Small Protuberances Research Articles

Effect of 2, 4-D sprays on the anatomical characters of some weeds

Seedlings ofAchyranthes aspera L.,Cassia tora L., andRuellia tuberosa L. were sprayed with 100, 200, 400, 600, 800 and 1,000 ppm of 2, 4-D solution. The herbicide induced proliferation of cambium in the hypocotyl and stem ofA. aspera, cambium, xylem elements and tannin cells in the hypocotyl and stem ofC. tora and cambium and phloem in the hypocotyl and stem ofR. tuberosa. It had a lethal effect on the cortex, endodermis, phloem, xylem and pith of the petiole ofC. tora, on cortex, cambium and phloem in the hypocotyl and stem ofA. aspera and on cortex, endodermis, cambium and phloem in the hypocotyl and stem ofR. tuberosa. InR. tuberosa proliferation of pericycle in the root was also seen in the form of huge masses of cells, limited in length. Endodermis and cortex from this region of proliferation had ruptured. Adventitious roots developed from the hypocotyl and internodes inR. tuberosa and only from internodes inC. tora, may be due to proliferation of phloem and cambium inR. tuberosa and of cambium inC. tora, respectively. Small protuberances on the stem region ofA. aspera were also ascribed to the proliferation of cambium. Lysigenous cavities were found in the cortex and pith of the stem ofA. aspera treated with 2, 4-D.

Near free-molecule heat transfer and density distribution between concentric spheres.

The parameter CD appears to be useful in correlating drag or impact pressure data for small protuberances immersed in a turbulent boundary layer. If h/b 60. The mean value of CD decreases from approximately 0.9 to 0.7 for 60 < hur/vw < 1300. For hUr/vw < 60, CD increases rapidly with decreasing huT/vw, and in this range the values of CD for the low-speed flow are substantially lower than for the supersonic external flows. The limited range of available data indicate a trend of increasing CD with increasing h/b.

The drag of small protuberances immersed in a turbulent boundary layer.

where p0 is the distance of the wave from the focus when measured along the first shock-shock. In the early stages of reflection, this can be roughly approximated by a circular front. The three-dimensional problem has analytical difficulties because (L/^)]A0-o cannot be easily expressed as a function of 0. However, a profile can be computed, point by point, numerically. Putting Xi, \%, . . . Xn equal to L/R for each of n reflections at a change of surface slope A0,

Growth and division of protoplasts of Bacillus megaterium and inhibition of division by penicillin.

Protoplasts of Bacillus megaterium grew well and divided in nutrient broth containing 0.5 m NaCl as the stabilizer. Protoplasts also grew when sucrose or succinate was used instead of NaCl; however, no division phenomena were observed. The sequence of growth and division was similar to the results obtained by McQuillen. Protoplasts enlarged from 1.8 to 3.5 mu in diameter, and then a small protuberance formed in the enlarged cells. The nodules enlarged until eventually symmetrical dumbbell-shaped bodies were formed, which then separated into two daughter protoplasts having a diameter of about 2.5 mu. Deoxyribonucleic acid and ribonucleic acid were halved during division. Penicillin inhibited the division of protoplasts, though the growth was not influenced by the drug. Membrane-bound amino sugar content was considerably reduced when the cells were grown in the presence of penicillin. These results suggest that organized murein formed on the protoplasts membrane may play an important role in the septation process.

Role of Submicroscopic Projections in Electrical Breakdown

Observations with an electron microscope and with a modified field-emission microscope verify the formation of submicroscopic, whiskerlike projections on the cathode surface, thus lending additional supporting evidence for the association of electrical breakdown with field emission from such sites. Several mechanisms for the formation of whiskers are identified. The predischarge current, with which the initiation of breakdown is associated, is observed to exhibit large fluctuations in the presence of contamination on either or both electrodes, and a tentative explanation is set forth in terms of a special proliferation of small protuberances.

Kilocycle Oscillations in an Electronegative Plasma†

ABSTRACT Observations have boon made of oscillations in the 100 key's region occurring in cold cathode d.e. iodine vapour discharges at. a pressure of approximately 0.2 torr. Variations of intensity and frequency with electrode separation and tube current were obtained, and variations of intensity with radial position in the positive column. The intensity of the oscillations showed considerable correlation with the occurrence of small protuberances at the edge of the cathode glow: suggestions are made about the nature of the oscillations in the main discharge which the protuberances appeal1 to generate, but. no definite conclusions have been reached.

