On the postcycle parasitism in helminths and its biological significance.

A generalization of the existing data is being done in the work concerning the postcycle parasitism and the postcycle hosts in helminths. So far postcycle parasitism has been observed in various trematodes, cestodes and nematodes parasitizing the digestive tract of vertebrates. The biological significance of the phenomenon comes to the following: survival of mature helminths when they find themselves in the digestive tract of the postcycle hosts; accumulation of such helminths in some cases; and a probable promotion to convert some postcycle hosts into final hosts, too (in historical aspects).