A Study of Somatic Chromosomes of both Sexes of the Common Indian Toad,Bufo MelanostictusSchneid., by a new Spleen Technique

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Abstract
A new colchicine squash technicque has been employed for the study of the detailed morphology of the chromosomes of B. melanostictus. The chromosome number and the morphology in the two sexes of the common Indian toad, B. melanostictus have been studied. The diploid number in both the sexes is 22 chromosomes. The chromosomes are of different shape and sizes. Most of them are submetacentric type but some of them are metacentric too. The claim made by earlier workers that all the chromosomes of different species of Bufo including B. melanostictus are only metacentric type, has been invalidated by the present study. The females are heterogametic sex and the X-chromosome has been determined to be about the fifth in the decreasing order of sizes and the Y is a small acrocentric chromosome which has been determined by comparing the idiograms of both sexes. A quantitative determination of the frequency of the arrested mitotic metaphase cells due to colchicine pre-treatment has been made. The results on the observation of the chromosome morphology, and sex chromosome mechanism have been discussed.