbergen, where there tended to be a preponderance of abietineous winged grains (mostly of Pinus) which were persistently caught practically throughout the brief summer although they had evidently been blown in from at least several hundred miles away.
COMPARATIVE STUDIES OF NORTH AMERICAN AND EUROPEAN CULTURES OF THE ROOT ROT FUNGUS, FOMES ANNOSUS (FR.) COOKE
Authors: Etheridge D. E.
Published: August 2008

Cultures of Fames annosus originating in Europe could not be distinguished from those originating in North America either by colony appearance, growth rate, pH optimum, or cellulolytic activity. Three growth rate types on 2.5% malt agar were recognized and these are ascribed to individual variation rather than to host or geographical influences. Successive subculturing produced variants that fell into three growth classes. Half of the isolates displayed spontaneous, but reversible, changes in growth rate and colony appearance during subculturing and this is discussed from the standpoint of genetical and environmental influences. Cultures displaying different morphological characteristics and linear-growth rates differed little metabolically; each had a similar pH optimum ranging from 4.6 to 5.5, and each proved capable of altering the initial acidity of the medium to a reaction which was more suitable for growth. Two cultures were characterized by double pH optima at 4.6 and 5.5. Cultures having different linear-growth rates produced about the same dry-weight of mycelium on a cellulose substrate in a semisynthetic nutrient solution. On the basis of a statistical analysis of cellulose utilization by representative isolates it was impossible to distinguish between North American and European cultures.
SPECIES OF SOOTY MOLDS FROM WESTERN NORTH AMERICA
Authors: Barr Margaret E.
Published: August 2008

A study of a capnodiaceous fungus occurring on western conifers resulted in the investigation of several new or little-known species. This paper includes an emended description and developmental study of Limacinia alaskensis Sacc. and Scalia, from Alnus and various conifers. The following new species, new combination, and new variety are also described from western hosts: L. multiseptata sp. nov., Capnodium spongiosum sp. nov., L. moniliforma (Fraser) comb. nov., and L. moniliforma var. quinqueseptata van nov.
FOOT ROT OF WALLFLOWER CAUSED BY PHYTOPHTHORA MEGASPERMA
Authors: Jones Walter
Published: August 2008

A previously unreported foot rot disease of wallflower, Cheiranthus cheiri, caused by the fungus Phytophthora megasperma, was found in Saanichton, B.C., in 1953. The optimum temperature for growth of the fungus is 20° to 25 °C, the maximum approximately 31 °C, and the minimum below 5 °C. Sporangia develop at all temperatures between 5° and 20 °C, but the optimum temperature for their development is approximately 14 °C, whereas the optimum temperature for the development of organs of fusion is approximately 20 °C. The fungus proved to be pathogenic to wallflower plants only under wet soil conditions, hence it is considered that good soil drainage is an important factor in the control of the disease.
A STUDY OF VARIABILITY IN CRESTED WHEATGRASS
Authors: Knowles R. P.
Published: August 2008

Thirty-one strains of crested wheatgrass from European and North American sources were assigned to six morphological forms. These forms showed affinities to the species Agropyron cristatum (L.) Gaertn., A. desertorum (Fisch.) Roem. & Schult., A. sibiricum (Willd.) P.B., A. fragils (Roth.) Nevski, A. michnoi Roshev., and A. imbricatum (M.B.) Roem. & Schult. Typical plants, spikes, glumes, and seeds of the six forms were illustrated. Eight strains of A. cristatum were diploid (2n = 14) and two strains were tetraploid (2n = 28). Strains of all other forms were tetraploid. Chromosome counts of root tips indicated no aneuploids in 71 diploid plants and one aneuploid (2n = 29) in 96 tetraploid plants. Meiotic observations, however, indicated accessory chromosomes in 14 of 43 tetraploid plants. Diploid forms of A. cristatum crossed sparingly with tetraploid species to form sterile hybrids. All tetraploid species were interfertile and formed fertile hybrids. Most desirable strains agronomically were of the species A. cristatum, A. desertorum, and A. imbricatum. Most vigorous hybrids were sterile plants from crosses of A. desertorum and A. cristatum.
WINTER RESTING STAGES OF CERTAIN ERICACEAE
Authors: Bell Hugh P. , Burchill Jane
Published: August 2008

