a1 From the Molteno Institute, University of Cambridge
1. Histomonas meleagridis was isolated in culture from the liver lesions of a hen suffering from “blackhead” (enterohepatitis). It has been cultivated at 36·5–37°C. for over a year.
2. Chicks, which had been reared free from protozoa, were inoculated per os or per anum, with cultures of the above strain of H. meleagridis. Eleven out of twelve birds became infected. Caecal lesions only were produced. This strain, although isolated from the liver lesions of a hen suffering from acute blackhead, showed no abnormal virulence in chicks.
3. Individuals of this strain of H. meleagridis showed amoeboid movement but were also flagellate. Normally the protozoon was uninucleate, but binucleate forms were common, and tri- and quadrinucleate forms occurred more rarely. One flagellum arose from each nucleus.
4. During division the flagellum disappears. The method of nuclear division was similar to that of Trichomonas.
5. A resistant phase was never seen in the cultures.
Research Fellow of Girton College