Ciliary organelles and associated fibre systems in Euplotes eurystomus (Ciliata, hypotrichida). I. Fine structure.

Euplotes eurystomus bears 8 rows of single, non-motile simple cilia, 18 ventral cirri, and a row of adoral membranelles. Each cirrus contains 40-120 cilia in tight hexagonal packing, and each membranelle consists of 3 rows of 10-40 cilia; the component cilia adhere together in life, but no means of adhesion, other than small protuberances of the ciliary membrane, has been seen. The kinetosomes of compound organelles, but not of the simple cilia, are associated with rootlet fibres. The kinetosomes of the component cilia of compound organelles are linked together at two levels by characteristic arrays of fibres. Single rootlet microtubules (about 20 mµ in diameter) interconnect individual kinetosomes of adjacent membranelles, but the rootlet microtubules arising from cirri are found as bundles, each of which corresponds to one of the fibres seen in the light microscope. The bundles of microtubules of most cirri arise at dense bars near the edge of the cirrus base, and terminate at or near the pellicle, without interconnecting cirri directly or indirectly. The rootlet microtubules of the anal cirri run the length of the base of the cirrus near the inner end of the kinetosomes and join into large bundles; these run anteriorly to join with each other and attach to the distal end of the membranelle row. The anal cirri and the adoral zone of membranelles form one structurally united part of the locomotor apparatus.

Iodine positive-column oscillation associated with cathode instability

A positive-column oscillation in low-pressure iodine vapour with frequency about 100 kc/s has been found to be associated with oscillations of small corona-type protuberances of the cathode glow. Two ways are described for suppressing the oscillations.

Adhesive Wear of Fibers

In our previous paper, 1)2) the mechanism of wear phenomena of fibrous materials was classified into four types under various rubbing conditions. And the relationship between the wear resistance and its mechanical properties was described experimentally as follows;Amount of wear loss ∝total frictional force/modulus×tensile strength×elongationThe purpose of the present paper is to describe quantitatively the mechanism of adhesive wear. Adhesive wear takes place whenever two solid surfaces are in rubbing contact, whether lubricated or not, and remains when all other types of wear are eliminated, so that adhesive wear may be distinguished as the most fundamental of the several types of wear.In this analysis the number of contacts of small protuberances in the surface of fiber, I is assumed to be hm/u, where h is the depth of deformation of the surface, u is the distance between the protuberances, and m is a constant.(1) The general fomula for the relation between the real area of contact, A, and the load W is obtained as follows;A=C·Wm+2·φ/m+2·φ·λ (1)where λ=1 as plastic deformation, and λ=3/2 as elastic deformation and φ is a constant in reference to the shape of the protuberance, and C is a constant, (2) The general fomula for the relation between the volume of the worn material V and the load W is obtained as follows;V=C·WK (2)K=φ(ψ-1)+m/2·φ·λ+m (3)where ψ is a constant due to the shape of the worn particles.(3) In the case of polypropylene monofilaments, K seems to depend upon Young's modulus.(4) The temperature dependence of dead weight W/d under which the fibers are broken at a certain NB, shows maxima. In the case of log NB=4, the maxima appear at about 50°C and 100°C. The temperature dependence of W/d for adhesive wear and shaving wear presents similar tendency. Consequently, the temperature dependence of wear resistance in both the types of wear seems to depend upon its polymer properties.

Radar study of a hailstorm over Gauhati on 17 April 1962

On 17 April 1962 at 1520. IST, a hailstorm occurred over Gauhati Airport. Radar. scope pictures showed four strong echoes in a straight line moving towards the station from the west with different speeds. The nearest echo was overtaken by other three very near the station, and they merged into a single cell, showing a small blunt protuberance ill the rear. After a few minutes it developed into a hook as hailstorm broke over the station.