The winter resting stages of 17 species of Ericaceae are described, figured, and analyzed. From this analysis, the following deductions were made: (1) Each species has a fairly definite winter resting stage. (2) As rates of development vary from species to species, the winter resting stage is not in all cases related to the time of full bloom. (3) The embryo sac and anther do not develop at similar rates; hence, for any stage in the development of one, there is not a definite accompanying stage in the development of the other. (4) The Ericaceae were not evolved in a climate which had the marked periodicity and extreme cold characteristic of our present north temperate zone.
BIOLOGY, CYTOLOGY, AND TAXONOMY OF COCHLIOBOLUS SATIVUS
Authors: Shoemaker R. A.
Published: August 2008

Cochliobolus sativus (Ito & Kurib. ex Kurib.) Drechs. ex Dast. produced mature ascocarps on seeds of Zea mays L., previously disinfested with mercuric chloride, boiled one minute to kill the embryo and partly immersed in Sach's agar. Isolates of the conidial state, Helminthosporium sorokinianum Sacc. ex Sorokin (= H. sativum Pamm., King & Bakke), and monoascosporic isolates were hermaphroditic and heterothallic. Uninucleate, spherical spermatia 1.7 μ wide, the sole male agents in plasmogamy, were produced in phialids in slimefilled spermogonia measuring 2.5 × 2.5 mm. Hyphal fusions and conidiation did not initiate the heterokaryon in the ascogonium. Homokaryotic isolates and incompatible crosses produced partially mature ascocarps by differentiation of maternal stroma. Pseudoparaphyses extended downwards from subapical stromatic cells and produced locules. Subsequently in compatible crosses the heterokaryotic ascogenous hyphae grew from the sub-basal pseudoparenchyma and produced a fascicle of asci in the locule. Eight scolecospores, uninucleate at inception, formed after meiosis. The asci had two walls (bitunicate) but the inner wall was not evident in asci filled with spores nor functional in spore discharge. Whole asci extruded from the ascocarp in slime and dehisced in water by a terminal circumscissile rupture. Cochliobolus Drechs. was placed in the Pseudosphaeriaceae Höhn. sensu Luttrell in the Pseudosphaeriales Thiessen & Sydow.
STUDIES IN FOREST PATHOLOGY: XV. ROOTLETS, MYCORRHIZA, AND SOIL TEMPERATURES IN RELATION TO BIRCH DIEBACK
Authors: Redmond D. R.
Published: August 2008

Cylindrosporium sp., isolated from dead yellow birch roots, inhibited the growth of another fungus isolated from mycorrhiza and dead roots. Growth rate of the former increased while that of the latter decreased with increased temperature above the optimum for rootlet, development. Twenty-four species of fungi were isolated from mycorrhiza. Seedlings grown aseptically in soil and in agar were inoculated with fungi isolated from dead and dying rootlets and from mycorrhiza, but none of the organisms displayed sufficient virulence to cause birch dieback. The optimum temperature for development of potted seedlings was about 18.5 °C. Increases or decreases of 2 °C. or more from the optimum for yellow birch development resulted in increased rootlet mortality, decreased frequency of mycorrhiza, and a thinner mantle of hyphae in mycorrhiza, followed by reduction in foliage vigor. Normal rootlet mortality of 6% in a 55-year-old yellow birch stand was increased to 19 and 60% by raising soil temperature 1° and 2 °C, respectively, above the normal during one summer. Soil moisture was not lowered a statistically significant amount by a 5 °C. increase until the sixth day following rain. Mycorrhiza existed on residual living roots in about the same proportion as on undisturbed root systems. The possibility that birch dieback may be the result of soil temperature increases is discussed. It is suggested that cutting practices in hardwood stands should remove all yellow birch trees or prevent increased temperatures in soil occupied by residual birch.
NUCLEAR DIFFERENCES IN ALLIUM CEPA ROOT TISSUES AS REVEALED THROUGH INDUCTION OF MITOSIS WITH INDOLEACETIC ACID
Authors: Chouinard A. L.
Published: August 2008

Treatment with the growth substance indoleacetic acid was used to stimulate mitosis in differentiated tissues of Allium cepa roots in order to establish whether nuclear differences, specifically in chromosome number, exist normally and are merely revealed by treatments, or whether these nuclear differences are produced by the treatment. With the concentrations of indoleacetic acid and durations of treatment used, evidence was obtained that: chromosome number differences exist in the differentiated tissues of onion root prior to any treatment and that the appearance of these differences after treatment is a matter of revelation and not of causation. The evidence obtained in these investigations comes indirectly from observations of nuclear size and structure and directly from rare spontaneous mitoses in untreated roots, and in the treated roots (i) from the absence of nuclear abnormalities which might explain otherwise the origin of polyploid cells, (ii) from the uniform occurrence of certain chromosome numbers in specific root tissues, (iii) from proportions of diploid and polyploid divisions during mitotic induction, and (iv) from the lack of relationship between total mitotic activity and number of polyploid mitoses. A gradient of endomitotic polyploidization exits in certain tissues along the longitudinal axis of the onion root.
ECOLOGICAL STUDY OF THE PEAT BOGS OF EASTERN NORTH AMERICA: II. THE CHAMAEDAPHNE CALYCULATA COMMUNITY IN QUEBEC AND ONTARIO
Authors: Segadas-Vianna Fernando
Published: August 2008

