BEHAVIOR OF THE NURSE-CELLS OF LITTORINA IRRORATA (SAY)

¹ From the U. S. Fisheries Biological Laboratory, Beaufort, North Carolina, and the Department of Biology, Vanderbilt University, Nashville

The nurse-cells of L. irrorata with tufts of sperm attached are moulded in the male into rudimentary spermatophores and are then passed to the female. In the uterus the sperm become detached from the nurse-cells and migrate to the seminal receptacle where they are stored. The nurse-cells then ingest any remaining spermatozoa, break them down, and are themselves eventually extruded. Nurse-cells with tufts of sperm in the sperm duct show an aggregation reaction which leads to the formation of three-dimensional pinwheels. The tufts of sperm are attached by their tails to each other, and the nurse-cells lie radially disposed. These aggregates disperse first by detachment of the nurse-cells, leaving the sperm attached by their tails, then by disentanglement of each of the sperm. The free sperm then show a thigmotaxis. Sperm not attached to nurse-cells (from seminal receptacle or from a copulate in which segregation has already occurred) show the usual ead-to-head agglutination reaction. The behavior of the nurse-cells and spermatozoa is viewed as a mechanism whereby the latter are segregated from the former. This behavior is compared with the clumping of the apyrene and eupyrene spermatozoa of Goniobasis.