You would have completely appreciated now that sexual reproduction is definitely the more advanced type of reproduction. It gives for combination of genes from different genetic stocks and imparts the potentiality of better adaptation to the environment and evolution. The involved sex cells (gametes) that are the eggs and sperms come from different individuals that are the female and the male. Species having separate sexes are called dioecious such species are as well called unisexual - composed of individuals of any one sex. But a dissimilar condition pervails in many non-chordates in which both types of organs (testes and ovaries) are found in similar individual. This condition is called bisexualism or more popularly Hermaphroditism and such types of individuals are termed monoecious. The term hermaphrodite comes from Greek mythology where Hermaphroditos the son of Hermes and Aphrodite possessed both female and male sex characters. Hermaphroditism is common in non-chordate groups. In the several incipient forms we can see it even in the ciliate protozoans such as Paramecium. From the account of conjugation of Paramecium, it is clear that it has both a male and a female pronucleus. So each Paramecium serves as a male and a female. In Paramecium during Autogamy, similar micro-nuclear changes as seen during conjugation take place in the single individual. But here like there is no second individual involved, it is comparable to self-fertilisation. Among Metazoa, Hermaphroditism is the rule in flatworms, (Platyhelminthes), pulmonate among gastropods, earthworms and leeches (Annelida) etc. additionally, Hermaphroditism occurs among other animals also, as in some bivalve molluscs.