Data collected in this very uniform bog community lend themselves particularly well to an assessment of phytosociological criteria. Expressions of frequency, constancy, fidelity, homogeneity as proposed by various writers are tested and evaluated. At the same time, it is believed that the present paper provides an accurate description and definition of the phytosociological unit with which it is concerned.
LABORATORY STUDIES ON THE EVALUATION AND ACTIVITY OF ANTIFUNGAL FUMIGANTS
Authors: Sampson R. E. , Ludwig R. A.
Published: August 2008

A method of evaluating antifungal fumigants under substrate-free conditions by means of the standard dosage response curve is described. Results demonstrate the importance of relative humidity in ethylene oxide and chloropicrin fumigation.
SOME ASPECTS OF MONOSOMIC WHEAT BREEDING
Authors: Person Clayton
Published: August 2008

Meiotic chromosome behavior was described for a group of monosomic plants, including representatives of the F1 and the first to seventh backcross generations. All plants were partially asynaptic. Rings-of-four were commonly seen in F1. and early backcross generations. Irregularities occurring among the progenies of monosomics were also described. These included monosomic plants which, through a process termed univalent-shift, were deficient for chromosomes other than those deficient in their respective monosomic parents. It was concluded that the irregular karyotypes occur as a consequence of partial asynapsis in the parent monosomics.
STUDIES OF SOIL FUNGI. SATURNOMYCES A NEW GENUS OF THE ASPERGILLACEAE
Authors: Cain Roy F.
Published: August 2008

Saturnomyces is described as a new genus of the Aspergillaceae in which the ascospores are black but not opaque with three prominent longitudinal ridges. There is an inconspicuous imperfect stage of the Cephalosporium type having long slender phialides each with a small globoid head of viscid phialospores. A single species is described, having been isolated from peat soil collected at Thedford, Ontario.
STUDIES OF NECTAR SECRETION IN EXCISED FLOWERS: I.THE INFLUENCE OF CULTURAL CONDITIONS ON QUANTITY AND COMPOSITION OF NECTAR
Authors: Shuel R. W.
Published: August 2008

Nectar secretion was studied in excised flowers of snapdragon (Antirrhinum majus L.) grown in culture solution during the secretory period. The supply of sugar to the flower was regulated by varying the sugar concentration of the culture medium or the volume of medium entering the flower. Nectar sugar yield, as well as flower dry weight, was closely related to the sugar supply. Concentration of sugar in the nectar was almost identical with that of the medium, suggesting that osmotic work was not done by the nectaries. Sucrose consistently supported much higher yields of nectar than any of the other sugars tested, though many of the other sugars appeared to be assimilated as readily by the flower as sucrose. Sugar transformations occurred in nectar of flowers cultured on sucrose, glucose, fructose, maltose, lactose, galactose, mannose, and raffinose, but not in flowers supplied with xylose or sorbose. Sucrose spots were usually found in chromatograms of nectar in which transformations occurred. Despite the lack of evidence for the performance of osmotic work, the data are considered to support the recent suggestion by Frey-Wyssling that secretion results from metabolic activity in the nectary.
STUDIES ON THE ETIOLOGY OF A ROOT ROT OF WINTER WHEAT IN SOUTHWESTERN ONTARIO
Authors: Benedict W. G. , Mountain W. B.
Published: August 2008

The fungus Rhizoctonia solani Kühn and the root-lesion nematode Pratylenchus minyus Sher & Allen were closely and consistently associated in naturally occurring infections of winter wheat. The resultant root rot was characterized by markedly yellowed and stunted patches of plants in the wheat fields during spring growth. In greenhouse and field experiments the combined effects of the fungus and the nematode upon growth of the wheat was almost twice as great as the effect produced when either pathogen was controlled by a selective soil treatment. By pure culture techniques it was not possible to show that in the penetration of wheat roots the fungus was dependent upon the nematode or that the converse was true.
SOME ASPECTS OF THE ELONGATION OF FUSIFORM CAMBIAL CELLS IN THUJA OCCIDENTALS L.
Authors: Bannan M. W.
Published: August 2008

