Studies on a small collection of planorbid snails from southern south America

Abstract

Part of the snails was extended with menthol crystals and fixed locally in alcohol 70%, while some other specimens were brought alive to the laboratory in Recife where the present studies were made. Upon arrival the alive snails were put in tanks to breed. Preserved snails were dissected for classif ication. Alive snails were each exposed to ten miracidia of a local strain of Schistosoma mansoni. In ali the infection experiments a highly suseeptible strain of Biomphalaria glabrata, from Paulista (Pernambuco), was used as control.Snails exposed to the infection were kept in tanks and examined for cercariae by exposition to a strong source of light beginning the 20th day after the infection After 40 days the snails were crushed and examined for infection.The temperature of the water, during the experiments, varied from 24 to 26°C.The following studies and observations were made. PARAGUAY Twenty-one snails were collected in drainage ditches in the streets of "Bair ro Capitalizador", Assumption. The water in the ditches was dark, highly polluted and the bottom was muddy. Aquatic plants were not present. The habitat was not permanent since the water was mainly originated from periodical rains fallen few days before. Snails of the genus Pomacea (Ampulariidae) were seen thriving along with the Biomphalaria.