It has been shown that C′x and C′y correspond to C′1,4 and C′2,3, respectively. The complex EAC′1,4 reacts with C′2 forming a complex EAC′1,4,2, which in turn reacts with C′3, yielding an activated or damaged cell, E*, which then undergoes the terminal transformation reaction to a ghost with release of hemoglobin. Mg++ is involved in the action of C′2. The complex EAC′1,4,2 has been isolated, and its reaction with C′2 has been studied. In a system containing optimal Ca++ and Mg++ the reaction between EAC′1,4,2 and C′3 is the rate-controlling process. In a Mg++ deficient system the C′2 step is the pacemaker. The complex EAC′1,4,2 can serve as a substrate for the determination of C′3.