• (n.) The substance from which attraction spheres develop in mitotic cell division, and of which they consist.
Ar'cho·plasm noun [ See Archon ; Plasma .] (Biol.) The substance from which attraction spheres develop in mitotic cell division, and of which they consist. 
Archoplasm or archiplasm is the protoplasmic material surrounding the centrosome, formerly thought to be involved in the formation of the asters and spindle during mitosis.