Lee, Harold N.  “Causal Efficacy and Continuity in Whitehead's Philosophy.”  Tulane Studies in Philosophy 10 (1961): 59-70.

Abstract

Whitehead's doctrine of the perception of causal efficacy holds together two aspects of his philosophy: realism and empiricism.  But his insistence on the atomicity of actual entities compromises the continuity necessary to the perception of causal efficacy.  He says that both continuity and atomicity must be taken into consideration, but he fails to show the relation between them.  If he had taken the historic route of actual entities as his unit and had let actual occasions be analytic derivatives from an historic route, he would have avoided the difficulties that arise in his treatment of continuity.  [Abstract from The Philosopher’s Index]