• Volume 64, Issue 5

      November 1966,   pages  231-282

    • Biological and oceanographic differences between the arabian sea and the bay of bengal as observed from the Indian region

      N K Panikkar R Jayaraman

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      The paper presents some of the important differences in the oceanographical and biological conditions in the waters of the Arabian Sea and the Bay of Bengal along the Indian coasts. In discussing the biological variability of the two environments from the point of view of fishery productivity, attention is particularly drawn to the extremely complex nature of the oil sardine and mackerel fisheries, especially along the west coast of India, which accounts for the bulk of the fish landings. An attempt is being made to provide a suitable explanation for this on the basis of the nutrient distribution pattern associated with the occurrence of seasonal ‘upwelling’. It is also pointed out that the ‘upwelling’ processes along the west coast of India are also of a complex nature and the forces leading to this are yet to be properly understood. Some comparison is drawn between the conditions on the south-west coast of India and some of the classical upwelling regions of the world, particularly with reference to two important features, namely, formation and disappearance of temporary banks of mud and the occurrence of special planktonic blooms often leading to mass mortality of fish.

    • Embryology ofVeronica serpyllifolia L.

      Govindappa D Arekal

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      The young microsporangial wall ofVeronica serpyllifolia L. is made up of four layers of cells, the innermost being the glandular tapetum. During later stages the tapetal cells become binucleate, the middle layer breaks down and the endothecial cells acquire band-like thickenings on their tangential walls.

      Quadripartition of the microspore mother cells is simultaneous. The pollen grains at the time of release are two-celled.

      Development of female gametophyte in the unitegmic, tenuinucellate, hemianatropous ovules conforms to the Polygonum type. An endothelium surrounds the middle part of the mature embryo sac.

      The endosperm isab initio cellular and is haustorial. The chalazal haustorium is unicellular, binucleate and tube-like. It comes in contact with the terminal end of the conducting strand of young seed. The micropylar haustorium, made up of two binucleate cells to begin with, becomes a 4-nucleate body after cell-fusion. The extension of this haustorium is intercellular in the initial stages but becomes intracellular in later stages and comes in contact with the conducting strand near the micropylar part of the seed.

      Development of the embryo conforms to the Crucifer type. The celld functions as the hypophysis.

      The embryological data obtained in the study have been evaluated in the light of previous work in the tribe Digitaleae.

    • Colchitetraploidy inDolichos lablab Linn

      N K Sen Yashodanandan Pandey

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      Four strains ofDolichos lablab Linn. were treated with 0·5 per cent. aqueous solution of colchicine for 6 and 9 hours. Both the treatments were more or less equally effective.

      Polyploid plants had bigger, thicker, coarser and dark green leaves. The increase in thickness was due to increase in palisade tissue.

      Colchitetraploids had reduced fruit setting with shorter pods which contained fewer seeds. Many empty pods, sometimes with very small deformed seeds, were also found. The seeds in colchitetraploids, although variable in size, were generally bigger and heavier except in strain DL 279. Nearly 40% seeds were shrunken.

      The zygotic number of chromosomes in the diploid and tetraploid is 22 and 44 respectively. Meiosis in diploids was regular. In tetraploids different chromosomal configurations from uni- to quadrivalent were seen. Laggards and precocious movements of chromosomes were conspicuous features and were more common in DL1458 and BR19 strains.

    • Riebeckite syenite from Idamakallu-Racherla, Kurnool dist., Andhra Pradesh

      B Somasekar B S Machigad C Naganna

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      The study of the riebeckite syenite from Idamakallu-Racherla area shows interesting textural and microstructural features. Based on the petrographical and petrochemical evidence, it is surmised that a rock, which was originally a hornblende syenite, has been transformed into riebeckite syenite through soda-metasomatism. The way in which the mineral transformations took place and the secondary minerals have developed is discussed.

    • Symptom expression, virus concentration and respiration in the leaves ofDolichos lab lab infected with dolichos enation mosaic virus

      A Ramadasan

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      InDolichos lab lab infected with Dolichos enation mosaic virus (DEMV) symptom expression is more severe in winter than in summer, while relative virus concentration, assayed serologically, is higher in summer than in winter. The virus concentration reaches its highest peak on the 8th day after inoculation in the first trifoliate leaves that emerge after inoculation of primary leaves, thereafter reaching the lowest concentration on the 10th day in all the leaves.

      Respiration is higher in the infected leaves during the initial increase in the relative virus content. But when the concentration of virus is highest (on the 8th day), the rate of oxygen uptake is significantly lower than in the healthy controls. Thus the sudden decrease in the virus concentration on the 10th day is preceded by a low rate of respiration on the 8th day, when the RQ also is much lower in the infected tissue than in the corresponding healthy controls.

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