Observations on Entamoeba histolytica

Abstract

1. Observations on E. histolytica from the human intestine have been made and compared with amoebae living in culture media and in the ulcers of the large intestines of cats, which have died of amoebic dysentery.2. The effects of the substances chlorine, tyrosin, and skatol on culture amoebae have been investigated; it has been found that the two first substances stimulate vegetative reproduction, but that skatol induces cyst formation.3. The changes that the nucleus undergoes preparatory to division and the behaviour of the karyosome during division are fully described. It is shown that the nuclei originally described as characteristic of E. histolytica and E. tetragena are phases of nuclear change in the life history of the same animal.4. Cyst formation and the nuclear divisions in the cysts are described, together with a short discussion as to the view taken that the chromatoid bodies are not comparable with the chromidia of other Rhizopoda.5. Reasons are adduced for the suggestion that during the further development of the cysts quadrinucleate amoebae emerge, which divide to form four small amoebulae.6. Degeneration in E. histolylica is described and the view of Darling, that budding phenomena are degenerative ones, is confirmed.