Abstract
Four species of Eimeria from fowls were able to develop in chicken embryos following the inoculation of sporozoites. Three species (E. brunetti, E. mivati and E. tenella) were able to complete the whole of their endogenous cycle in embryos. E. necatrix developed to late schizogony, E. acervulina and E. maxima did not develop.The life-cycles appeared to be delayed, and in the case of E. tenella embryo mortality was associated with heavy parasitism of the chorioallantoic membranes. Oocysts recovered from urate deposits in the allantoic cavity sporulated normally and induced infections in chickens.Attempts to infect turkey and quail embryos with E. tenella or chicken and turkey embryos with E. stiedae were unsuccessful.The implications of the findings are discussed.I wish to thank Dr C. Horton-Smith for his encouragement and guidance with this work; Dr M. E. Rose for help in the preparation of the manuscript and Mr B. J. Millard for careful technical assistance.