INTRODUCTION The description of tumors in invertebrates is rare. Smith in 1934 (4) described a mesenchymal tumor in the oyster (Ostrea virginica.) This tumor had arisen from the pericardium, was nodular or polypoid and consisted of large oval mesenchymal cells with an outer layer of simple columnar ciliated epithelium. A similar tumor was found in an oyster in 1887 by Ryder (2), and another tum...

Glochidia are the larval stage of freshwater unionid mussels that parasitize the fins and gill apparatus of fish. A total of 22 fish species were examined for the presence of glochidia whose distribution on individual hosts was studied on three common fish species, the roach Rutilus rutilus (L.), perch Percafluviatilis L. and bitterling Rhodeus sericeus (Pallas). Between 1997 and 1999, the fish...

from earlier experiments. Similar results were obtained for the freshwater bivalve Anodonta cygnea (Gade et al., 1975). In this animal, acetate and propionate were responsible for over 75 % of total accumulated end products after 30h of anaerobiosis. As volatile fatty acids can be stored in the animal in esterified form, some of the homogenates obtained in the experiments represented in Table 1...