An outstanding feature of the elongation of fusiform initials is the high degree of variability that exists from cell to cell. This individual inconstancy is to some extent related to recurrent alterations in the local environment. Thus loss of a neighboring cell often results in accelerated elongation. Although frequently masked by the deviations in individual cells, certain general trends of growth become apparent on analysts of the data from numerous cells. In the growth cycle between successive multiplicative divisions the progress of elongation is not uniform but rather follows a familiar growth pattern, early rapid extension giving way to a gradually decreasing rate of elongation as lengthening proceeds. Growth at opposite ends of the same cell is usually dissimilar, basipetal extension tending to predominate. This bipolar difference is evident in the stems of small trees, in the periphery of the stems of mature trees, in the distal parts of branches, and to a lesser degree, in the proximal parts of recurved branches. The reduced bipolar difference in the inverted proximal portions of recurved branches indicates that gravity is not the major factor in the establishment of polarity, but does perhaps play a minor role. Cell elongation is apparently achieved by tip growth.
ECOLOGICAL STUDY OF THE PEAT BOGS OF EASTERN NORTH AMERICA: III. NOTES ON THE BEHAVIOR OF CHAMAEDAPHNE CALYCULATA
Authors: Lems Kornelius
Published: August 2008

This paper presents data and observations concerning Chamaedaphne calyculata (L.) Moench. (Ericaceae). The branching pattern, the longevity of different types of leaves, and features of flowering are shown to be correlated. The relationship between this complex of features and the habitat is studied, and a few speculations are advanced to explain the physiological basis for the behavior of Chamaedaphne. This study is essentially autecological, and it is hoped that it may constitute a link between the study of soil conditions and the response of plant hormones on the one hand, and phytosociological work in peat bogs on the other hand.
THE PRODUCTS OF STARCH HYDROLYSIS AND THEIR METABOLISM
Authors: Vittorio P. V. , Krotkov G. , Nelson C. D. , Bidwell R. G. S.
Published: August 2008

C14 labelled tobacco leaf starch digested with 1 N H2SO4 in a boiling water bath was not completely hydrolyzed to glucose even after 24 hr. After three hours' hydrolysis, paper partition, chromatography with butanol–ethanol–water solvent revealed that besides glucose there were four C14 labelled products with RF values lower than glucose. When these bands were fed individually to tobacco leaves in light they were incorporated into sucrose, glucose, fructose, and starch, and were better starch formers than glucose, glucose-1-phosphate, or maltose.
POOR FRUITERS AND BARRAGE MUTANTS IN GELASINOSPORA
Authors: Dowding E. Silver , Bakerspigel A.
Published: August 2008

Anomalous sterility and slow fruiting occur among the following types of cultures: (1) mated homokaryotic mycelia grown from dwarf ascospores; (2) heterokaryotic mycelia grown from normal-sized ascospores; (3) hyphal-tip cultures from heterokaryotic mycelia. Such behavior may be caused by a mutant nucleus whose nutritional factors do not complement those in the nuclei of opposite mating type. Among the sterile and slow-fruiting strains were found 'barrage' mutants. They differ in texture and growth rate from wild strains. When grown in pairs, their hyphac, as they approach each other, exhibit aversion or barrage. Progeny of mated barrage strains are likewise barrage strains.
CRESTED WHEATGRASS COMPLEX
Authors: Sarkar P.
Published: August 2008

In the complex of taxa commonly called crested wheatgrasses, at least five species can be distinguished according to descriptions by Nevski in the Flora of the U.S.S.R. These are: Agropyron cristatum, A. pectiniforme, A. desertorum, A. michnoi, and A. sibiricum. Of the two commercial forms of A. cristatum, 'Standard' and 'Fairway', the latter is diploid with 2n = 14. From a consideration of its chromosome number and morphological distinctness this taxon is here given specific status with the name Agropyron cristatiforme. Each of the five other species mentioned above is tetraploid with 2n = 28. Karyomorphologically all the species of Agropyron studied here are characterized by chromosomes with median or submedian centromeres and by the lack of any secondary constriction or satellite. A high frequency of multivalents in the pollen mother cells of A. michnoi and A. sibiricum indicates an autoploid derivation of these two species.
THE PHYSIOLOGY OF HOST–PARASITE RELATIONS: I. THE ACCUMULATION OF RADIOACTIVE SUBSTANCES AT INFECTIONS OF FACULTATIVE AND OBLIGATE PARASITES INCLUDING TOBACCO MOSAIC VIRUS
Authors: Shaw Michael , Samborski D. J.
Published: August 2008

