In the light of the above discussion, it appears that the parasites and their hosts form a biotype which is both exclusive and interchangeable. In the former case it is of such an extreme association as to be confined to a very limited geographical region. Using the parasites as “biological tags” in such cases appears to have great possibilities. In specific diagnosis and in creation of new species information could be gleaned from the study of other characteristics such as ovic embryos. Biochemical and histochemical investigations such as the formation of ovic embryos offer interesting new avenues of research.