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A Cytological Study of Ascus Development in Ascobolus magnificus Dodge

John L. Wood
Bulletin of the Torrey Botanical Club
Vol. 80, No. 1 (Jan. - Feb., 1953), pp. 1-15
Published by: Torrey Botanical Society
DOI: 10.2307/2482229
Stable URL: http://www.jstor.org/stable/2482229
Page Count: 15
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A Cytological Study of Ascus Development in Ascobolus magnificus Dodge
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Abstract

1. The theories of double fusion and brachymeiosis in the Ascomycetes and their present status are very briefly outlined. 2. Ascobolus magnificus Dodge, collected in Greenfield, Massachusetts, was isolated and grown to maturity in artificial culture. 3. A. magnificus is confirmed as a heterothallic species. 4. The cytological development of the ascus was followed with the aid of a modified propiono-carmine staining technique. 5. The phase-contrast microscope was found to be a valuable tool, when used in combination with carmine smears, for cytological studies. 6. Behavior of the nucleolus is described during nuclear divisions in the ascus and the presence of a nucleolus chromosome is reported. 7. Heteropyknosis was observed in the nuclei of the ascus. 8. There are apparently eight bivalent chromosomes at metaphase of the first division in the ascus. Approximately eight chromosomes were observed passing to each pole during anaphase of the third division in the ascus and the same number of chromosomes has been counted in the newly-formed spores. 9. No evidence of brachymeiosis was found during the present investigation of Ascobolus magnificus.

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