COMPARATIVE-STUDIES ON THE PRODUCTIVITY OF FASCIOLA-GIGANTICA AND F-HEPATICA SPOROCYSTS IN LYMNAEA-TOMENTOSA THAT DIED AFTER A CERCARIAL SHEDDING OR WITHOUT EMISSION

A histology study was performed on Fasciola gigantica- or F. hepatica- infected Lymnaea tomentosa that died after a cercarial shedding or wit hout emission to compare the parasite productivity of each trematode. Degenerated rediae increased in number throughout the experiment. Thei r number rose rapidly after day 79 in snails that died after shedding in the F. gigantica group; they increased more slowly in snails that d ied without shedding. In the F. hepatica group the number rose after d ay 63 in the former snails and after day 79 in the latter. The content s of normal rediae evolved inversely. The number of morulae, for examp le, dropped rapidly after day 79 in the F. gigantica group. In the F. hepatica group it dropped after day 63 in snails that died after shedd ing and decreased after day 79 in the other dead snails. Free and dege nerated cercariae were more numerous in snails that died without emiss ion than in those that died at shedding. They rapidly increased in num ber after day 77. The numbers of rediae of F. gigantica were substanti ally greater than those of F. hepatica. In each group considered separ ately, it was likewise higher in snails that died without shedding tha n in those that died after the shedding of cercariae.