Excised, parasitized leaves were placed with their bases in radioactive solutions or exposed to radioactive carbon dioxide and the uptake and distribution of the tracers followed by autoradiography. Carbon dioxide and 20 other carbon compounds, including sugars, amino and organic acids, phenols, and indoleacetic acid, and/or their metabolic products, as well as phosphate and calcium, accumulated strongly at uredial and conidial colonies of the obligate parasites Puccinia and Erysiphe, respectively. Accumulation of glucose occurred in the host tissue at the sites of mildew colonies on leaves from which the ectoparasitic fungal mycelium had been removed, paralleled the respiration, rate, increased progressively with the development of the parasites, and was most marked at type 4 infections. It was inhibited by sulphur dust (with mildew), sodium azide, 2,4-dinitrophenol and, reversibly, by anaerobiosis and was, therefore, dependent on aerobic respiration. On the other hand the tracers did not accumulate within senescent rust and mildew colonies or within the necrotic lesions produced by bacterial and fungal parasites which kill the tissues of their hosts. Radioactive glucose did not, but calcium and phosphate did, accumulate within young local lesions of tobacco mosaic virus on Nicotiana. The tracers did not enter dead areas on mechanically-wounded leaves and only accumulated at fresh wounds under conditions conducive to a high rate of water loss from the damaged surface. In conjunction with more conventional methods, tracer techniques provide a powerful method of attack on the problems of host–parasite relationships.
CANADIAN SPECIES OF SYNCHYTRIUM
Authors: Karling John S.
Published: August 2008

Twenty collections of Synchytrium from various parts of Canada were studied, and among these were S. perforatum, S. athyrii, S. rubrocinctum, S. cupulatum, and S. aureum. This is the first report of S. athyrii, S. rubrocinctum, and S. cupulatum from America. In addition to these five species, 13 short-cycled ones are described. These cannot be identified with certainty at present from the material at hand, and are not given specific names. Most of them occur on new hosts in new localities, and the collection of them greatly extends the known geographical and host range of Synchytrium.
THE PEACH REPLANT PROBLEM IN ONTARIO: III. AMYGDALIN CONTENT OF PEACH TREE TISSUES
Authors: Ward G. M. , Durkee A. B.
Published: August 2008

A chemical analysis of various tissues of the peach tree for their content of the cyanogenetic glycoside amygdalin has shown that the amount varies from none in the woody tissues to more than 50 milligrams per gram of dry tissue in some roots. The highest concentrations are found in the bark of the roots. Factors such as variety and season affect the amygdalin content.
METABOLISM OF C14 AMINO ACIDS AND AMIDES IN DETACHED LEAVES
Authors: Nelson C. D. , Krotkov G.
Published: August 2008

Detached broad bean leaves were placed with their petioles in 0.01 M ammonium nitrate and allowed to carry on photosynthesis in C14O2 for various periods from 12 to 125 min. The radioactivities of the various amino acids formed from C14O2 were determined. In addition, these amino acids were degraded by decarboxylation with ninhydrin. From the specific activity data it was concluded that the amino acid closest to the site of carbon dioxide fixation in photosynthesis was alanine, followed by aspartic and glutamic acids, with the amides farthest removed. From the intramolecular distribution of label it was concluded that asparagine and glutamine were formed from their corresponding amino acids. The labelling in aspartic and glutamic acids was not consistent with the view that these two amino acids are formed from their corresponding α-keto acids produced by operation of the conventional tricarboxylic acid cycle. A C2 plus C2 condensation is postulated for the formation of aspartic acid. A shift in the double bond in the aconitase reaction of the tricarboxylic acid cycle would account for the observed labelling in glutamic acid. When acetate-1-C14 was fed to detached broad bean leaves in the light or dark, the distribution of label in glutamic acid supported the suggestion that there is such a. shift in the double bond in the aconitase reaction. Sodium arsenite, infiltrated into tobacco leaves, inhibited the biosynthesis of asparagine but not that of glutamine.
OBSERVATIONS ON STEM CANKER AND POD AND STEM BLIGHT OF SOYBEANS IN ONTARIO
Authors: Hildebrand A. A.
Published: August 2008

