• Volume 30, Issue 6

      December 1949,   pages  307-368

    • Lower epidermis of leaf midrib as an imdicator of its hardness in sugarcane

      K L Khanna S L Sharma

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      1. Number of Silica cells per unit area in the lower epidermis of leaf midribs of thirteen varieties of sugarcane, covering a wide range of hardness of leaf midribs was noted. P.O.J. 2725,Sewari (Nargori group) and Co 299 had on the average, 39·4 to 41·4 of them in a circular field which was 470 µ in diameter, whereas in Co 331, Co 513 andChin (Saraitha group) the number was as low as 13·3 to 14·5 in the same area.

      2. Silica cells were found to have no consistent association either with the weight required to puncture the midrib on its convex side or with the thickness of the outer cell wails, both the correlation coefficients being too tow to be significant even at 10%, level.

      1. The range of the thickness of outer walls of long cells in the epidermis as expressed in the divisions of the eye-piece micrometer was from 14·5 inSewari (Nargori group) to 23·5 in Co 421 (I division = 0·22µ).

      2. The varietal differences were significant at 5% level.

      1. Weights required to puncture a midrib varied from 598 gm. inChin to 1273 gm. in Co 285 and these for the varieties studied were found to be significantly different at 5% level.

      2. The correlation coefficient between this character and the thickness of cell walls was found to be + 0·6377 which was significant at the same level.

      3. The thickness of outer wall of long cells of lower epidermis could, therefore, be used as a fairly reliable indicator of the puncture-weight and, therefore, of the hardness of a leaf midrib.

      4. The erratic behaviour of four varieties, namely Co 285, P.O.J. 2725,Chin andSaraitha (Saraitha group) in which the puncture-weights were found to be bisher or lower than those warranted by the thickness of cell walls was explained by the size and number of vascular bundles and the sclerenchymatous cuchions together with the thickness of sclerenchymatous cell walls when these characters were considered in relation to the size of a midrib in cross-section. All the four varieties were found to be abnormal for one character or the other.

    • Influence of vitamin C and oxidising agents on prothrombin

      K V Giri P Seshagiri Rao A Rahman

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      Vitamin C, copper and vitamin C—Cu complex had no inhibitory effect on prothrombin activity, the lack of inhibition being due to the stabilization of the vitamin by the protective factors associated with the enzyme.

      While hydrogen peroxide had no effect on prothrombin activity, iodine and sodium thiosulphate were found to inactivate prothrombin, the activity in both the cases being regenerated by passing carbon dioxide. Reducing agents like sodium sulphite, however, did not regenerate the prothrombic activity lost by treatment with iodine.

      The organic solvents, chloroform and carbon tetrachloride were found to have neither activating nor inhibiting effect on prothrombin.

      The presence of traces of fibrinogen along with prothrombin appears to be necessary for the stability of the enzyme.

      The results have an important significance in throwing new light on the nature of the prothrombin and the mechanism of blood coagulation.

    • Vitamin C content of lucerne and the factors controlling its stability

      M A Sahadeo P Seshagiri Rao Sudha Deolalkar K V Giri

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      Lucerne (alfa alfa) is found to be a very rich source of vitamin C containing 1·78 mg. of the vitamin per gramme of the fresh lucerne as judged by the usual dye-titration method and Lugg’s formaldehyde method.

      Lucerne loses more than 80% of its vitamin C on drying either in direct sunlight or under the fan at 25° C.

      Lucerne contains a feeble oxidase system and a powerful protective factor, which is very thermostable and which is associated partly with the colloidal and dialysable portions of the juice.

      The protective factor is isolated free from the oxidase system and it is found to annul the non-cupric and cupric ion oxidation of vitamin C, without having any effect on the enzymic oxidation of the vitamin.

    • Control of “red ants” (Oecophylla smaragdina Fab.)

      K N Trehan G M Talgeri S R Dhareshwar

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    • Active elongation of unstriated muscle during inhibition, accommodation and relaxation

      Sunita Inderjit Singh Inderjit Singh

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      1. Dog’s stomach muscle and the human appendix relax actively after being stimulated.

      2. Dog’s stomach muscle relaxes actively during inhibition and accommodation.

      3. Relaxation is of two kinds, active and passive.

      4. Active relaxation is diminished by asphyxia, cyanide and partially restored by glucose.

      5. Active relaxation is diminished by iodoacetic acid.

      6. Active relaxation is diminished by substances that produce tonic contraction, such as potassium, ammonium, lithium, sodium, barium, hydrogen, ions, calcium, strontium, magnesium, bromide, nitrate, iodide, thiocyanate, acetylcholine, pilocarpine, nicotine, eserine, adrenaline.

      7. Methyl and ethyl alcohols diminish active elongation in small and increase in large concentrations.

      8. Active elongation is diminished by hypo- and hypertonic solutions.

      9. The optimum pH for active elongation is 8.

      10. The optimum temperature for active elongation is 30° C.

      11. Substances that depress the vitality of the muscle cause contraction by antagonising active elongation.

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