Volume 54, Issue 2
August 1961, pages 57-112
pp 57-75 August 1961
New chemical constituents in a variety of Indian tobacco (N. tabacum) have been isolated by means of chromatography on alumina. The separation of four steryl glycosides, four sterols, one ketosteroid and nine waxy compounds have been reported in this paper. Attempts have been made to elucidate the chemistry of all these products.
pp 76-93 August 1961
1. A study of maturity and spawnings ofSillago sihama based on the detailed examination of 500 specimens of fish and their ovaries and also on casual observations of over a thousand females has been attempted in this paper. Preliminary observations on the condition of testes have also been made from 135 specimens.
2. The female fish have been classified as Immature, Maturing, Mature and Spent, with reference to the condition of their ovaries. The mature ovum contains a single oil globule generally measuring between 0·13 mm. and 0·15 mm. in diameter.
3. A study of the maturation cycle brought out three phases in the life of the fish:
4. The spawning period inS. sihama is of short duration and spawning takes place only once during the season.
5. The size of the femaleSillago at first maturity has been approximately fixed at 235 mm. in total length. The females were found to attain a maximum size of 354 mm. in total length.
6. The smallest male specimen with ‘mature’ testes measured 224 mm. The males attain a relatively smaller size, the maximum size noted being 273 mm.
7. The number of mature eggs liberated in a single spawning has been found to vary from 16,682 to 166,130 in sizes of fish ranging between 184 mm. and 340 mm. in total length.
pp 94-99 August 1961
The present studies deal with the bioassay of the persistence of insecticidal spray deposits on the cotton plant usingP. gossypiella as the test insect. Field-infested bolls were the main source for moth culture. Persistence studies were made by releasing moths in cages kept over treated cotton plants in pots. Mortality counts were taken every 24 hours till the residues lost their toxicity completely. Exposure period was 12 hours. A complete record of climatic conditions was maintained for the experimental period. 0·2% DDT and lindane, 0·1% endrin and gusathion persisted for 144, 96, 120 and 96 hours respectively.
pp 100-112 August 1961
The karyomorphology ofOryza australiensis, O. glaberrima andO. stapfii was investigated at the pachytene stage. It was found that the twelve chromosomes of all the three species are identifiable by the lengths, arm ratios and chromomeric pattern. A detailed description of each of the bivalents is given. The bivalents ofO. australiensis are considered to be more heterochromatic than those of the other two species. The present study indicated that the karyotypes of wild species,O. stapfii andO. australiensis, are more symmetrical than those of the cultivated species,O. glaberrima andO. sativa. The present study lends support to Nandi’s hypothesis that the basic chromosome number of the genus is 5. The karyotype ofO. australiensis is distinct by aggregation of chromomeres and the absence of supernumerary nucleoli.