Jehle pointed out that, when immersed in a liquid and intermingled with other molecules, charge fluctuation forces favor the association of identical molecules as nearest neighbors.  In accord with this principle, the multiple copies of a polypeptide encoded by a gene often undergo molecular recognition with each other to form an ordered multi-polypeptide protein structure.  When such a protein is formed from polypeptides produced by two different mutant alleles of a particular gene, the protein composed of a mixture of polypeptides may exhibit greater functional activity than the multi-polypeptide protein formed by each of the mutants alone.  In such a case, the phenomenon is referred to as intragenic complementation.
Intragenic complementation (also called inter-allelic complementation) has been demonstrated in many different genes in a variety of organisms. Crick and Orgel analyzed of the results of such studies and came to the conclusion that intragenic complementation, in general, arises from the interaction of differently defective polypeptide monomers when they form an ordered aggregate they called a “multimer.”