Dr. Kassai Tibor szerk.: Parasitologia Hungarica 1. (Budapest, 1968)

Their shape was generally round, hut often ovoid or ameboid. In later studies on both types of liver lesion one or other parasite was noted without apparent relationship to the type of lesion. The macroscopically distinguishable liver lesions showed no corresponding variation of microscopic structure. In the liver parenchyma necrotic foci with karyolysis and subacute inflammation of the adjoining tissue were found. The foci did not become encapsulated by fibrous tissue;only a slight increase of connective tissue being noted in inflammatory areas around the blood vessels and biliary ducts. Besides infiltrating lymphocytes and mononuclear cells these inflamed areas contained many eosinophilic and pseudoeosinophilic cells. Granulocytes and numerous giant cells were also found. In the affected areas the lumina of blood vessels and sinusoids were distended with red blood cells (Fig. 5). In the present examinations the parasites considered to be the etiological agent of blackhead were of two morphologically distinct types. They occurred either singly or in groups (nests), most of them, int ere v-llularly

. One type,a round structureless body of 7-11 s* diameter, stained vivid red with Mallory's stain. Staining positively with PAS, it was very likely a fungus. The other type, staining pale pink with eosine, appeared as single or multipe roundish bodies surrounded by a clear ring (Pigs.3a,3b, 4). Mallory's stain imparted to them an uncertain greyish hue. They were larger than the fungus-like organisms

,-of slightly ovoid shape and some had diameters above 40 Occasionally they were seen in an apparently intracellular position,adjacent to the enlarged and flattened nucleus of the host cell. Some of the parasites showed one or more tiny bright ruby-red granules, surrounded by a clear halo-, situated close to the nucleus. The occurrence of such granules seemed to be associated with division of the parasite. Single granules were usually seen close to the nucleus, whereas when several granules were present they were distributed in the cytoplasm,sometines with obvious signs of cell division around them. In larger parasites the clear halo was mere