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VEGETABLE CELLS.
case, that the primary nucleus does not become dissolved,but that it is this which becomes divided.
4. Four nuclei are produced, probably by the divisionof the primary central nucleus into two, each of whichbecomes again divided. The four nuclei assume a tetra-hedral arrangement. The contents separate into four por-tions, each of which contains one of those nuclei in itscentre. The parent-cell divides by parietal cell-formationinto four tetrahedrally-arranged secondary cells. I havehitherto only observed this process in the new single-celled genus of Algae Tetrachococcus*
5. The lateral ( primary) nucleus of the parent-cell be-comes absorbed. A new secondary nucleus makes its ap-pearance in the centre of the parent-cell. At its sidesoriginate two smaller nuclei.
a. The secondary nucleus of the parent-cell becomes ab-sorbed. The contents separate into two portions, each ofwhich contahis one of those smaller nuclei in the middle.The parent-cell divides by parietal cell-formation into twocells with central nuclei. Each of the two nuclei dividesinto two nuclei, and each of the two cells divides againinto two secondary cells by parietal cell-formation.
b. The two small nuclei divide, so that now four stillsmaller nuclei lie around the large secondary nucleus inthe parent-cell.
a. The secondary nucleus of the parent-cell becomesabsorbed. The four small nuclei assume a tetrahedral ar-rangement. The contents separate into four portions, eachhaving one of these four nuclei in the centre. The parent-cell divides by parietal cell-formation, into four tetrahe-drally-arranged cells with central nuclei.
b. Some, or all of the four small nuclei divide, so thatthen from five to eight still smaller nuclei lie around thelarge central secondary nucleus of the parent-cell. Thelatter becomes absorbed. The contents separate into justas many portions as there have been small nuclei produced,