The cell in development and inheritance . he spindle-poles are formed by twocytoplasmic masses derived, as Hertwig believes, from the intra-nuclear plates. Schaudinn (96, 3) likewise describes and clearlyfigures an intranuclear origin of the centrosome in buds of Acantho-cystis (Fig. 41), which are derived by direct division of the mother- 1 Cf. Calkins, 98, i, p. 388. DETAILS OF MITOSIS 95 nucleus with no trace of a centrosome. In this same form, asdescribed above, the ordinary vegetative mitoses are quite of themetazoan type, with a persistent extranuclear centrosome. The history of the chro
The cell in development and inheritance . he spindle-poles are formed by twocytoplasmic masses derived, as Hertwig believes, from the intra-nuclear plates. Schaudinn (96, 3) likewise describes and clearlyfigures an intranuclear origin of the centrosome in buds of Acantho-cystis (Fig. 41), which are derived by direct division of the mother- 1 Cf. Calkins, 98, i, p. 388. DETAILS OF MITOSIS 95 nucleus with no trace of a centrosome. In this same form, asdescribed above, the ordinary vegetative mitoses are quite of themetazoan type, with a persistent extranuclear centrosome. The history of the chromatin in the mitosis of unicellular formsshows some interesting modifications. In a considerable number offorms a more or less clearly marked spireme-stage precedes the forma-tion of chromosomes (diatoms. Infusoria, dinoflagellates, Eiiglypha);in others, long chromosomes are formed without a distinct spireme-stage {Noctiluca). It has been clearly demonstrated that in somecases these chromosomes split lengthwise, as in Metazoa {Noctiluca,.
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectcells, bookyear1902