Stem canker caused by Diaporthe phaseolorum (Cke. & Ell.) Sacc. var. caulivora Athow & Caldwell is a serious disease of soybeans in Ontario. Artificial inoculation experiments have indicated (a) that soybeans which are highly susceptible to infection at midstage in their development become progressively less so as they approach maturity, (b) that reduction in yield is more or less directly proportionate to earliness of infection, (c) that all varieties presently of commercial importance in Ontario are highly susceptible to the disease, and (d) that six common weeds, and tomato, pepper, and snap and field bean, are not susceptible to infection by the soybean pathogen. The tests also indicated that monoconidial isolates of the stem canker organism are as highly pathogenic as those derived from single ascospores, and that isolates, though morphologically similar, may be differentiated on the basis of their pathogenic capability. The pathogen is definitely seedborne, but infection from such a source is not of primary importance. The likelihood that the pathogen is indigenous to the soil of the soybean-growing area of Ontario is discussed. Pod and stem blight caused by Diaporthe phaseolorum (Cke. & Ell.) Sacc. var. sojae is of negligible economic importance in Ontario. The pathogen, which is observed mostly in the imperfect (Phomopsis) stage, shows little evidence of being able to infect plants until late in the growing season. In the absence of resistant varieties no better methods of control can be recommended than those of completely plowing under soybean debris, of avoiding the planting of the more susceptible varieties, and of practicing crop rotation.
THE PHYSIOLOGY OF HOST–PARASITE RELATIONS: II. THE EFFECT OF PUCCINIA GRAMINIS TRITICI ERIKS. AND HENN. ON THE RESPIRATION OF THE FIRST LEAF OF RESISTANT AND SUSCEPTIBLE SPECIES OF WHEAT
Authors: Samborski D. J. , Shaw Michael
Published: August 2008

The first leaves of resistant (var. Khapli) and susceptible (var. Little Club) species of wheat were heavily inoculated with P. graminis (Race 15B). The effect of the frequency of the pustules on their size and on the leaves is described. The oxygen consumption, total dry weight, total nitrogen, and sugar contents of leaf disks were measured at frequent intervals after inoculation. At infections of Little Club massive increases in dry weight occurred in 10 to 15 days, but the percentage total nitrogen remained close to that of healthy leaves. Oxygen consumption per unit dry weight or per unit of tissue nitrogen rose to from 2.5 to 3.0 times that for healthy tissue and then fell off again. The duration and degree of the rise were dependent on environmental conditions. At infections on Khapli, both dry weight and the percentage total nitrogen declined rapidly and the leaves turned yellow and died in about eight days, suggesting a rapid breakdown of protein. Oxygen consumption per unit dry weight or per unit of tissue nitrogen rose more rapidly, to from 2.0 to 2.5 times that of healthy tissue, and declined again sooner than at infections on Little Club. With both species, the 'accumulation' at infections of radioactive glucose, or its products, roughly paralleled the course of respiration. With leaves of Little Club, initially low in carbohydrate and having a low respiratory quotient, a marked rise in the respiratory quotient occurred at developing infections; little or no rise occurred with Khapli. The results of the sugar analyses suggested that the increase in respiration following infection was not initially dependent on an increase in the sugar content above that found in the healthy leaf. The significance of the results is discussed.
CYTOLOGICAL STUDIES OF ASCUS DEVELOPMENT IN COCHLIOBOLUS SATIVUS
Authors: Hrushovetz S. B.
Published: August 2008

Conjugate divisions occurred in the binucleate crozier of Cochliobolus sativus (Ito & Kurib. ex Kurib.) Drechs. ex Dast. Two cross walls were laid down in such a way that the penultimate cell was binucleate. A lateral bulge developed in this cell and it quickly assumed the clavate shape of the young ascus. The two nuclei in the clavate ascus fused and this was accompanied by a fusion of their nucleoli. In meiosis two divisions occurred with pairing between highly contracted chromosomes early in the first division. A third division (mitotic) followed and resulted in the formation of eight haploid nuclei. Ascospore delimitation began at this stage and each spore was initially uninucleate. Evidence of structural hybridity was seen in all divisions in the ascus. The haploid chromosome complement, as determined from pachytene and metaphase stages, consisted of seven or eight chromosomes.
STUDIES ON THE SEEDLING DISEASE OF BARLEY CAUSED BY HELMINTHOSPORIUM SATIVUM P.K. & B.
Authors: Ludwig R. A. , Clark R. V. , Julien J. B. , Robinson D. B.
Published: August 2008

A standard sand – cornmeal – nutrient salt medium, for use in the production of artificial inoculum of Helminthosporium sativum, is described. This inoculum induces uniform plant disease development when thoroughly incorporated with the planting soil. The results presented clearly demonstrate the necessity of using a series of infestation levels in studies of factors affecting disease development in artificially infested soil. It is shown that considerable reliance can be placed on treatment comparisons within an experiment but that comparisons between experiments are much less accurate. The role of a toxin (or toxins) in disease development in barley seedlings has been demonstrated. The toxic activity was found to be distinct from that frequently encountered on addition of organic matter to soil. Results obtained suggest that toxin adsorption by the soil may play an important role in reducing disease incidence and severity.
STUDIES OF COPROPHILOUS ASCOMYGETES: IV. TRIPTEROSPORA, A NEW CLEISTOCARPOUS GENUS IN A NEW FAMILY
Authors: Cain Roy F.
Published: August 2008