Studies on the Ontogeny of the Dwarf Mistletoes, Arceuthobium. III. Development of the Inflorescence

In vascular plants, the apical meristem of the shoot normally represents a continuation of growth in the apical meristem of the embryo itself. This is not the case in Arceuthobium. Here the shoot apex of the embryo is rudimentary and eventually dies after infection of the host occurs. The inflorescence of Arceuthobium is, therefore, an adventitious structure originating in the endophytic system rather than from the shoot apex of the seedling. Inflorescence buds arise in either of 2 ways. In some species (A. douglasii and A. americanum), buds first appear as small meristematic protuberances on the outer surface of cortical strands. In other species (A. campylopodum), the buds arise at the ends of short branches. The former, or diffuse, type gives rise to inflorescences along the entire surface of the host branch; in the latter, or condensed, type inflorescences are formed in clusters. Early ontogeny of the inflorescence apex of both types is described. Studies of subsequent growth of the inflorescence apex show 5 well-defined plastochronic stages: (1) maximal area stage; (2) minimal area stage; (3) early post-minimal stage; (4) late post-minimal stage; and (5) pre-maximal stage.

STUDIES ON THE ONTOGENY OF THE DWARF MISTLETOES, ARCEUTHOBIUM. III. DEVELOPMENT OF THE INFLORESCENCE

In vascular plants, the apical meristem of the shoot normally represents a continuation of growth in the apical meristem of the embryo itself. This is not the case in Arceuthobium. Here the shoot apex of the embryo is rudimentary and eventually dies after infection of the host occurs. The inflorescence of Arceuthobium is, therefore, an adventitious structure originating in the endophytic system rather than from the shoot apex of the seedling. Inflorescence buds arise in either of 2 ways. In some species (A. douglasii and A. americanum), buds first appear as small meristematic protuberances on the outer surface of cortical strands. In other species (A. campylopodum), the buds arise at the ends of short branches. The former, or diffuse, type gives rise to inflorescences along the entire surface of the host branch; in the latter, or condensed, type inflorescences are formed in clusters. Early ontogeny of the inflorescence apex of both types is described. Studies of subsequent growth of the inflorescence apex show 5 well‐defined plastochronic stages: (1) maximal area stage; (2) minimal area stage; (3) early post‐minimal stage; (4) late post‐minimal stage; and (5) pre‐maximal stage.

An Electron Microscope Study of Food Vacuoles in Paramecium aurelia

The foed vacuoles of Paramecium aurelia, when examined in the electron microscope, are seen to be surrounded by small secondary vacuoles 0.05 ‐ 0.2 μ. in diameter. Similar small vacuoles also surround the deepest part of the buccal cavity. Young focd vacuoles, i.e. those containing well preserved bacteria, are encircled by a smooth. vacuolar membrane. In older food vacuoles the vacuolar membrane in a transverse section often appears more wavy with small gulfs and protuberances. It is suggested that the small surrounding vacuoles are formed by the vacuolar membrane of older vacuoles by means of a process similar to pinocytosis. There is no evidence, however, that formation of small surrounding vacuoles takes place by pinocytosis in young food vacuoles. Examination of the cytoplasmic membrane of the deepest parts of the buccal cavity shows a similar prccess of vacuole formation by pinocytosis.

The physical chemistry of cell adhesion

An account is given of the many forces probably involved in cell adhesion and repulsion, and the relative importance of these forces is assessed. Calculations of repulsion barriers to adhesion between approaching cells indicate that villi and other small membrane protuberances are the most likely regions of initial contact. The change of relative importance of the various attraction and repulsion forces during shape changes, reversible adhesion and successive adhesions (e.g. in re-arrangement of aggregates) is not considered in any detail.

The Morphology of Leptodiscus terrestris, and the Function of Setae in Spore Dispersal

SUMMARYLeptodiscus terrestris requires light for the formation of both fruiting structures and conidia. The fruiting structure is meristogenous in origin. Branches are produced from an initial, multinucleate, hourglass-shaped cell. Sporogenous cells develop at the apex of each branch, and these in turn produce more sporogenous cells, eventually forming a thin, saucer-shaped fruiting structure.The spores first appear as small protuberances on the inner edge of the sporogenous cells. These protuberances enlarge and elongate and as they develop, they appear to be attached to the sporogenous cells by a very short stalk. This stalk disappears when the spores mature. When the spores reach their mature size, the setae are formed. The seta on the upper end of the spore develops at the point of greatest curvature toward the concave side, and the seta on the lower end develops at the edge of the slightly flattened surface near the concav side of the spore. One crop of spores is produced by the sporogenous cells each day. Spores are held together in a head by a mucilagenous substance.When the spores are in the head, the setae are folded back against the spore wall on the concave side. When the mucus is dissolved, the setae unfold and expell the spores outward with considerable force. The same mechanism of spore dispersal also appears to occur in Menispora tortuosa, a fungus with setulate conidia similar to those of L. terrestris.

