Abstract
The course of infection of Raillietina cesticllus in the chicken has been studied and information is presented on proglottid output, the dynamics of infection and the distribution and growth of the cestode. A posterior migration of young cestodes during the first 7 days of infection was confirmed and a progressive destrobilization of the worms was observed with complete destrobilization occurring 70 days after infection. No regeneration of strobilae occurs and the scolices are eventually eliminated. A marked difference in the rate of destrobilization in the two host sexes was noted.