Quarterly Journal of Microscopical Science, Vol s3-94, 445-460, Copyright © 1953 by Company of Biologists

Nuclear Transplantation in Amoebae. I

Some species characters of Amoeba Proteus and Amoeba Discoides

¹ Zoology Department, King's College, London, W.C. 2

1. The object of this work was to find characteristic differences between stock cultures of A. proteus and A. discoides in order to assess results obtained in experiments involving nuclear transplantation.

2. Previous work on the two species was not found to yield satisfactory diagnostic features.

3. Methods of establishing and maintaining clones and of observing living amoebae are described.

4. As a result of the study of outline drawings of active amoebae and of measurements of the largest diameter of the nuclei, two characters were found which enabled us to distinguish cultures of A. proteus and A. discoides. They were (a) the pattern of locomotion and (b) the distribution of nuclear diameters within a culture.

5. The outlines of active A. discoides tend to be more serrated than those of A. proteus. Outline drawings were readily sorted by independent observers into two categories corresponding fairly closely to the two species. By this method healthy cultures can be identified. Individual amoebae are not always identifiable.

6. An analysis of the longest nuclear diameters of amoebae of the two species showed that the average of a clone and the distribution of nuclear diameters within a clone are typical for each species and are little affected by the age and state of nutrition of the culture. The average nuclear diameter in our cultures, which was found to be independent of the nuclear size of the parent amoeba, was 45 µ (s. d. 5.6) for A. proteus and 38.2 µ (s.d. 3.6) for A. discoides.

7. The possibility is discussed of using physiological and serological, rather than morphological properties to distinguish between the species.