Asexual and sexual reproduction: This basic distinction seems to have lost any belief∗

Parthenogenesis is a reproductive mechanism derived from sexual reproduction, that biologists during the first decades of our century, considered as distinct from asexual reproduction, namely, the vegetative multiplication. Pseudogamy is genetically similar to parthenogenesis. However, recent authors have adopted a different point of view, considering as asexual the mechanisms involved in parthenogenesis and in pseudogamy. Events evidenced in pseudogamic planarians have shown that the latter phenomenon possesses the basic features of sexuality.