• Volume 51, Issue 2

      February 1960,   pages  57-102

    • Induction of polyploidy in watermelon

      V L Chopra M S Swaminathan

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      Several colchicine treatment methods were tried in the varieties Farrukhabadi and Asahi Yamato of watermelon in order to induce chromosome doubling in them. Treatment of seedlings by drop method in the cotyledonary stage with an emulsion comprising 0·2% colchicine, stearic acid, morpholine and lanoline gave the highest percentage of affected plants (38·59%). Next in efficiency was the periodic application of drops of 0·4% colchicine on the growing point. The tetraploids had all the usual characteristics associated with autopolyploidy and during meiosis in a microsporocyte 11 quadrivalents were observed. The mean frequency of quadrivalents per cell was 5·91. Seed fertility in tetraploid watermelon was much reduced and from 4x×2x crosses in Farrukhabadi one fruit containing 67 seeds was obtained. The 3x seeds germinated only when the seed coat was partly removed and the fruit set on a 3x plant had seeds without embryo. There appears to exist genetic variability with regard to the ability of a strain to yield a completely seedless triploid and it is consequently necessary to produce triploids of many varieties and select the desirable ones for the commercial production of seedless watermelon.

    • The yeast nucleus

      M K Subramaniam

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      The disagreements on the question whether the nucleus of yeast is an organelle unrelated to the vacuole or whether it is the vacoule itself (Pictographic Summary I, 1844–1956) is only a corollary to the limitations of fixation and staining procedures carried out on cells in which the former was invisible. A reconciliation is possible if investigations are confined to cells in which both the organelles are visible. The extra-vacuolar nucleus has a conventional vesicular structure with a nuclear membrane, chromocenters and nucleolar equivalents. The vacuole, which has a limiting membrane in older cells, is Feulgen negative and segregates neutral red in living cells. It is therefore a cytoplasmic inclusion. A strict comparison of living with stained preparations is presented inPictographic Summary II, 1956.

    • Observations on the ossification centres ofTrichopodus trichopterus (Pall.)

      V B Marathe D V Bal

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    • Three new species of braconidae from India

      B R Subba Rao A K Sharma

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    • Experimental cutaneous lesions in the albino rat

      Najoo D Maloo M V Radhakrishna Rao

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      This investigation was undertaken to elucidate the actiology of ‘phrynoderma’. Two experiments were conducted, one the study the effect of vitamin A deficiency and the other, to study the part played by fat in the production of cutaneous lesions in rats.

      It is concluded that deficiency of vitamin A in conjunction with deficiency of essential fatty acids, plays an important role in the production of cutaneous lesions in rats resembling those in ‘phrynoderma’. It is suggested that ‘phrynoderma’ may be due to the combined deficiencies of both these factors. The experimental evidence further points out, that lack of vitamin A plays a larger role in the production of cutaneous lesions resembling ‘phrynoderma’.

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