[Fasciola hepatica L.: the productivity of a sporocyst as a function of the size of Lymnaea truncatula Müller].

Experimental studies were undertaken on the rediae of Fasciola hepatica and on their content in two populations of Lymnaea truncatula snails, individually exposed to a single miracidium and fixed for histologic observations just after their death between days 74 and 81 postexposure at 20 degrees C. The numbers of free rediae and of larval stages per snail increased with the shell height. A constant number of free rediae was observed in snails measuring 11 mm and more in size. There was no limit of increase in number for the different types of larval stages, but these increases were lower for the youngest larval types. The number of larval stages per redia also increased with snail size; it was always higher in the first redial generation than in the following generations. Cercariae were produced by 40%-43% of the rediae contained in a snail: 65%-80% of these mature rediae belonged to the first generation and to the first cohort of the second generation.