The histopathological response of male game farm mallards fed lead, three types of plastic-coated lead, two lead-magnesium alloys, iron, copper, zinc-coated iron, and molybdenum-coated iron shot was studied. Mallards fed lead, plastic-coated lead, or lead-magnesium alloy shot developed a similar pathological response, including the formation of acid-fast intranuclear inclusion bodies in the kidneys. Birds fed iron or molybdenum-coated iron shot developed hemosiderosis of the liver. Two of four mallards fed zinc-coated iron shot also developed hemosiderosis of the liver. No lesions were found in mallards fed copper shot.

Neoplasms were found in 19 of 170 cottontail rabbits (Sylvilagus floridanus mearnsii) necropsied at the Wildlife Pathology Laboratory, Michigan Department of Conservation, 1950–1966. Nine tumors were benign; eight fibromas and one lipoma. Six malignant lymphomas, one nephroblastoma and three undiagnosed but apparently malignant tumors, also were found. Of particular interest is the high ratio of malignant to benign neoplasms. Gross and microscopic characteristics for the neoplasms are described and a case history involving a malignant lymphoma is discussed.

Deer sera collected during special post-season hunts were tested for group antibody to Chlamydia (psittacosis-human pneumonitis) antigen by the complement-fixation test. The deer came from one area in Quebec Province and two areas of New York State. Over 50 percent had complement-fixation titres greater than 1 to 16. Results of these tests are given along with a discussion of their probable implications in wildlife and human health.

A series of epizootics caused by Trichodina fultoni is reported. Fish kept in running water at 12°c showed severe signs of trichodiniasis. At 12 °C T. fultoni lacked strict host specificity, but demonstrated some preference.

A redescription of Tripartiella burstjormis, using the silver impregnated techniques, is given. This ciliate is reporred from Acantharchus pomotis. Trichodina nigra is reported from the same host.

To establish some of the factors responsible for neonatal fawn mortality in a white-tailed deer (Odocoileus virginianus) population on the Welder Wildlife Refuge in South Texas, radio transmitters, constructed as collars, were placed on 34 and 47 fawns, 1 to 12 days of age, during 1965 and 1966, respectively. The collared fawns were relocated almost daily with a receiver and a directional antenna for a minimum of a month, or until death.

Frequent relocation of collared fawns allowed observation of their physical condition and provided fresh carcasses enabling determination of the causes of death. In addition, it was possible to measure movements and study behavior during this normally inaccessible period.

Radiotelemetry techniques and problems encountered during the study are discussed. The utility of radiotelemetry in studies of juvenile mortality, movement, and behavior was amply demonstrated.

Studies of the pathogenicity for laboratory animals of organisms of the genus Chlamydia (psittacosis-LGV-trachoma group) recovered from diseased birds and mammals were extended to include three strains isolated from cows which had a history of encephalomyelitis or abortion. Each of the strains was titrated or passaged in chicken embryos, mice, guinea pigs, pigeons, turkeys, sparrows, parakeets and sheep. In terms of pathogenicity for these animals, one of the bovine abortion strains was identical to a previously studied pigeon strain in that it produced severe systemic disease indistinguishable from psittacosis in mice, pigeons, sparrows, parakeets and turkeys, while not affecting sheep or guinea pigs. The second abortion strain produced lesions in mice and chicken embryos only. The encephalomyelitis strain caused death and severe lesions in guinea pigs and dwarfing of chicken embryos but otherwise failed to affect the other test species. The “pathotype” determination may reveal significant epizootiologic relationships and may be useful in identifying the source of chlamydiae to domestic animals or in recognizing mutants with new pathogenic capabilities.