A new family Tripterosporaceae is introduced by the description of three species of a new genus, Tripterospora, similar in several characteristics to Podospora (Sordaria) but clearly separable by the production of globose, non-ostiolate ascocarps and of ascospores which lack gelatinous secondary appendages and sheaths. In T. longicaudata Cain sp. nov., the type of the genus, and in T. brevicaudata Cain sp. nov., early development of the ascocarp is seen to be from a coiled and twisted ascogonium as in many members of the Ascohymeniales, with the ascogonia scattered on the aerial mycelium. Ascospores in all three species are two-celled, the upper cell dark and ellipsoid with a circular germ pore at the apex, the lower cell hyaline. Descriptions and illustrations are given for the known species: T. longicaudata, isolated in pure culture from dung and from swiss chard plants in Ontario; T. brevicaudata, also observed only in pure culture, obtained from a living branch of yellow birch in Connecticut, and from tomato seed in Ontario; and the third, described by Griffiths as Pleurage erostrata, collected on dung in Ontario and Manitoba.
STUDIES IN AMERICAN ORCHIDS: II. THE GENUS BRACHIONIDIUM LINDL.
Authors: Garay Leslie A.
Published: August 2008

The genus Brachionidium is one of the most poorly defined taxa in the whole Vegetable Kingdom. The obscurity displayed in the type descriptions of B. parvifolium, B. tuberculatum, and B. concolor has prevented systematists from understanding the genus properly and from studying its position and relationship among the genera of Pleurothallidinae. The genus originally included the three above-named species. With the aid of photographs of types, recent collections have been classified. In addition to these, five new species are described, all from tropical America, viz. from the Andean Region. In addition to the complete revision of this genus, and its immediate relationship, special attention is given to all 20 genera of the subtribe Pleurothallidinae. The interrelation of these genera is examined and illustrated from a dynamic point of view.
MATERNAL INHERITANCE OF LEAF VARIEGATION IN HEXAPLOID WHEAT
Authors: Arnason T. J.
Published: August 2008

A P32-treated vulgare wheat plant produced an offspring having yellow-green stripes on the leaves. The variegated leaf character is maternally inherited. Progenies of individual variegated selfed plants differ widely in the proportions of green: variegated individuals. Green sibs of variegated plants breed true. In crosses between variegated awn-tipped and green bearded plants, the awn character segregated in a simple Mendelian fashion while the variegation appeared only in individuals whose maternal parent was variegated. Plastid mutation independent of chromosomal genes is presumed to have occurred in the P32-treated parent of the original variegated plant. On the plastid-mutation hypothesis, variegated plants have two kinds of plastids, normal and mutant, and either or both kinds may be represented in the eggs produced. When both kinds of plastids are present, segregation during embryo development may result in the variegated effect seen in the older plants.
THE OCCURRENCE OF FUSARIUM SPECIES IN CANADA: V. TAXONOMY AND GEOGRAPHIC DISTRIBUTION OF FUSARIUM SPECIES IN SOIL
Authors: Gordon W. L.
Published: August 2008

A taxonomic study was made of 1348 isolates of Fusarium found in 206 soil samples collected in 1946. Approximately 70% of the samples, or 143, were obtained from 127 localities in Manitoba; the remaining 30%, or 63, came from seven other provinces.Of 25,973 colonies of fungi that developed on the 2060 soil-dilution plates involved in this study, Fusarium accounted for approximately 5%. A total of 14 species and varieties of Fusarium, classified in nine sections of the genus, were isolated; they are F. merismoides Cda., F. poae (Pk.) Wr., F. sporotrichioides Sherb., F. avenaceum (Fr.) Sacc., F. semitectum Berk. & Rav., F. acuminatum Ell. & Ev., F. equiseti (Cda.) Sacc., F. culmorum (W. G. Sm.) Sacc., F. sambucinum Fuckel, F. sambucinum var. coeruleum Wr., F. moniliforme Sheld. emend. S. & H., F. oxysporum Schlecht. emend. S. & H., F. oxysporum var. redolens (Wr.) Gordon, F. solani (Mart.) App. & Wr. emend. S. & H. F. oxysporum, F. oxysporum var. redolens, F. equiseti, and F. solani accounted for approximately 90% of the total Fusarium isolates. F. oxysporum was by far the most prevalent species isolated. With the exception of F. merismoides, all of the species isolated were found previously to be seed-borne by cereals and to be associated with common root rot of those crops.
THE INFLUENCE OF ASSOCIATED MICROORGANISMS ON THE PATHOGENICITY OF HELMINTHOSPORIUM SATIVUM
Authors: Campbell W. P.
Published: August 2008

