Size as a Criterion of Species in the Human Intestinal Amebae

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  • Amoebiasis Research Unit, Durban, South Africa


  1. 1.The influence of bacterial associates on the size of human intestinal amebae in culture is shown.
  2. 2.The use of size-distribution curves to distinguish amebae in controlled environments is described.
  3. 3.Evidence of a genetic size difference between E. histolytica and E. hartmanni is presented.
  4. 4.It is suggested that, until an accurate, practical method for separation is devised, a mean size of 10µ for cysts and 12µ for trophozoites (a criterion often suggested in the past), be used as the dividing line between the larger species, E. histolytica and the smaller, E. hartmanni.

Author Notes

The Amoebiasis Research Unit is sponsored by the following bodies: The South African Council for Scientific and Industrial Research, The Natal Provincial Administration, The University of Natal, The United States Public Health Service (Grant E-1592).