1.As Dientamoeba fragilis and Enterobius vermicularis occurred together in 20 times as many appendices as theoretically expected, it indicated some connection between the two species.
2.Sections of pinworms from a Dientamoeba-harboring appendix revealed the presence in many eggs of small, ameboid, uninucleate organisms, whose nuclei greatly resembled those found in uni- and binucleate D. fragilis from the lumen of formalin-fixed appendices. These bodies were not found in pinworm eggs from cases not known to harbor D. fragilis. Therefore, the pinworm appears to be a vector of D. fragilis.
3.Indirect evidence of transmission of D. fragilis in pinworm eggs is presented, but efforts to culture the ameba from eggs have not yet been successful.
4.Further evidence linking Dientamoeba with Histomonas meleagridis, the flagellate which causes blackhead in turkeys, is presented. This tends to confirm Dobell's hypothesis that D. fragilis is actually an aberrant flagellate rather than a true ameba and that its present classification is an error.
Present address: The Wellcome Research Laboratories, Tuckahoe, 7, N. Y.
Present address: Dept. of Pathology, The Menorah Medical Center, 4949 Rockhill Road, Kansas City, Mo.