[Isospora from the domestic sparrow; multiplicity of species]

Natural intestinal infection of Isospora in the domestic Sparrow was studied during one year on a farm in Normandy. This survey showed many species and constant multiple infections. Some species were present all year, others were found only at certain times of the year; intensity varied with species and season. Almost all of the Isosporans previously described from the Sparrow were assigned to Isospora lacazei (Labbé, 1893), but this species is shown here in to be a parasite of the Goldfinch. Twelve new species are described on the basis of morphology of fresh sporulated oocysts. The most useful characters are those of: a) the Stieda apparatus and its inclusions;' b) the polar granules (number and shape); c) the residual body (diffuse or well delineated). In addition, the size and shape of oocysts and sporocysts, the number and shape of cristalloids in the sporozoites can be used to differenciate species. The following observations were made on sporogony: a) each species develops at a particular level in the intestine but several species could be found at the same level. However there is a patchy distribution of the species such that no two species occurred in the same villus. b) synchronous excretion of oocysts noted by others was found: the first oocysts appear at the beginning of the afternoon, the last at night fall; each species was found to have a characteristic and limited period of excretion. All the species found belong to the same systematic group (Stieda apparatus "macropylar") which suggests that they arose from successive speciations from a single species and were not acquired from other passerines in the same habitat.