不定芽形成にかんする研究

1. Vigorous adventitious bud formation was observed on the leaf rachises of the tomato plants abundantly fertilized and systematically trimmed.2. Adventitious buds appear only in the axillary parts of the petiolules of the middle and upper leaves.3. Under better conditions some of the buds develop into fruit-bearing shoots.4. Anatomical and histological investigations of the bud formation were made.5. Growing point of an adventitious bud is initiated in the subepidermal tissue of the leaf rachis as a small group of meristematic cells, which are produced by cell divisions of the subepidermal chlorenchyma.6. An adventitious bud appears at first as a small protuberance on the leaf rachis.7. A few leaf primordia and a typical vegetative cone are formed on the protuberance.8. Somewhat later the basal part of the bud grows longitudinally, and thus an adventitious shoot is formed.9. By cell divisions in the depth of the parenchyma the procambial strands extend downwards to connect with the conducting tissue of the leaf rachis.10. At later stages of development, the newly formed vascular system of the bud is seen completely jointed with that of the leaf rachis.

On Fretting Corrosion : Part 2, Analysis of the Mechanism of Wear

An analysis of the mechanism of wear is given and a general formula for the relation between the volume of the worn away material and the load is obtained. In this analysis the number of contacts of small protuberances in the surface is assumed to be xm/h, where x is the depth of deformation of the surface, h the mean distance between protuberances and m a constant. The general formula obtained is as follows : [numerical formula] where L' is the volume of the worn away material per unit length, W2 the load and y, m, p constants. This formula coincides well with the experimental relation L∝W0.7 which is mentioned in the first report. Discussions are given on the process of developing the oxide dust between the surfaces.

フークス科藻類の発生力学 XI

(1) Small clear protuberances grow and then are liberated from several parts on the surface of the unfertilized oosphere of Coccophora Langsdorfii. The number of the small bodies liberated was one to several. The central part of the small body can be stained with aceto-carmine, implying that the small body consists of nuclear substances.(2) The liberation of small bodies is considered to be the partial or total elimination of the superfluous haploid nuclei, which were born through the meiosis of oogonium. They are seven in number theoretically.(3) The liberation ceases about an hour after fertilization. This indicates that a change is taking place in the nature of the egg membrane after fertilization.

Ornithodoros arenicolous sp. nov. (Ixodoidea, Argasidae) from Egyptian Desert Mammal Burrows

An extensive survey of Egyptian mammal burrows from Mersa Matruh on the Western Desert, through the Eastern Desert and Sinai Peninsula, and as far south as Asyut Province, has revealed an obviously rare, undescribed species of Ornithodoros tick from widely scattered localities in this area. Adults of the new species are readily distinguished by relatively small size, large cheeks, irregularly and narrowly ridged integument which gives them a wrinkled appearance, short and sparse body hairs, absence of dorsal humps on tarsi, and presence of a small but distinct subapical dorsal protuberance on tarsi II, III, and IV. These distinctive characters readily separate it from 0. tholozani tholozani (Laboulbene and Megnin), apparently its closest relative.

Growth and Morphology of Tobacco Tissue Cultures In vitro

1. The growth in darkness of tobacco stem callus tissue on nutrient agar medium was investigated. Growth was studied during a period of 9 weeks in cultures taken from stock subcultures which were 6 weeks old. The experimental cultures were prepared by cutting the stock cultures into uniform cubes of two different sizes by a technique which is described. 2. Increase in size of the cultures resulted from the proliferation of small knoblike protuberances in which division and enlargement of cells was occurring very close to the surface. Knobs increased in number in two ways: (a) by cleavage and (b) by the formation of new growing centers in the subsurface of older knobs. An account of the histology of the growing cultures is presented. 3. Though uniform in initial size and under constant cultural conditions, the cultures within each series grew at different relative rates. Thus there were differences inherent in the initial culture pieces which determined the subsequent rates of growth of the cultures. 4. Ov...