Studies on the reproduction of c1rripedes. VI. Passage of the spermatozoa into the oviducal sac and closure of pores

The changes taking place in the oviducal sac of Pollicipes cornucopia Leach as the oocytes enter are described. Fluid may first be forced through the pores before their closure, but as the sac is distended a granular secretion is forced into them as the inner reticulum becomes disorganized. On the basis of these observations it seems that spermatozoa must enter the sac before it is grossly distended if they are to pass through the pores. Transmission electron micrographs are given showing spermatozoa in the pores and in the lumen of the sac of Balanus balanus (L.). The pore size is adequate for the spermatozoa only after the accessory droplet has been lost. Many spermatozoa within the lumen appear to have disintegrated, the membranes having been lost and the axonemes separated. Some calculations of the time required for penetration and the number of spermatozoa able to enter the sac, assuming one passes through each pore, are given. The origin of the various secretions is discussed and their possible relation to the motility of the spermatozoa considered. The advantages of pseudo-copulation are stressed.