An examination of oocysts in samples and isolates originating from the faeces or gut contents of 582 wild wood-mice (Apodemus sylvaticus), yellow-necked mice (A. jlavicollis) and bank-voles (Clethrionomys glareolus) revealed 7 different species of the genus Eimeria. Of these, E. divichinica Musaev & Veisov, 1963, E. apodemi Pellhrdy, 1954 and E. hungaryensis Levine & Ivens, 1965 are recorded from British wood-mice, and E. rysavyi Levine & Ivens, 1965 from British bank-voles for the first time. Two additional species from the wood-mouse, E. montgomeryae n.sp. and E. uptoni n.sp., are described. The species E. divichinica, E. apodemi, E. hungaryensis and E. uptoni were also found in the yellow-necked mouse. The pre-patent times of E. apodemi, E. hungaryensis, E. montgomeryae and E. divichinica were established by passage in the wood-mouse.

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SUMMARYThe fine structure of the developing macrogamete of Eimeria maxima was studied from chicks killed at intervals from 138 to 147 h after inoculation. The macrogamete developed within a parasitophorous vacuole. Lying within this vacuole and extending for some distance around the periphery of the macrogamete were intravacuolar tubules, grouped in certain areas, and in some cases they were seen to make direct connexions with the cytoplasm of the parasite. During development, electron-pale vesicles were pinched off externally from the surface of the macrogamete. There appeared to be 2 forms of wall-forming bodies of the Type I during development, one form being less osmiophilic than the other. Other organelles present, such as wall-forming bodies of Type II, granular endoplasmic reticulum, mitochondria, canaliculi, lipid inclusions and intravacuolar folds, were similar in structure to those of other Eimeria species.

Five new species of Eimeria are described from lizards. Eimeria baltrocki n. sp. was found in the berber skink, Eumeces schneideri, from Egypt. The o6cysts are cylindroidal, averaging 38 x 18.3/xm, with a single thick oOcyst wall. Most oOcysts possess a single polar granule; a micropyle and o6cyst residuum are absent. The sporocysts are ellipsoidal and average 11.5 x 8.

SUMMARYOocyst wall formation in Eimeria maxima was studied during the macrogamete stage in intestinal cells of the chick and in unsporulated oocysts isolated from faeces. The outer of the 2 membranes bounding the mature macrogamete separated from the surface but remained as a veil surrounding the developing oocyst throughout the whole intracellular process. Wall-forming bodies Type I were initially applied to the limiting membrane of the zygote cytoplasm; a layer of material similar to their contents was then formed around the zygote. As this occurred a new double membrane was formed surrounding the oocyst cytoplasm. The outer wall layer was initially homogenous in appearance but later developed into 2 zones, an outer amorphous region and an inner osmiophilic region. The inner layer of the oocyst wall was formed from the contents of the wallforming bodies Type II which dispersed between the outer wall and the limiting membranes of the oocyst cytoplasm. There was evidence of an additional membrane formed external to the outer wall. The outer membranes were not present around the wall of oocysts passed in the faeces of chicks, but the same wall zonation was evident, although the inner osmiophilic zone of the outer wall layer was markedly thinner in comparison with the same zone seen in the tissues.

Four species of wild rodents from the British Isles, Myocustor coypus (the Coypu), Apodemus sylvaticus (the Wood mouse). Mus musculus (the House mouse) and Clethrionomys glureolus (the Bank vole) were examined during 1918 and 1919 for the presence of coccidian parasites of the genus Eimeriu. From an examination of 852 faecal samples a total of 14 species of Eimeriu was found. Species identification was based mainly on the morphology of the sporulated oocyst. The number of host species examined and the overall prevalence of infection were as follows: 252 M. coypus (45·6% infected), 471 A. sylvaticus 56·5%), 59 M. musculus (42·4%) and 70 C. glureolus (22·9%). The results are compared with previous surveys and discussed in the light of the general knowledge concerning coccidial infections. The present work showed that prevalence of infection in the wild rodents studied may be influenced by the age, weight and sex of the host, and by season.

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The ultrastructure of the epimastigote of Trypanosoma cobitis in the crop of the leech vector Hemiclepsis marginata is described. Microorganisms, closely resembling endosymbiotic bacteria, seen in monoxenous trypanosomatids, were present in the cytoplasm. Also, within the cytoplasm were ribosomes, sparse endoplasmic reticulum, a Golgi apparatus, and a wide variety of other inclusions, in particular multivesiculate bodies which appeared to contain waste material. The well-developed branched mitrochondrion had platelike cristae and an expansion near the nucleus which contained the kinetoplast DNA. A cytostomal opening situated near the flagellar pocket leads to a cytopharynx surrounded by five microtubules.