Six species of soil fungi were studied in association with Helminthosporium sativum. Phoma humicola, Epicoccum purpurascens, and Trichoderma viride strongly inhibited the pathogenic activities of H. sativum, while Actinomucor repens, Sclerotinia trifoliorum, and Myrothecium verrucaria were only slightly inhibitory. The pathogenicity of H. sativum was increasingly depressed by each of the six fungi as soil temperature was increased from 15° to 26 °C. The pH shifts which these fungi induced in soil were not sufficient to be considered as a factor in depressing pathogenicity. In plate tests on nonenriched soil-extract medium, S. trifoliorum and A. repens did not appreciably affect H. sativum. The other four fungi all caused distortion and breakdown of the spores, while M. verrucaria and E. purpurascens were found as internal parasites in spores of H. sativum. P. humicola, E. purpurascens, and T. viride caused the breakdown of mycelium of the pathogen, and P. humicola and E. purpurascens were found as internal parasites of the mycelium. The fungi produced substances in the medium which adversely affect the germination and growth of germ tubes of spores of H. sativum. A. repens and S. trifoliorum were least effective, T. viride and P. humicola were intermediate in their action, and E. purpurascens and M. verrucaria were very severely limiting. Two antagonistic mechanisms, antibiosis and direct parasitism, were demonstrated, both of which were responsible for disorganization of the mycelium of the pathogen. Only those fungi that caused disruption of the mycelium were able to depress the pathogenicity of H. sativum appreciably.
THE INHIBITORY ACTIVITY OF EXTRACT OF CAPSICUM FRUTESCENS ON PLANT VIRUS INFECTIONS
Authors: McKeen Colin D.
Published: August 2008

The expressed juice from Capsicum frutescens L. contains a substance that markedly decreases the formation of local and primary lesions by certain viruses on cowpea and Chenopodium hybridum L. and to a lesser extent on Nicotiana tabacum vars. Harrow Velvet and Samsun, and Physalis peruviana L. The extent to which pepper juice decreases the numbers of lesions is independent of the virus concerned and depends only on the species to which inoculations are made. Pepper juice inhibits the production of local lesions when it is applied with the virus inoculum, or to the upper and lower leaf surfaces before inoculation; but, if applied to leaf surfaces a few minutes after inoculation, pepper juice does not appreciably decrease production of lesions. Thus, it would seem that the effect of the inhibitive agent is to prevent infection by, rather than increase of, the virus. The application of the pepper extract at some distance from the point of virus inoculation also inhibits lesion formation on cowpea and Chenopodium. As judged by the reduction of lesions on cowpea, pepper extract displays about the same degree of inhibition as that of spinach, this being much greater than that of cucumber. The inhibitive component of pepper juice is thermolabile, it resists aging and drying in vitro, and does not pass through a cellophane membrane. Such characteristics indicate its protein nature. The protein component of pepper juice precipitated either by 95% ethanol or by ammonium sulphate is inhibitively active, but is less so than the raw juice.
A FURTHER STUDY ON THE GROWTH OF BRASSICA ROOTS IN SOLUTIONS OF PECTIC ENZYMES
Authors: Cormack R. G. H.
Published: August 2008

This paper describes the action of the enzyme preparation Pectinase on the epidermal cells of living roots of Brassica seedlings. The striking results obtained are attributed to the effective but non-toxic properties of the preparation and to better fungal and bacterial control.
THE CONSTITUTION OF SUGAR BEET SEEDLINGS ASSOCIATED WITH CHEMICALLY INDUCED IMPROVEMENT IN THEIR LOW TEMPERATURE RESISTANCE
Authors: Miller Sherwood R. , Corns William G.
Published: August 2008

The work concerned some chemical and physiological characteristics of sugar beet seedlings grown in darkness in vermiculite moistened with water or with 4, 8, 12 p.p.m. solutions of TCA (sodium salt of trichloroacetic acid) or of Dalapon (sodium salt of 2,2-dichloropropionic acid). The chemical treatments, which were effective in improving the cold resistance of the seedling shoots, decreased their moisture content, increased their rate of water loss, and decreased their resistance to desiccation; increased the sugar and the dry matter content; and had no appreciable effect on the amount of total nitrogen or of water soluble nitrogen in the seedlings.