Engulfment and Anastomosis in the Cellular Slime Molds (Acrasiales)

Evidence for engulfment and anastomosis of the myxamoebae of several members of the Acrasiales is presented. Photomicrographic evidence for engulfment and anastomosis indicates that these processes are unrelated to any regular sexual mechanism. Vacuolar activity was found to be associated with plasma membrane properties in both anastomosis and engulfment. Frequent multiple engulfment, progressive destruction and digestion of the ingested cells, and ultimate egestion of both intact and partially digested engulfed cells are interpreted as evidence favoring the view that engulfment is a cannibalistic activity. Binucleate and multinucleate amoebae were produced by cell fusion; however, no supporting evidence for nuclear fusion was obtained from observations of either anastomosis or engulfment. It is concluded that no regular sexuality occurs in the usual life cycle of the Acrasiales.