• Volume 54, Issue 4

      October 1961,   pages  169-208

    • Embryogenesis inSphenoclea zeylanica

      B G L Swamy D Padmanabhan

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    • Observations on dual phenomenon in Aspergillus

      J N Rai J P Tewari

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      Two soil-inhabiting strains ofAspergillus niger van Tieghem have been found to showDual phenomenon, i.e., separation of the thallus into M-, C-and MC-types. Temperature of incubation has been found to effect such changes in the thallus and governs the pattern of separation. MC-type of one of the strains has a tendency to change its normal conidial apparatus to a state where thick-walled, smooth and hyaline bodies are produced in chains directly from the hyphal tips. A naturally occurring soilMycelia sterilia has been found to be identical with M-type of one of the strains.

    • The responses ofDasychone cingulata grube to photic stimulation

      R Theodore Srinivasagam

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      1. When kept in light,Dasychone cingulata Grube exhibits two types of movements: (i) complete retraction into the tube and (ii) movement of the branchial crown or branchial filaments.

      2.Dasychone contracts into its tube when a shadow is passed on it. This behaviour is more pronounced in the higher intensities than in the lower intensities of light. It not only responds to a decrease but also to an increase in intensity and the contraction to a passing shadow is greater in a white background than in a black background.

      3. Adaptation to continuous passing of shadows is rapid. Dark adapted forms readily respond to shadow than the light-adapted forms and the duration of adaptation in any particular intensity is also correlated to it.

      4. The range of spectral sensitivity is wide inDasychone but is least sensitive in red light.

      5. The above experimental results as well as the significance of the contraction ofDasychone into its tube have been discussed.

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