• Volume 45, Issue 6

      June 1957,   pages  263-313

    • Fossil foraminifera from the cretaceous rocks of South India - Part I. Ariyalur area orbitoids

      L Rama Rao

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      The author is now engaged in a detailed study of the fossil Foraminifera from the Cretaceous rocks of South India; the present paper deals with the Orbitoids found in a limestone band recently noticed near Ariyalur, in the Trichinopoly area. The abundance of these Orbitoids, together with plenty of associatedSiderolites, indicates that the containing rock is of Maestrichtian age and occupies a stratigraphical position in the Ariyalur group just below the overlying Niniyur Group (Danian). While some of the Orbitoids occurring here resemble certain species ofLepidorbitoides andOrbitocyclina already described, there are others which appear to be new. The paper gives a general account of these Orbitoids, drawing special attention to some of their interesting features. The probable significance of these in the study of the family Orbitoididae is briefly discussed.

    • Additions to the genusHansfordiella

      C V Subramanian

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      On the basis of a study of type material,Brachysporium bakeri Sydow andB. harunganæ Hansford are excluded from the genusBrachysporium Sacc., as typified by its lectotype species,B. obovatum (Berk.) Sacc.B. bakeri andB. harunganæ are considered to be congeneric withHansfordiella asterinearum Hughes, the type species of the genusHansfordiella and are transferred to that genus asH. bakeri (Sydow) Subram. andH. harunganæ (Hansf.) Subram., respectively. It is suggested thatHelminthosporium ?Puttemansii Arnaud (nomen nudum) may be aHansfordiella. A key to the five species ofHansfordiella is appended.

    • A study on the comparative effect of chemicals on chromosomes of roots, pollen mother cells and pollen grains

      Arun Kumar Sharma Santosh Kumar Sarkar

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      1. A comparative study of the action of Aesculine, Paradichlorobenzene and Resorcinol on the root-tip, pollen grain and pollen mother cell chromosomes ofNothoscordum fragrans Kunth. reveals considerable erosion and fragmentation at meta- and anaphase in root-tips.

      2. The division is mitotic in pollen grains but yet prolonged treatment resulted only in diplochromosome formation and not chromosome fragmentation. Fragmentation was also not observed in meiotic cells. Chemical treatment produced only irregularities in division such as lagging, non-disjunction and stickiness.

      3. The marked differences in response to chemicals between the root-tip cells on the one hand and the pollen grains and P.M.C.’s on the other is suggestive only of differences in chromosome metabolism and not the ultimate structure of the chromosomes.

    • Chromosome numbers in Indian medicinal plants

      R Sundara Raghavan

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      The paper deals with the chromosome numbers in some of the Indian medicinal plants. Of the twenty plants studied, the chromosome numbers of nine plants are reported for the first time. Five plants had numbers different from previous observations.

    • Root exudates in relation to the rhizosphere-effect

      K Bhuvaneswari N S Subba-Rao

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      Chromatographic study of the root exudates ofSorghum vulgare, var.dochna (Sorghum) andBrassica juncea (Mustard) revealed the presence of several organic acids and sugars in them. Although tartaric and oxalic acids,d-xylose andd-fructose were common to both, mustard had malic and citric acids,d-glucose and maltose in addition. The possibility of malic and citric acids as factors influencing the observed depression of the rhizosphere microflora of mustard plants has been suggested.

    • The routine-active oxygen consumption of the milk fish

      S V Job

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