Although the chance of successful recombination between any mating pair of rII mutants is small, a single petri dish could be the basis for millions of trials at once.
[2] Benzer's concept was quite controversial within classical genetic thought, in which each gene is treated as a singular point along a chromosome, not a divisible stretch of nucleic acids (as implied by the work of Watson and Crick).
In his early work, he identified two separate but very close loci within the rII region, which he suggested were nucleotide sequences that encoded different polypeptides; he called these "cistrons".
For example, Francis Crick and others used one of the peculiar r mutants Benzer had found (a deletion that fused the A and B cistrons of rII) to demonstrate the triplet nature of the genetic code.
[8] The principal that three sequential bases of DNA code for each amino acid was demonstrated in 1961 using frameshift mutations in the rIIB gene of bacteriophage T4[9][10] (also see Crick, Brenner et al. experiment).