• Volume 34, Issue 1

      July 1951,   pages  1-61

    • Placentation in the sea-snake,Enhydrina schistosa (Daudin)

      L R Kasturirangan

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    • Polygalacturonase activity ofAspergilli

      M S Pavgi H R Pithawala G R Savur A Sreenivasan

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      1. Three strains ofAspergilli having good PG activity were isolated.

      2. The conditions for maximum elaboration of PG were studied using synthetic liquid media as well as wheat bran.

      3. The enzyme content was maximum after 4 days of growth; pH below 5 favoured the formation of enzyme.

      4. Wheat bran was a better substrate than synthetic liquid media; aqueous glycerine was very satisfactory for extraction of the enzyme from wheat bran medium.

      5. Partially purified PG preparations were obtained by precipitating enzyme at 60 per cent. concentration of ammonium sulphate after discarding the precipitate at 20 per cent. salt concentration; alcohol inactivated the enzyme to a great extent.

      6. The optimum pH for activity with citrus pectin as substrate was about 4–5; hydrolysis was rapid during first 12–24 hours and decreased thereafter during a further 8–10 days period.

    • Some aspects of regeneration in leaf cuttings of tomato

      R S Choudhri V B Bhatnagar

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      1. Rooting in leaf cuttings is not confined to callus region of the petiole or petiolules but can extend to considerable distances if conditions are favourable.

      2. Regeneration in leaf cuttings of tomato is apparently not different than found to occur in other plants.

      3. Terminal dominancy in tomato as suggested by Isbell cannot be taken as a rulé as both shoot and root could arise by the same organ irrespective of position and perhaps at the same point.

      4. In case of tomato, perhaps, full regenerates could also be produced from leaflets alike leaves.

    • Minor elements in soil and their effect on forage and feeding cattle with special reference to their significance as tracers of evolution of some complex organic structures: as determined by application of goldschmidt’s law

      B Rama Moorthy

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      There are many gaps in our knowledge of the biological interrelationships and antagonisms of the trace elements. For example, there are certain animal deficiency diseases of Cu and Co which plant analyses for these elements do not reveal unless there is an understanding of the elements which antagonise them and of those related.

      The application of Goldschmidt’s law to the replacements of atoms and ions in complex crystal structures (in the form that such replacements are possible only when the size of the atoms concerned agree within 10% of each other) coupled with a knowledge of the changes in valency and oxidation reduction systems involved, has been shown in this paper to elucidate many of these relationships and antagonisms.

      The essentiality of Cu and Co for hæmoglobin formation, the cause of anæmia due their deficiencies and how they are antagonised by Mo are shown, as also the essentiality of Mo for N fixation and the antagonism between Cu and Pb in the sway-back diseases. The essentiality of Fe, Cu. Mn and Mg for chloryphyl formation and the possible steps in the evolution of chloryphyl and hæmoglobin from cytochrome by the combined action of intermediary metal atoms have been traced along with the biological antagonism between Se and S. A consequence of this is the greater importance of Mo for leguminous plants compared to others with a tendency for the deficiency in cattle of Cu in countries where legumes and the like are extensively grown.

    • Chromosome evolution in wild populations of acrididæ - Part I. On the occurrence of a supernumerary chromosome inAiolopus sp.

      S P Ray-Chaudhuri G K Manna

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      1. Two individuals out of a total of 26 specimens ofAiolopus sp. ‘B’ examined cytologically showed in all the dividing cells of their testes a super-numerary chromosome of about one-third of the size of the X.

      2. The normal diploid number in the species is 23 and it has an XX-XO mechanism of sex-determination.

      3. The additional chromosome never forms a chiasma with any member of the normal chromosome set, but it has been found, in about half of the diplotene and diakinesis nuclei, to be associated with the X chromosome.

      4. The supernumerary chromosome segregates without division independently of the X in the first meiotic division and divides equationally at the second meiotic division. As a consequence of this behaviour, it is regularly included in half of the sperms produced.

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