1911 Encyclopædia Britannica (1911)
“ The transition of the larva from the intermediate to the final host is accomplished by the habits of carnivorous animals. The Elasmobranchs swallow infected molluscs or fish; pike and trout devour smaller fry; birds pick up sticklebacks, insects and worms which contain Cestode larvae; and man lays himself open to infection by eating the uncooked or partially prepared flesh of many animals. The peculiar feature of the larval history of Cestodes is the development in most cases of a cyst or hydatid on the inner wall of which the scolex is formed by invagination. ”
