Capture and Ingestion of Paramecium by Didinium nasutum

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Abstract
SYNOPSIS. This study attempts to analyze how a number of specialized organelles are coordinated in a rapid but complex sequence of events during the capture and ingestion of prey by Didinium. Accidental contact between a Paramecium and the proboscis of a hungry Didinium causes instantaneous discharge of 2 kinds of extrusive organelles from the latter. The short pexicysts attach to the surface of Paramecium but do not penerate. The long toxicysts penetrate the victim, altho their proximal end s remain embedded in the proboscis of Didinium. Cytoplasmic streaming pulls the discharged toxicysts inward, and since they are firmly attached to the prey, the latter is drawn steadily into the cytostome. As the prey is being swallowed, it is compressed, and its volume is reduced by elimination of fluid. When the prey is completely inside the predator, the temporary cytostome closes, and the proboscis is reformed.