Dr. Holló Ferenc szerk.: Parasitologia Hungarica 3. (Budapest, 1970)

prepatent period may last from 84 hours (

E.praecox

) to 7 days (

E.tenella

, E.necatrix

, etc.). 2. Exogenic development. Sporogony follows upon gametogony. Sporogony, i.e. the sporulation of the oocysts passed with the faeces to the outside world is completed in 1-2, exceptionally in 3 or more days. Since the conditions of experimental observation have been dissimilar

,in most cases it is rather supposed than verified that the sporulation temperature were 22-24° C. It would be more correct to state the sporulation time at a standard temperature with an internationally standardized method. Under natural conditions the sporulation time of oocysts depends largely on external temperature. GIEBEZDIN (1969) reports that in Turkmenia where there are extreme climatic changes, optimal sporulation of chicken coccidia in the soil took place in November, February and March. In these months the soil temperature did not rise above 26-32° C. At higher - 45° C - temperature, the oocysts failed to sporulate and deteriorated. Alternation of temperatures below and above the freezing point seems to be particularly deleterious to the oocysts. Under such conditions most of them deteriorate and only a very small proportion can complete sporulation. As to the size, the coccidium oocysts of gallinaceous birds correspond to the small or medium large types. Even E.max

ima

, whose name suggests extraordinary dimensions, may seldom reach 40^ in length. The cross sections of the sphaerical, subsphaerical, ovoid or elliptic oocysts are usually round but some species are exceptions. The oocysts of E.ventriosa are flat and this flattening is quite conspicuous under the microscope

,where the oocysts are seen to rotate slowly around their longitudinal axis in the fluid. Up to recently, the cyst walls of the eimerian parasites of gallinaceous birds were believed to be bilamellar. Newer in-