Occurrence of a sporocyst generation of Fasciola gigantica in the mollusc Lymnaea rubiginosa.

Thirty laboratory-reared, juvenile Lymnae rubiginosa were exposed to 20 miracidia each of Fasciola gigantica. Eight days postinfection snails were dissected, and clearly recognizable sporocysts were recovered from the mantle collar and renal vein. Behavior of sporocysts and mother rediae differed markedly. These observations contradict those of direct metamorphosis of miracidium into redia as reported by Ogambo-Ongoma and Goodman (1976).