JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. The American Society of Parasitologists is collaborating with JSTOR to digitize, preserve and extend access to The Journal of Parasitology. ABSTRACT: The life history of Echinostoma paraensei, a new Brazilian species with 37 collar spines, has been completed experimentally. The planorbid snail Biomphalaria glabrata serves as first intermediate host, and intramolluscan stages also develop in Physa rivalis. Sporocysts usually develop in the heart. Rediae are of two types, distinguishable by large or small pharynges. Cercariae released 25 or more days postexposure develop into metacercariae in the pericardial sac and kidney of snails, sometimes in various tissues of snails infected with rediae. Adults develop in hamsters, mice, or rats after they are fed metacercariae, but not in pigeons, chicks, or ducklings. The natural final host is not known. In recent papers (Basch and Lie, 1966; Lie, 1966a, 1967; Lie et al., 1965) we described the destructive antagonism of larval echinostomes to trematode sporocysts developing in the same snail. Various echinostome species naturally transmitted by Biomphalaria glabrata (Say) in Brazil are being sought and evaluated to determine their efficiency in destroying Schistosoma mansoni Sambon. This paper describes the life history of a new species of echinostome encountered during our studies.
MATERIALS AND METHODSCercariae of this species appeared in collections of B. glabrata snails made in Belo Horizonte (Bairro Sao Domingos), Caratinga, and Bambui, all in the State of Minas Gerais, Brazil. Snails were shipped by air to San Francisco, California, where we studied the life histories of their trematodes. Cercariae were permitted to encyst in laboratory-bred B. glabrata, and metacercariae were fed to hamsters and albino rats and mice. Eggs from washed hamster stools produced miracidia, which were used principally to infect laboratory-raised albino B. glabrata of a strain obtained from the National Institutes of Health, Bethesda, Maryland. Infected snails were kept in clear plastic, 1-gal aquaria at 24 to 27 C and fed on red leaf lettuce (Lactuca sativa). Techniques for the study of the parasite were the same as in previous studies (Lie, 1963a; 1965; 1966b, c). All measurements are in microns.
