Published online by Cambridge University Press: 06 April 2009
1. Examination of dividing trophozoites of E. invadens revealed that the peripheral granules did not contribute directly to the formation of chromosomes. Material for the chromosomes seemed to be derived from the karyosome and the perikaryosomal particles. No centrioles and spindle mechanism were noticed.
2. The nucleus showed Feulgen-positive material at all stages; in the interphase the reaction was faint because of the poor staining of the karyosome and widely dispersed perikaryosomal particles. The intensity of the staining reaction increased with the onset of division and continued so till late anaphase.
3. Nuclear division in the cyst was found to be different from that of the trophozoites and involved the formation of a typical spindle.
4. Karyosomes of the nuclei of the uni-, bi-, tetra-nucleate cysts were all positive to Feulgen staining.
5. Observations on amoebae undergoing cytokinesis showed that the process of division supports the amoeboid movement theory of cleavage put forward by Chalkley (1935, 1951).
Thanks are due to Dr P. Tate for constant guidance and encouragement during the course of this work and to Dr E. W. McConnachie for kindly giving the cultures and for critically reading through the manuscript. The work was carried out during the tenure of a Royal Society and Nuffield Foundation Commonwealth Bursary.