REDIAL PRODUCTIVITY OF CLINOSTOMUM-COMPLANATUM (TREMATODA, CLINOSTOMATIDAE) WITHIN THE SNAIL HOST

Studies have been conducted on the rediae of Clinostomum complanatum R ud., including the problem of intramolluscan productivity, their popul ation structure and the nature of rediae of different generations. It has been found that the reproduction of rediae is marked by their mass multiplication in the first two generations: this ensures the establi shment of a population of considerable size. The mother redia is the s ole parent redia which produces daughter rediae. The longevity of the mother redia is about 12 days, with a production period of 5 days. Red iae of the second generation which appear on the 7 th-8 th day start t o propagate 3 days later. The peak of production of the second generat ion lasts for 3 days and then shifts to an entirely different phase, t o that of cercarial production. The majority of the third generation a re cercarial producers, with only a few ''mixed'' rediae which are imp ortant in maintaining the redial population. The size of redial popula tion maintains a level of over 1,000-2,500 individuals during a period from 39-59 days. The poly-embryony and the changes in nature in the p roduction of rediae are considered to be attributable to their adaptat ion to the parasitic life of the digenetic trematodes.