Alternation

(awl-ter-na'-shun). Repeated transition from one state to another. A. of Generations, i. In biology, a generative cycle in which the young do not resemble the parent, but like forms are separated by one or more unlike generations. 2. That form of reproduction in which some of the members of the cycle can produce new beings non-sexually, while in the final stage reproduction is always sexual. Tenia or tapeworm, is an example. The segments, Proglottides, are hermaphrodite, and are evacuated with the feces. From the egg, fertilized after it is shed, is developed the embryo, that is swallowed by another animal, in whose ti ues it forms an encysted stage (Cysticercus, Ccenurus, or Echinococcus). To undergo further development the cysticercus must find another host, where it forms new segments.