Studies on the germ cell cycle of the digenetic trematode Parorchis acanthus Nicoll

Abstract

1. The anatomy of the male and female genitalia of Parorchis acanthus is described in detail. An extensive receptaculum uterinum occurs in the female system.2. The chromosome number in P. acanthus is twenty-two.3. Spermatogenesis, oogenesis, and fertilization, are described in the adult worm. The chromosome number in both male and female cells is reduced to eleven at the first meiotic division.4. Maturation in the female takes place in the “receptaculum uterinum”.5. Cleavage of the ovum to the three cell stage has been followed.6. The probable synonymy of P. acanthus and P. avitus is discussed.