[The redial generations of Fasciola hepatica L. in Lymnaea truncatula Müller. Multiplicity of developmental patterns].

The different rediae of Fasciola hepatica were counted in 398 snails individually exposed to single miracidium and then killed at day 30 post-exposure at 20 degrees C. When the redia n degree 1 of generation 1 was alive (327 snails), it produced rediae of generation 2 with high numbers (until 19): these rediae were precocious and could be followed by differentiation of cercariae. When the redia n degree 1 of generation 1 was degenerated (71 snails), an other redia--redia n degree 2 of generation 1 or redia n degree 1 of generation 2--produced daughter rediae with low numbers (until 9): these latter rediae differentiated in the same time as cercariae. The significance of these observations is discussed.