• Volume 9, Issue 6

      June 1939,   pages  323-374

    • Photoperiodism and the phasic development ofCrotalaria juncea

      B N Singh S N Singh

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      As the duration of light is increased above the normal the concentration of the total carbohydrates and nitrogen increases resulting in a diminished range of C/N ratio. A concomitant increase in the acidity value of the plant sap is observed with the length of the day. Accumulation of such metabolites appears to play an increasingly significant role in governing the initiation of the reproductive phase, in modifying the nature of the growth curve and thus inducing abnormalities in the organism.

    • The influence of moisture content and nitrate feeding on the nitrogen cycle in the soil both under aerobic and anaerobic conditions

      B N Singh S N Singh K M Nair

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      The paper deals with the influence of moisture content on ammonification and nitrification, and of nitrate feeding conditions of moisture and aeration on ammonification.

      A method is proposed for measuring ammonification. The proposed method for measuring ammonification based upon the difference in organic nitrogen both before and after the incubation period has been found to give better results for ammonification.

      There is a particular range of moisture content, both for optimum ammonification and nitrification, being between 34 and 51 per cent, of the moisture-holding capacity of the soil.

      Under saturated conditions nitrification is completely inhibited whereas ammonification continues though at a slower rate.

      Nitrates influence the ammonifying organisms to increased activity till a particular concentration is reached beyond which the process is retarded.

      The ratardation of ammonification is accompanied by setting in of denitrification.

      The ammonifiers seems to be composed of two groups, one aerobic and the other anaerobic in nature, if aerobic they exhibit facultative anaerobism under unfavourable conditions.

      Under aerobic conditions the activity of the ammonifying organisms is proportionately higher.

    • Observations on breeding in brackish-water animals of Madras

      N Kesava Panikkar R Gopala Aiyar

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      1. Breeding of animals of the brackish-waters of Madras is not particularly confined to any definite part of the year; actively reproducing species, especially the invertebrates, are met with during all seasons. In a good many forms there is intense reproductive activity during the rainy weather.

      2. The following types of breeding were noted :—

      1. Continuous breeding throughout the year occurring more or less uniformly and irrespective of seasons.

      2. Continuous breeding with marked season of higher activity in part of the year than in the remaining period.

      3. Breeding period confined to some definite part of the year.

      4. Discontinuous breeding occurring all through the year, breeding often taking place irregularly, mostly determined by the rains.

    • The internal ear ofScoliodon sorrakowah (cuvier)

      Shyam Sunder Lal

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      The author gives a careful and detailed account of the membranous labyrinth of the Indian sharkScoliodon sorrakowah, and both corrects and supplements the description of this organ given by Thillayampalam. Amongst the main inaccuracies in Thillayampalam’s account, may be mentioned the joining of the posterior and anterior semicircular canals dorsally to form a single tube, the position of the lagena distinctly ventral to the sacculus, the entire omission of therecessus utriculi and its nerve supply, the missing of the twoRamuli partis basilaris, and the notion that the posterior semicircular canal also, like the other two canals, communicates with the utriculus.

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