MITOSIS IN AMBA PROTEUS

¹ From the Department of Biology, the College of the City of New York

1. In Amba proteus the vegetative nucleus is a discoid, biconcave structure with a nuclear membrane, a layer of peripheral granules and a central endosomal mass.

2. During prophase the peripheral granules begin to disintegrate and the dividing chromatin originates from the endosome.

3. In metaphase the plate is fully formed and consists of numerous, small, deeply-staining chromatin granules. Spindle fibers, both inter-zonal and polar, are first apparent at this time. The interzonal fibers disappear at late anaphase. The polar fibers persist throughout the process.

4. The granules of the metaphase plate divide to form the two plates of the anaphase which continue to separate, becoming condensed and curved until the telophase stage.

5. The nuclear membrane is clearly present up to mid-anaphase and againat telophase. There is evidence that it persists throughout the entire process of mitosis.

6. The nucleus is fully reconstituted about five hours after cytoplasmic division. The peripheral granules are formed from the plate mass and appear a few minutes after division.