Ford, Lewis S.  "Panpsychism and the Early History of Prehension."  Process Studies 24 (1995): 15-33.

Abstract

Throughout the early part of "Science and the Modern World", only some  events enjoy subjectivity.  Prehension as first introduced can be understood strictly in terms of events related by a common eternal object.  From the standpoint of one of these events, prehension can be understood in terms of perception only if we substitute a perceiving subject for the event.  The revision caused by the epochal theory of time restricts active occasions to the present, yet even so physical occasions may be devoid of subjectivity.  Some may find panpsychism in three paragraphs which may be a very late insertion in the chapter on "Abstraction."  That value is the intrinsic reality of an event does not entail panpsychism, but merely contrasts with the extrinsic reality evident in scientific materialism.  The notion that every actual occasion has a mental occasion is first articulated in the 1926 essay on "Time," but full panpsychism, that every prehension has a subject, first appears in "Process and Reality, Part III".  Prehension in "Science and the Modern World" is an extremely thin and abstract notion which Whitehead was able to develop into the rich notion of "Process and Reality".  [Abstract from The Philosopher's Index]