REPRODUCTION IN PHORONOPSIS VIRIDIS. THE ANNUAL CYCLE IN THE GONADS, MATURATION AND FERTILIZATION OF THE OVUM

Abstract

The developmental cycle in the gonads of male and female individuals and the inclusions characteristically associated with the reproductive tissue are described. The discovery of spermatozoa in the nephridia of male and female animals and in the coelomic cavity of female animals suggests that spermatozoa are transferred from male to female via the nephridia. Fertilization is found to take place in the body cavity of the female where the nuclei of ripe eggs remain arrested at first metaphase. The diploid ovum contains 13 pairs of chromosomes, and maturation divisions proceed as soon as the egg is shed into the sea. The possibility of protandry is discussed and considered unlikely in this apparently dioecious species.