Kline, George L.  “Form, Concrescence, and Concretum:  A Neo-Whiteheadian           Analysis.”  (Unpubl, 1967.)

Abstract

Whitehead distinguishes too sharply between concrescence and transition and not sharply enough between concrescence and concretum (post actual occasion).  Transition is the relation of concrescence to concretum (which provide the data which are causally objectified by physical prehensions).